LSU AgCenter's Weekly Message

LSU AgCenter’s Website Offers Time-Tested and New Resources To Gardeners

During this time of year when working outside in the garden isn’t as pleasurable, you might consider using the time to do some garden-related reading. The LSU AgCenter has a lot of resources that address a variety of topics, and there are certain ones that we give out repeatedly.

Below is information on some resources that you might take time to read as you sit in the cool of your house or on your porch. Most of these publications are available on our website, www.lsuagcenter.com. If you don’t have internet access, you can call the LSU AgCenter’s Washington Parish office (985-839-7855) and ask that a copy be sent to you.

The Louisiana Vegetable Planting Guide contains much of the information you need to plant a home vegetable garden, including recommended cultivars of specific vegetables, when to plant, and how much and when to fertilize. Additional information about growing specific vegetables is available by going to the “Lawn & Garden” section on our website and then choosing “Fruits, Nuts and Vegetables,” followed by “Vegetables” and then “Individual Crops.” If you would like to plant your garden in a raised bed, also look for the Raised Beds publication, which is part of the Home Garden Series.

The Louisiana Home Orchard publication has basic information on growing a wide variety of fruit crops, ranging from blueberries and muscadines to mayhaws and peaches. Like the vegetable gardening publication, it includes cultivar and fertilizer recommendations, as well as planting information. It also has information on training/pruning and some common disease and insect issues.

While the Louisiana Home Orchard publication covers a wide range of fruit crops, there are resources that provide more in-depth information about several popular fruit crops. These include Louisiana Home Citrus Production, Blackberry Growing Guide, Louisiana Home Muscadine Production, and Figs for Commercial and Home Production in Louisiana. For blueberries, Mississippi State University Extension’s website offers Establishment and Maintenance of Blueberries.

For information about growing herbs, check out Herb Gardening in Louisiana, A Guide to Growing a School Herb Garden, or the Culinary Herbs publication in the Sustainable Gardening for School and Home Gardens series.

The vegetable, fruit, and herb resources mentioned above are available online or from our local offices, at no charge to you. The LSU AgCenter also offers Louisiana Home Fruit and Nut Production (79 pages) and Louisiana Home Vegetable Gardening (121 pages) books for $20 each. To order one of these, go to https://store.lsuagcenter.com/ or call 225-578-2263.

In the landscape arena, publications include Trees for Louisiana Landscapes and Shrubs for Louisiana Landscapes. Information on Louisiana Super Plants can be found on the respective section of our website.

Within the past few years, LSU AgCenter Hammond Research Station’s Drs. Damon Abdi and Jeb Fields, with others, have produced several fact sheets in the Landscape Ornamentals Series, including the following: Best Practices for Landscape Bed Preparation, Best Practices for Pruning Ornamental Trees in the Landscape, Proper Balled-and-Burlapped (B&B) Tree and Shrub Care, Managing Girdled Roots in the Landscape, Using Drought Stress Indicator Plants in the Landscape, Insect Insights for the Home Garden, Hand Pruner Selection in the Landscape, Sanitizing Tools to Prevent Disease, Mower Maintenance -

Cleaning Lawn Residues Off of Mower Decks, Landscape Edging Concepts, Installing and Maintaining a French Drain, Principles of Permeable Paving, Seat Walls in the Landscape, and Designing and Building a Pergola.

Hammond Research Station faculty, staff, and graduate students have also created a series of Louisiana Landscape Guide fact sheets, including Evergreen Shrub, Sun-Loving Bedding Plants for the Warm Season, Shade-Loving Plants for the Warm Season, Colorful Cool-Season Plants for Sunny Areas, Colorful Cool-Season Plants for Shady Areas.

For those who would like to have a garden that is both attractive and supports pollinating insects, we have Pollinator Gardening in Louisiana (part of the Urban Pollinator Conservation Series), Use of Flowering Plants (in the Protecting Pollinators in Urban Areas series), and Butterfly Gardening for Louisianians.

Those interested in cut flowers may find the newly released Growers Guide for Cut Flowers for Louisiana and the Gulf Coast helpful.

There are a number of helpful resources on lawn care in the Louisiana Home Lawns Series. To get to these resources, go to our website and choose “Lawn & Garden” and then “Turfgrass.” The Louisiana Lawns Best Management Practices publication also has useful information. I like the tables on p. 5 that summarize fertility and mowing height recommendations for common turfgrasses.

Of course, you can read articles I’ve written on my page within the LSU AgCenter website.

If you like watching videos, the LSU AgCenter has a YouTube channel with videos about a variety of topics, including gardening. Additionally, my colleagues in the Greater New Orleans area have put together several video series – available on the LSU AgCenter website – including the vegetable-focused Home Gardening Class and a Home Composting Certificate Course.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

LSU AgCenter Taking Orders for Sweet Potato "Seed"

Sweet potatoes are well-adapted to our hot, humid summers. Besides the nutritious roots that we normally eat, young leaves of sweet potato can be consumed as well. They can be sauteed, boiled, or even eaten raw.

Growing sweet potatoes is different from growing white (“Irish”) potatoes or vegetables that are grown from true seed. The production cycle begins when sweet potatoes (“seed”) from the previous harvest season are planted in the spring, to produce slips for transplanting.

Gardeners who just want to plant a few hills of sweet potatoes can often find slips for sale at local garden centers. They can be planted between late April and the end of June in southern Louisiana.

Those who plan to plant a large area of sweet potatoes or want a specific variety may prefer to grow their own slips. Sweet potatoes can be bedded for slip production beginning around mid-March in southern Louisiana. Allow six to eight weeks for slips to grow.

It’s important that the roots used for slip production are free of disease and of good quality. The LSU AgCenter’s Sweet Potato Research Station offers seed potatoes grown from virus-tested planting material through its foundation seed program.

The variety Beauregard is available for $25 per 40-pound box. Avoyelles, Bayou Belle, Evangeline, and Orleans roots can be purchased in a 40-pound box for $30 or a 20-pound box for $16. Murasaki-29 and Sakura are available at $16 per 20-pound box.

The Sweet Potato Research Station will sell slips of these and other varieties – including Bonita, Burgundy, Heart-o-Gold, O’Henry, Okinawan, Porto Rico, and Vermilion – in the spring. The price is expected to be $0.45 per slip with a minimum order of 100 slips ($45). This is more than you would pay for slips from local retailers, but it does offer people the chance to purchase slips of varieties that they might not otherwise be able to find.

Beauregard is a classic Louisiana sweet potato variety that was released by the Louisiana Agricultural Experiment Station in 1987. Orleans is similar to Beauregard but produces more uniform roots. This is important for commercial growers who are trying to maximize production of U.S. No. 1 grade sweet potatoes but probably not that important in a home garden.

Evangeline produces roots that have a high sucrose content and taste especially sweet. While microwaving typically does not result in sweet potatoes that are as sweet as those baked in an oven, because of its high sucrose content, Evangeline sweet potatoes can be microwaved and still taste sweet. From a production standpoint, Evangeline has the advantage of being resistant to southern root knot nematodes.

Avoyelles is the LSU AgCenter sweet potato breeding program’s newest release. It can be harvested earlier than other varieties, with roots maturing in approximately 90 days instead of the 110 to 120 days after slip planting that most varieties need. Like Evangeline, it’s resistant to southern root knot nematodes.

Information about most other varieties can be found on the LSU AgCenter Sweet Potato Research Station’s website.

The Sweet Potato Research Station has begun taking seed orders via an online form (https://lsu.qualtrics.com/jfe/form/SV_8uDlYbJftXBBjzE). Orders submitted online are due by Monday, February 3, 2025. If you’re in Tangipahoa or Washington Parish and do not have internet access, please contact me by Thursday, January 30, 2025, to place your order.

If you want to order slips, contact the Sweet Potato Research Station directly (318-435-2155), beginning in early March.

Under sweetpotato weevil quarantine regulations, growers in Louisiana who raise sweet potatoes to sell are required to have a Sweet Potato Dealer’s Permit from the Louisiana Department of Agriculture and Forestry. Home gardeners are not required to have a permit but are encouraged to take measures to reduce weevil populations.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

LSU AgCenter Taking Orders for Sweet Potato "Seed"

Sweet potatoes are well-adapted to our hot, humid summers. Besides the nutritious roots that we normally eat, young leaves of sweet potato can be consumed as well. They can be sautéed, boiled, or even eaten raw.

Growing sweet potatoes is different from growing white (“Irish”) potatoes or vegetables that are grown from true seed. The production cycle begins when sweet potatoes (“seed”) from the previous harvest season are planted in the spring, to produce slips for transplanting.

Gardeners who just want to plant a few hills of sweet potatoes can often find slips for sale at local garden centers. These can be planted between late April and the end of June in southern Louisiana.

Those who plan to plant a large area of sweet potatoes or want a specific variety may prefer to grow their own slips. Sweet potatoes can be bedded for slip production beginning around mid-March in southern Louisiana. Allow six to eight weeks for slips to grow.

It’s important that the roots used for slip production are free of disease and of good quality. The LSU AgCenter’s Sweet Potato Research Station offers seed potatoes grown from virus-tested planting material through its foundation seed program.

The variety Beauregard is available for $25 per 40-pound box or $16 per 20-pound box. Avoyelles, Bayou Belle, Evangeline, and Orleans roots can be purchased in a 40-pound box for $30 or a 20-pound box for $16. Bonita, Bellevue, Murasaki-29, O’Henry, and Sakura are available at $16 per 20-pound box.

The Sweet Potato Research Station will sell slips of most of the above-mentioned varieties as well as several others – Burgundy, Heart-o-Gold, Okinawan, Porto Rico, and Vermilion – in the spring. The price is expected to be $0.45 per slip with a minimum order of 100 slips ($45). This is more than you would likely pay for slips from local retailers, but it gives people a chance to purchase slips of varieties that they might not otherwise be able to find.

Beauregard is a classic Louisiana sweet potato variety that was released by the Louisiana Agricultural Experiment Station in 1987. Orleans is similar to Beauregard but produces more uniform roots. This is important for commercial growers who are trying to maximize production of U.S. No. 1 grade sweet potatoes but probably not that important in a home garden.

Evangeline produces roots that have a high sucrose content and taste especially sweet. While microwaving typically does not result in sweet potatoes that are as sweet as those baked in an oven, because of its high sucrose content, Evangeline sweet potatoes can be microwaved and still taste sweet. From a production standpoint, Evangeline has the advantage of being resistant to southern root knot nematodes.

Avoyelles is the LSU AgCenter sweet potato breeding program’s newest release. It can be harvested earlier than other varieties, with roots maturing in approximately 90 days instead of the 110 to 120 days after slip planting that most varieties need. Like Evangeline, it’s resistant to southern root knot nematodes.

Information about most other varieties can be found on the LSU AgCenter Sweet Potato Research Station’s website.

The Sweet Potato Research Station takes seed orders via an online form (https://lsu.qualtrics.com/jfe/form/SV_es6CkGZzftx4NKe). Orders placed online are due by Friday, January 16, 2026. If you’re in Tangipahoa or Washington Parish and do not have internet access, please contact me by Monday, January 12, 2026, to place your order.

If you want to order slips, contact the Sweet Potato Research Station directly (318-435-2155), beginning in late March.

Under sweet potato weevil quarantine regulations, growers in Louisiana who raise sweet potatoes to sell are required to have a Sweet Potato Dealer’s Permit from the Louisiana Department of Agriculture and Forestry. Home gardeners are not required to have a permit but are encouraged to take measures to reduce weevil populations.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Sweet Potato "Seed" Available from LSU AgCenter

The sweet potato is well-adapted to our hot, humid summers. Besides the roots that we normally eat, young leaves of sweet potato can be consumed as well. They can be sauteed, boiled, or even eaten raw.

Growing sweet potatoes is different from growing white (“Irish”) potatoes or vegetables that are grown from true seed. The production cycle begins when sweet potatoes (“seed”) from the previous harvest season are planted in the spring, to produce slips for transplanting.

Gardeners who just want to plant a few hills of sweet potatoes can often find slips for sale at local garden centers. They can be planted between late April and the end of June in southern Louisiana.

Those who plan to plant a large area of sweet potatoes or want a specific variety may prefer to grow their own slips. Sweet potatoes can be bedded for slip production beginning around mid-March in southern Louisiana. Allow six to eight weeks for slips to grow.

It’s important that the roots used for slip production be free of disease and of good quality. The LSU AgCenter’s Sweet Potato Research Station offers seed potatoes grown from virus-tested planting material through its foundation seed program.

The variety Beauregard is available for $25 per 40-pound box. Bayou Belle, Bonita, Burgundy, Murasaki, Orleans, Porto Rico, and Sakura are available at $16 per 20-pound box. Quantities of Evangeline are limited this year, so roots are not offered at this time, but the Sweet Potato Research Station will sell Evangeline slips in the spring.

Beauregard is a classic Louisiana sweet potato variety that was released by the Louisiana Agricultural Experiment Station in 1987. Orleans is similar to Beauregard but produces more uniform roots. This is important for commercial growers who are trying to maximize production of U.S. No. 1 grade sweet potatoes but probably not that important in a home garden.

Evangeline produces roots that have a high sucrose content and taste especially sweet. While microwaving typically does not result in sweet potatoes that are as sweet as those baked in an oven, because of its high sucrose content, Evangeline sweet potatoes can be microwaved and still taste sweet. From a production standpoint, Evangeline has the advantage of being resistant to root knot nematodes.

Information about other varieties can be found on the LSU AgCenter Sweet Potato Research Station’s website.

The Sweet Potato Research Station has begun taking seed orders via an online form (https://lsu.qualtrics.com/jfe/form/SV_b8xaiTEQ6rdw610). Orders submitted online are due by Friday, January 12, 2024. If you’re in Tangipahoa or Washington Parish and do not have internet access, please contact me by Monday, January 8, 2024, to place your order.

Under sweetpotato weevil quarantine regulations, growers in Louisiana who raise sweet potatoes to sell are required to have a Sweet Potato Dealer’s Permit from the Louisiana Department of Agriculture and Forestry. Home gardeners are not required to have a permit but are encouraged to take measures to reduce weevil populations.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Some Licenses and Certifications Related to Landscape Horticulture Work

I occasionally get questions from people who are interested in getting into landscape-related work for pay. The easiest type to get into is general yard work, including mowing, edging, and hand-weeding. Without a state license, as long as the work is not on commercial property, one can also engage in “trimming of hedges and shrubbery, under the direction and responsibility of the owner of the property” and pruning trees “under the specific direction and responsibility of the owner of the property” if “the branch to be removed is two inches or less in diameter and is within ten feet of ground level.”

If a person is paid a fee for doing landscape work beyond what is described above, Louisiana generally requires a license. A Landscape Horticulturist license allows a person to do things such as preparing beds, installing landscape plants or sod, giving advice on plant selection and placement, fertilizing, and doing shrub pruning beyond what is described in the above paragraph. Licensing requires passing an exam administered by the Louisiana Department of Agriculture and Forestry (LDAF) and paying a fee. The study guide for the exam is called The Louisiana Manual for the Environmental Horticulture Industry and can be ordered from the Louisiana Nursery and Landscape Association.

It’s not required by law, but some people who do landscaping work also choose to get Certified Nursery and Landscape Professional (CNLP) certification through the Louisiana Nursery and Landscape Association (LNLA). The study guide for this is the same one for the state license exam. LNLA hosts CNLP manual review and exam sessions.

One thing that a Landscape Horticulturist license does not allow people to do is to be paid for a landscape plan itself. While a Landscape Horticulturist can draw plans while preparing to install plants, they cannot sell a landscape design itself. In Louisiana, to do this, one must be licensed as a Landscape Architect. (Describing what’s required to become a landscape architect is beyond the scope of this article.)

Another profession for which state licensure is required is arborists. These are people who, as well as removing trees, care for them by doing things such as pruning, fertilizing, and cabling. As with the Landscape Horticulturist license, to attain the Arborist license, one must pass an exam and pay a fee. The study guide for this exam is the Arborists' Certification Study Guide from the International Society of Arboriculture (ISA). There is a separate certification, Utility Arborist, for those who remove trees or prune “along utility rights of way.”

There are also options to get tree work credentials beyond the required state license. For example, some people choose to become Certified Arborists through ISA.

People who do landscape work sometimes want to be able to, for example, apply herbicides for lawn weeds or use fungicides or insecticides on landscape plants. State law requires those who apply herbicides, insecticides, fungicides, or other pesticides to others’ landscapes for a fee to have a pesticide applicator’s license and commercial applicator certification. (For Arborists, there is an exception that allows application of “…pesticides only for the purposes of retarding decay or disease.”) Those who will be applying pesticides to landscape plants and turfgrass take a general standards exam and the ornamental and turf pest control exam. The study materials for these are the National Pesticide Applicator Certification Core Manual and the Ornamental and Turf Pest Management study guide, respectively. Both can be ordered from LSU AgCenter’s Online Store.

For more information about Landscape Horticulturist, Arborist, and related licenses and permits, you can check out LDAF’s Nursery and Landscape Licensing website (https://www.ldaf.la.gov/plants/nurseries-landscaping). People interested in hiring someone can also use this website to find names of licensed individuals. For information on pesticide licenses, see LDAF’s Pesticide Licensing website (https://www.ldaf.la.gov/plants/pesticides/pesticide-licensing).

There will likely be other requirements for operating a landscape-related business, such as a business license from the local government entity in which it’s based. Organizations such as the Louisiana Small Business Development Center or your local chamber of commerce can likely provide guidance.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

It’s Time to Prune Some Types of Roses, Demonstration to be Held

Late January to mid-February is the primary time of year to prune everblooming roses in Louisiana. Examples of these include hybrid tea, grandiflora, floribunda, shrub (including those in the Knock Out series), and miniature roses. On the other hand, wait until shortly after once-blooming roses flower to prune them. Examples of once-bloomers include Lady Banks and Cherokee roses.

A first step in pruning any type of rose is to remove damaged, dead, or diseased shoots.

Hybrid tea and grandiflora roses tend to have more upright growth habits than other roses and need more severe pruning. When pruning these, remove less vigorous canes – generally ones smaller than the diameter of a pencil – at the point of origin. Leave about six to eight healthy canes that have a diameter at least as big as that of an adult finger. Cut these canes back to approximately 2 feet in height. Make cuts about 0.25 inch above an outward facing bud so that the shoot that emerges will grow away from the center of the plant.

Personal preference can largely dictate how other everblooming roses are pruned. As you decide if and how to prune them, keep in mind some general principles: Multiple shoots will likely emerge from below a cut made in the middle of a stem. If you want to open up the canopy, you can remove branches at their points of origin. If one of these other types of everblooming roses is overgrown, consider cutting it back by one-quarter to one-half of its original height.

Everblooming roses can be pruned a second time in late August or early September, with less growth being removed at this time than in January or February. Two-and-one-half to 3 feet of stems can be cut from hybrid tea and grandiflora roses. As in late winter, other everblooming roses are generally pruned less severely.

Some climbing roses are everbloomers while others are once-bloomers, so the best time for pruning these varies. When you do prune climbing roses, do so as needed to train them to the structure on which you want them to grow.

When pruning, use clean, sharp pruning shears (for smaller cuts) or loppers (for stems larger than one-half inch in diameter) to avoid wounding stems more than necessary. Bypass shears or loppers (ones with blades on both sides) are generally preferable, since anvil types may crush branches to some extent.

In cooperation with the Washington Parish Library System, the LSU AgCenter will offer a rose pruning demonstration at the Franklinton Branch Library (825 Free St.) at 1:00 PM on Wednesday, January 7, 2024. If you plan to come and would like to be notified of cancellation due to inclement weather or illness, please call 985-277-1850 or send an e-mail to mhferguson@agcenter.lsu.edu, to pre-register. For accommodations for persons with disabilities, please contact us as soon as possible. The LSU AgCenter and LSU provide equal opportunities in programs and employment.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Working with Wet Areas on Your Land

Last week’s rains – about 5 inches in two days at my house – provided a good chance to observe where water accumulates in our yards, on our fields, and in our woods.

There are ways to improve drainage in some places. Sometimes it may be as simple as cleaning out a ditch so that water has a place to go. Grading and French drains are options in some situations.

In a lot of cases, though, it’s more practical to just work with the conditions you have. This goes along with the “right plant, right place” principle, or matching the plant to the site.

While some plants cannot tolerate even short periods of standing water or saturated soil, there are quite a few plants suited to wet areas.

Some herbaceous (non-woody) plants for wet areas include carpetgrass (Axonopus fissifolius), Virginia blue flag iris (Iris virginica), Louisiana irises (giant blue iris [I. giganticaerulea], zigzag iris [I. brevicaulis], dixie iris [I. hexagona], copper iris [I. fulva], Abbeville iris [Iris x nelsonii], and hybrids of these), southern swamp lily (Crinum americanum), swamp spider lily (Hymenocallis liriosme), Texas star hibiscus or scarlet rose-mallow (Hibiscus coccineus), crimsoneyed rosemallow or swamp rose-mallow (Hibiscus moscheutos), common or soft rush (Juncus effusus), and needlegrass rush or black needlerush (J. roemerianus).

Some trees and shrubs for wet areas include bald cypress (Taxodium distichum), pond cypress (T. ascendens or T. distichum var. imbricarium), nuttall oak (Quercus texana, formerly Q. nuttallii), water oak (Q. nigra), black gum or tupelo (Nyssa sylvatica), swamp tupelo (N. biflora), water tupelo (N. aquatica), Drummond or swamp red maple (Acer rubrum var. drummondii), river birch (Betula nigra), parsley hawthorn (Crataegus marshallii), mayhaws (Crataegus opaca and other Crataegus species), common persimmon (Diospyros virginiana), sweet bay magnolia (Magnolia virginiana), wax myrtle (Myrica cerifera or Morella cerifera), titi (Cyrilla racemiflora), Florida anise (Illicium floridanum), American holly (Ilex opaca), dahoon holly (I. cassine), possumhaw (I. decidua), winterberry holly (I. verticillata), buttonbush (Cephalanthus occidentalis), and Virginia willow or sweetspire (Itea virginica).

The plants I mention here are just some examples. One way to get an idea of whether a plant is suited to wet areas is to check a resource such as the US Department of Agriculture Plants database (https://plants.usda.gov/), the US Geological Survey Plants of Louisiana website (https://warcapps.usgs.gov/PlantID/), or the LSU’s Louisiana Plant Identification and Interactive Ecosystem Virtual Tours site (http://www.rnr.lsu.edu/plantid/) and look at the wetland status of the plant. Plants rated as OBL, or obligate wetland plants, are almost always found in wetlands. Those rated as FACW, or facultative wetland plants, are usually found in wetlands, and those rated as FAC, or facultative plants, are found in both wetlands and non-wetlands. Those least likely to be suited to wet areas are the UPL, or upland, plants which are rarely found in wetlands.

Be sure to also take other factors, like the expected mature size of the plant and how much sun or shade it needs, when making plant choices.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Use Good Techniques When Planting Trees and Shrubs

Fall is one of the best times to plant most types of trees and shrubs. With enough coddling, containerized plants can be installed at any time of year, but planting after temperatures cool in the fall gives them a good deal of time to establish their root systems before the hottest weather and greatest water demand occur the following year.

There are exceptions to the planting-containerized-trees-and-shrubs-in-the-fall-is-best rule. Citrus trees and fig trees, which are more cold-sensitive when young, can be planted in late winter or early spring.

Like most types of containerized trees and shrubs, those sold in the balled-and-burlapped (B&B) form can be planted in the fall. Bare-root plants should be planted while they’re dormant.

When choosing a plant for a location or, vice versa, a location for a plant, make sure to match the plant to the site. Account for the amount of sun/shade the site gets, how wet or dry it is, how much space there is between it and a building or fence, if there’s a powerline overhead, and your USDA Plant Hardiness Zone (9A in most of Tangipahoa and Washington Parishes, with some patches of 8B).

Dig the planting hole at least twice as wide as the root ball but no deeper than its height. (For B&B plants, make the hole a little shallower than the height of the root ball.) We don’t want the root ball to sink as soil settles. If you accidentally dig the hole deeper than it needs to be, firm the soil in the bottom of the hole so that it won’t settle very much after the plant has been put in place.

If you’re planting a tree, the trunk flare should remain aboveground. Don’t bury the base of the trunk, as this can result in problems down the road.

Put the native soil that you’ve removed back into the planting hole rather than replacing it with soil conditioner, compost, etc. If you use some amount of such an amendment, mix it well with the native soil. For a plant to grow well in the long run, it will need to be able to grow roots in the native soil beyond the planting hole. Break up any clods in the soil that’s being put back in the hole.

If you’re planting containerized plants, watch for roots that have hit the edge of the container and started growing downward or begun to circle the root ball. Do not allow roots to continue growing in this manner. You can use pruning shears or another tool to shave off the outer edge of the sides of the root ball. (Doing this to the bottom of the root ball isn’t necessary. It’s most important that roots are able to grow horizontally near the surface of the soil.) On large, containerized root balls, removing a 1-inch-thick layer is usually appropriate.

Remove any stake (bamboo, metal, etc.) that came with the plant so that it won’t wound the plant as it grows. Most plants will not need to be staked, but if a plant is unable to stand on its own under windy conditions, an appropriate post-planting staking system can be used.

Two to four inches of mulch, such as pine straw or bark, is helpful for discouraging weed growth near plants. However, don’t place mulch so close to the plant that it comes in contact with the trunk. Avoid “volcano mulching.”

Water plants adequately while they’re getting established.

The fourth class in the gardening and lawn care series will take place next Tuesday, September 30, at 6 PM at the Lee Memorial Forest Main Lodge (21139 Lee Memorial Drive, Franklinton). Please join us if you’re interested! Call or email me to register or for more information. The LSU AgCenter and LSU provide equal opportunities in programs and employment.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

You Don’t Have to Wait for Cold Weather to Plant Some Cool-Season Vegetables

It may not feel like it right now, but we’re approaching a time of year when we can plant many of our cool-season vegetables. Some can be planted earlier and some later, but almost all can be planted between mid-September and mid-October. These include cabbage, kohlrabi, broccoli, cauliflower, Brussels sprouts, bok choy, greens (collard, kale, mustard, turnip), radishes, beets, carrots, lettuce, shallots, garlic, and green (“English”), sugar snap, and snow peas.

There are a few exceptions. Seed pieces of white (“Irish”) potatoes can be planted between August and mid-September and again in late winter, and transplants of bulb-forming onions that grow well in Louisiana should be set out between mid-December and January. Fava beans aren’t a very common crop here, but I understand that the time for sowing these is October through November.

A second sweet spot during which a lot of cool-season veggies can be planted is late January through February. Cabbage, kohlrabi, broccoli, cauliflower, greens, radishes, beets, carrots, lettuce, shallots, and white potatoes can be planted at this time. Many can be established earlier or later, too.

If you want to give the garden a rest, you might consider seeding a fall cover crop. Cover crops can be used to build up soil organic matter, take nitrogen from the air and put it in the soil (in the case of plants in the bean family, or legumes), prevent loss of nutrients from the soil during the off-season (after adding compost or manure, for example), suppress weed growth, and prevent erosion. The first half of October is a time when many cool-season cover crop species – such as cereal rye, annual ryegrass, wheat, oats, hairy vetch, and crimson clover – can be planted.

The second class in the gardening and lawn care series will take place next Tuesday, September 16, at 6 PM at the Lee Memorial Forest Main Lodge (21139 Lee Memorial Drive, Franklinton). Please join us if you’re interested! Call or email me to register or for more information. The LSU AgCenter and LSU provide equal opportunities in programs and employment.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

LSU AgCenter Provides Opportunities to Learn about Composting

Composting is a way to take yard, garden, and kitchen “waste” and turn it into something useful.

It doesn’t have to be all that complicated. You don’t need any one type of structure to do it. In fact, you don’t have to use structure at all - one of our composting fact sheets addresses composting with a “compost mound.” If you want to do vermicomposting (composting with worms), you can even do it indoors. Composting depends in part on microscopic organisms (bacteria and fungi) to break down organic materials into organic matter that can then be used to enrich garden soil. So, you need to feed those microbes.

In addition to water and oxygen, the microbes need roughly 25 to 30 times as much carbon as nitrogen. So, when we talk about what to put in a compost pile, we talk about carbon-to-nitrogen (C:N) ratios.

“Brown” materials, like fallen leaves, have relatively high C:N ratios. “Green” materials, like fruit and vegetable scraps, have relatively low C:N ratios. You need some of each for composting to occur in a timely manner.

Sometimes, people ONLY put food scraps or ONLY put yard waste in a compost bin. Neither of these situations are ideal. Both can result in a compost pile in which things don’t break down for a long time, since the microorganisms that do the work don’t have what they need.

If you don’t have trees that drop their leaves in the fall, there are other “brown” materials that you can use. You can shred paper or even cardboard. If you do this, you won’t need as much, by weight, as you would of leaves, since paper and cardboard have higher C:N ratios than fallen leaves do.

Turning a compost pile is important for mixing “brown” and “green” materials and for even distribution of moisture and oxygen. If you don’t turn a compost pile, the materials will still decompose eventually, but it will take longer.

For those who would like to learn more about composting, LSU AgCenter extension agents in the Greater New Orleans created a Home Composting Certificate Course that can be completed at your own pace.

The AgCenter also has fact sheets related to composting on our website (www.lsuagcenter.com) or available by request, including Backyard Composting: Waste to Resources, Basic Principles of Composting: What is Composting, Troubleshooting Your Compost Pile, and a series of publications in the Backyard Composting series about different types of composting structures or methods, including the following: Cinder Block Bin, Cinder Block Multiple Bin, Compost Mound, Garbage Can Composter, Wire Mesh Bin, Wooden Box Bin, Wood and Wire Three-Bin Turning Unit, and Worm Composting Bin.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Dealing with Privet Problems

Chinese privet (Ligustrum sinense) is, unfortunately, a common plant in the southeastern US. It spreads by both seeds and root suckers and often crowds out native woodland plants.

In wooded areas, Chinese privet often grows near yaupon holly, which is one of our native shrubs. It’s easy to confuse the two plants from a distance. However, the leaves of yaupon holly are arranged alternately on the stem, while those of Chinese privet have opposite arrangement (i.e., pairs of leaves are situated directly across from each other). Fruits of yaupon holly are red, while those of Chinese privet are dull black.

You’re likely familiar with Japanese privet (Ligustrum japonicum), which is commonly grown as an evergreen hedge in the southeastern US. You may also have seen glossy privet (Ligustrum lucidum). Both of these have larger leaves than Chinese privet. Glossy privet grows taller than Japanese or Chinese privet and, like Chinese privet, often spreads by seed to an undesirable extent.

LSU AgCenter research found that an herbicide with the active ingredient metsulfuron methyl was effective when applied to the leaves of Chinese privet between June and September. Several 60 percent metsulfuron methyl products – including MSM Turf, MSM 60, Escort XP, and Romestol – are available for use on non-crop sites. (See labels for details about what other types of sites these herbicides can be used on.)

Another option is to cut Chinese privet stems near the base and apply a triclopyr-containing herbicide on the freshly made cuts to prevent the stumps from resprouting. For example, one quart of Garlon 4 Ultra can be mixed with 3 quarts of diesel and applied in this manner on non-crop or forested sites. A similar mixture using Remedy Ultra, which is labeled for pasture use, worked well when applied to cut stumps in January.

Anytime you use an herbicide or other pesticide, read the label to make sure it’s suitable for the situation in which you intend to use it, and follow label directions.

Not all Chinese privets are troublesome. A cultivar called ‘Sunshine’ has yellow to light green leaves and, importantly, is sterile. In other words, it doesn’t produce seeds. It’s been used along with purple-leafed loropetalum for a “purple and gold” effect on LSU’s campus. If ‘Sunshine’ is grown in the shade, the leaves are darker green and look more like those of wild-type privet.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Sometimes, Gardening is for the Birds

Birds need food, water, and shelter. Gardens can provide all of these. As we approach fall, which is generally considered the best time to plant most trees and shrubs of temperate origin (i.e., not ones that are marginally cold hardy) in Louisiana, you might consider some plants that support birds.

Many types of trees and shrubs provide shelter and nesting sites. Evergreen plants have the additional benefit of providing shelter in the winter. Including plants of various heights may help draw a greater diversity of birds.

Fruit- and seed-producing plants provide food for many types of birds. Such trees include American holly, eastern redcedar, mayhaw, parsley hawthorn, magnolias, oaks, pines, sweet gum, native plums, and wild black cherry. A fruit producer that might not be as obvious is cabbage or sabal palm.

Shrubs that produce bird food include American beautyberry, arrowwood viburnum, cultivated and native blueberries, elderberry, mulberry, various fruiting hollies, Japanese yew, and wax myrtle.

This article is largely about trees and shrubs, but many herbaceous (non-woody) plants support birds, too. Blackeyed Susan and sunflower are just a couple of many examples that could be named. They may not be at their most attractive point once they’ve finished flowering and have seedheads, but it’s at this stage that they provide food for seed-eating birds.

Hummingbirds consume flowers’ nectar. Red, pink, and orange flowers, as well as those with a tubular shape, are especially attractive to them. Some plants that entice hummingbirds are bottlebrush, red buckeye, coral honeysuckle, firebush (including Lime Sizzler, which has been named a Super Plant), cigar plants, cardinal flower, scarlet or blood sage (Salvia coccinea), and Turk’s cap.

Bottlebrush varieties vary with respect to their cold hardiness, and some are often injured in very cold winters. Woodlanders Red (AKA Woodlanders Hardy) is one of the most resilient. Bottle Pop Neon Pink bottlebrush has also performed well at the Hammond Research Station. As with root-hardy tropicals, it’s probably best to wait and plant this shrub in the spring.

Some birds consume insects, small reptiles, amphibians, or even small mammals rather than fruits, seeds, or nectar. Plants also provide habitats for these. Having some native plants in the garden helps support insects that are more likely to be the foods of choice for native birds.

The Baton Rouge Audubon Society is partnering with the LSU AgCenter Hammond Research Station for a Hummingbird Celebration on September 20, 2025, from 8 AM to 1 PM. The event will include education about and sales of plants that support hummingbirds.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Cosmos Provides a Splash of Color

Louisiana Master Gardener volunteers maintain the beds in front of the LSU AgCenter office in Amite. They’ve been beautiful lately, with orange, pink, red, and blue flowers, in addition to the purple flowers of the ‘Shoal Creek’ chaste trees in front of them. One flower that’s present in abundance is yellow cosmos, which reseeded itself from last year’s plants.

I generally favor perennials, because I like plants that provide multiple years of returns on my planting investment. However, the beauty provided by annual flowers like cosmos is undeniable. Furthermore, cosmos, like their zinnia relatives, often reseed themselves. They also support pollinators such as bees and butterflies and can be used as cut flowers, though their vase life is somewhat short.

Cosmos are in the aster family with sunflowers, black-eyed susans, zinnias, and many other beloved flowers. Two kinds are commonly grown.

Yellow cosmos (Cosmos sulphureus) flowers tend, as one might expect, to be yellow or orange, while those of garden cosmos or Mexican aster (C. bipinnatus) are often pink, red, or white. However, there is some crossover in flower colors, and the shapes of the leaves are probably a more reliable way to distinguish between the two species. Yellow cosmos leaves remind me of ragweed. Garden cosmos foliage has a more delicate, lacy appearance.

Both species are native to Mexico, with the native range of yellow cosmos extending into Central America.

Cosmos can be seeded or transplanted in spring, after the last frost. If sowing seeds, wait until soil temperatures have reached about 65 degrees F or greater. Plant on a well-drained site with full to partial sun exposure.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Early Bird Gold and Goldsturm are Deserving of Super Plant Status

Each year, the LSU AgCenter names several Louisiana Super Plants. Plants chosen for this designation are expected to perform well in the state.

Two varieties of Rudbeckia fulgida, Early Bird Gold and Goldsturm, are among the 2026 selections. This species is sometimes called orange coneflower or black-eyed Susan. One of my favorite things about these plants is that they tend to be reliably perennial in Louisiana, returning year after year. Note that the name black-eyed Susan is more commonly used for the closely related R. hirta, which isn’t as reliably perennial, though it often comes back from seed.

Orange coneflower isn’t considered native to Louisiana, per se, but it is native to several states in the Deep South, as well as other states in the eastern US.

Goldsturm has been around for many years, having been selected in 1937, and can be freely propagated. Early Bird Gold is a much newer introduction. A specimen with unique characteristics was noticed growing among Goldstrum plants at Dupont Nursery in Louisiana and patented as Early Bird Gold in 2009.

Early Bird Gold is more compact than Goldsturm and starts flowering earlier, around mid- to late May. Goldsturm begins blooming in late June to early July and can continue through late August, while Early Bird Gold tends to be well past its peak by late July. Having both varieties gives you a longer season of flowers.

Plant these on a well-drained site with full sun to partial shade.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Pesticide Safety and Effectiveness Tips

It’s that time of year when we hold recertification meetings for private pesticide applicators. These are people who are certified to buy restricted use pesticides and use them on property they own or lease. They have to attend a meeting approved by the Louisiana Department of Agriculture and Forestry once every three years to maintain their certification.

I thought it might be a good time to review some basics of pesticide safety and effectiveness with you, too. These tips are related to protecting the pesticide applicator; the people, animals, and plants around where the pesticide is applied; the people who will eat the food from plants it’s applied to (as applicable); and the environment in which we live. They also affect whether the product is effective for the purpose for which it’s intended.

Note that when we say pesticides, people sometimes think just of insecticides, but “pesticides” also include herbicides, fungicides, miticides and other similar products.

One of the most important concepts related to pesticide safety is, “The label is the law.” Federal and state law require that we follow the directions on pesticide labels. This covers things such as using them only on plants, animals, or sites (as applicable) that the label allows us to use them on; wearing protective clothing specified on the label; not using a rate higher (or lower, when a range is given) than the label allows; and not using them more often or closer to harvest than the label says we can.

Another important concept is that the cause of a problem should be correctly identified before a pesticide is used. Oftentimes, when a plant looks “sick,” the cause is related to non-pest causes. Examples include stress from heat, cold, lack of water, or too much water; improper plant selection (e.g., plants not suited to our climate or how wet or dry or sunny or shady the site is); soil compaction; injury from string-trimmers; etc.

Likewise, there are many types of pesticides and many types of “pests,” and any given product is only effective against a relatively small subset of them. For example, if the cause of plant disease is a bacterial pathogen, a product that only has fungicidal activity isn’t going to help. Furthermore, not every plant pest problem can be helped with a pesticide, and sometimes once a problem is obvious enough that people notice it, it’s too late for a pesticide to do any good.

Before wasting money on something that isn’t going to help your issue, make sure the problem is diagnosed correctly. Let us know if we can help you with this.

Finally, it’s useful to know that companies are not required to prove that a product is effective on a particular insect, disease, weed, etc., before listing it on a pesticide label. Therefore, it’s important to have sources, such as the LSU AgCenter, from which to get research-based information about what products work well on what pests.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu, 985-277-1850 (Hammond), or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Tangipahoa and Washington Parish Are Among Top-Ranking Parishes for Horticultural Crops

For each calendar year, LSU AgCenter Extension agents submit estimates of a variety of agriculture-related values – acres and yields of crops, acres of hunting leases, numbers of farm animals, etc. – for the annual Louisiana Summary: Agriculture & Natural Resources, which we usually call the AgSummary. I’m in the process of preparing estimates of the 2025 horticultural crop numbers, so it’s on my mind. I thought some of you might be interested in knowing more about some of these values. Since the 2024 AgSummary is the most recently published one, numbers are from that year, unless noted.

The area spanning Tangipahoa and Washington Parishes is a great place to be a horticulture-focused Extension agent for someone like me who likes working with commercial horticultural crops.

As many people are aware, Tangipahoa Parish is famous for strawberries, and Washington Parish is known for watermelons. Indeed, Tangipahoa ranks first in Louisiana for strawberries, with approximately 145 acres, while Washington ranks first for watermelons, with an estimated 225 acres. These two parishes also rank near the top in combined fruit and vegetable acreage (not counting sweet potatoes or pecans, which are counted separately in the AgSummary).

Besides edible horticultural crops, Tangipahoa and Washington are also near-top-ranking producers of nursery crops. By 2024 AgSummary numbers, Tangipahoa and Washington Parish rank second and third, respectively, by harvested acreage. According to 2022 USDA Census of Agriculture numbers, the order is reversed for the value of sales (for “Nursery, greenhouse, floriculture, sod”), with Washington ranking second and Tangipahoa third. (Rapides Parish, where the Forest Hill nursery area is located, is first in both cases.)

Dairy is outside of my area of responsibility, but Washington and Tangipahoa Parishes rank first and second, respectively, in Louisiana by all of the following measures: milk production and total dairy gross farm value (value of dairy animals and milk production) in the 2024 AgSummary and, in the 2022 Census of Agriculture, for the sales value of cow milk.

It will be a while before the 2025 AgSummary is published, but you can access those from 2024 and preceding years, going back to 2004, on our website. The USDA Census of Agriculture is only conducted every five years, and the most recent one was done in 2022. You can search “county”-level data for a lot of interesting information.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

When Fig Leaves Look Under the Weather

Figs are one of our more easy-to-grow fruit plants. Unlike more challenging crops like apples and peaches, they can often be grown without a lot of attention to disease and insect management.

By choosing fig varieties like ‘Celeste’ and ‘LSU Purple’ that have a closed “eye,” problems with sour rot and splitting can largely be avoided.

At this time of year, though, leaf diseases often show up. Fig rust is a well-known problem. It causes numerous small brown spots on the upper sides of leaves and slightly raised spore-producing areas on the undersides. Tiny fly larvae that feed on rust spores are often present.

There are also leaf spot diseases of fig that are caused by fungi in the genera Cercospora and Colletotrichum. The spots caused by these fungi are typically larger than those caused by rust.

Distinguishing among these three leaf spot diseases is not all that important in practice. They can all cause leaves to fall off the plant earlier than they normally would, and management practices are similar.

Space fig trees at least ten feet apart when planting. Twenty-foot spacing will allow for even better air movement through the canopy. More air movement can contribute to faster drying of leaves and thus less disease.

Along the same lines, when you prune in late winter, prune to allow air circulation through the canopy. Avoid watering from overhead (e.g., with a sprinkler), particularly in the late afternoon and evening. Rake up and remove fallen, diseased leaves.

The good news is that, even when leaves drop during the summer because of rust or leaf spot diseases, fig trees often perform well the following year.

Another group of fig leaf diseases includes the closely related web blight and thread blight. When plants have one of these diseases, a mat of brown fungal growth can frequently be seen on the undersides of the leaves. Some leaves take on a blighted appearance, hanging shriveled on the plant, and fungal growth is often seen on the surfaces of branches close to diseased leaves. Fruit can be infected, as well. If left unmanaged, dieback may occur on a large proportion of the plant.

When one of these leaf blight diseases is present, remove plant parts, including branches, that have fungal growth on them. Management practices that promote air movement and reduce leaf wetness – as mentioned for leaf spot diseases – are also advised.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Troubleshooting Raised Bed Problems: Part 1

Many of us grow vegetables and other plants in raised beds. They’re helpful where drainage is poor. Even where it isn’t, they can make weed management easier and reduce the amount of bending required to grow a garden.

However, raised beds are not always without problems. I’ve had a couple of calls recently from people who had, I suspect, used too much high-nutrient material and ended up with beds that had excessively high salt contents. When we speak of salt in this context, we’re not talking about table salt but about many types of ions, including plant nutrients, that can contribute to salt stress for plants.

The materials used in a raised bed also affect pH. Most vegetables do well between pH 6.0 and 6.5, so gardeners should be cautious about materials that are much more acidic or alkaline.

When building a raised bed, it’s helpful to include some organic materials that have high levels of plant nutrients, but consider the amount that you’re using. Composts vary widely in their contents. Those made from animal manures sometimes have high nutrient and salt contents, while those made from yard waste often have relatively low nutrient levels. (Manure-based composts also bring to mind microbe-related food safety, but I won’t try to address that here.) Mushroom composts tend to have high salt contents and high pHs. These types of materials can be good in moderation, but they usually need to be blended with other, low-nutrient materials.

When people run into problems with their raised beds, they sometimes send the substrate for testing as a routine soil sample. The process used to test soil was developed for field soil (mixtures of sand, silt, and/or clay, with a small amount of organic matter). When these procedures are used on mixtures made up primarily of organic materials, as most raised bed substrates are, the results do not accurately reflect what the plants experience. The nutrient contents shown in these soil reports from raised beds are often much higher than what the plants will be exposed to in the short term.

The LSU Soil Testing and Plant Analysis Laboratory suggests sending substrates that are less than 20% field soil as potting mix samples instead of soil samples. Routine potting mix samples cost $15 each instead of the $11 it costs for a routine soil sample, and the test used requires a greater volume of material.

Potting mix sample reports include results for pH and for concentrations of nitrate, phosphorus, potassium, calcium, magnesium, and soluble salts. The reports provide interpretations of the results, such as “low,” “very high,” and “optimum,” which are helpful when troubleshooting. However, they don’t provide recommendations about how to fertilize, so you may need to contact us for guidance.

In the next article, I’ll write about a couple of other issues people encounter.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Revisiting Viburnums

Viburnums, as a group, have long been a bit nebulous to me. My interest in them was piqued recently when I purchased a southern arrowwood (Viburnum dentatum) from the Tangipahoa Parish Master Gardener Association at the LSU AgCenter Hammond Research Station’s Fall Garden Day and Plant Sale. I chose the variety ‘Ben’s Creek’ because of its origin. It was propagated from a plant collected by nurseryman Rick Webb near its namesake in Washington Parish. Of course, I want all the plants named after locations in my home parish. (I already had ‘Bogalusa Highway’ yaupon.)

Southern arrowwood is native to much of the eastern US. Within Louisiana, it’s found in the Florida Parishes and the western half of the state. Southern arrowwood is deciduous and grows to approximately 8 feet tall, though it can get larger. Like many viburnums, it produces a flower cluster with white petals in the spring. The flower clusters reach 4 to 5 inches wide. Blue-black fruits suitable for birds form if adequate cross-pollination occurs. The plant can grow in partial shade to full sun. In the wild, southern arrowwood is often found in moist woods and along stream banks.

Another viburnum native to the Florida Parishes is possumhaw (V. nudum). (Note that this is different from the deciduous holly, Ilex decidua, that’s also called possumhaw.) This plant tends to grow on wetter sites than southern arrowwood does. Like southern arrowwood, possumhaw is deciduous and produces a white (or off-white, for possumhaw) flower cluster in the spring. It sometimes flowers in the fall, too. Fruits turn from green to pink to blue-black over time. Possumhaw has smoother leaf margins than other native viburnums, and leaves tend to be glossy. It typically reaches about 10 feet tall but can grow larger.

Several other viburnums – including mapleleaf viburnum (V. acerifolium), blackhaw (V. prunifolium), and rusty blackhaw (V. rufidulum) – are native to Louisiana but more commonly found in the northern half of the state.

Among non-native viburnums, one of the best-known in Louisiana is Chinese snowball viburnum (V. macrocephalum). In spring, this shrub produces flower clusters that resemble those of panicle hydrangeas but are more rounded. Petals are light green when they first appear and become white over time. Chinese snowball viburnum sometimes flowers in fall, also. It can grow to 15 feet tall or greater. Flowers are sterile so, unlike most other viburnums, it does not produce fruit. Leaves are semi-evergreen in Louisiana.

Another viburnum planted in southern Louisiana is sweet viburnum (V. odoratissimum). This is a fast-growing evergreen shrub that’s sometimes used as a hedge. It can grow to approximately 15 to 20 feet tall. Sweet viburnum sometimes experiences cold damage in USDA Hardiness Zone 8. Like other marginally hardy plants, it shouldn’t be pruned or fertilized in late summer, since these activities can encourage growth that lacks cold hardiness.

‘Mrs. Schiller’s Delight’ viburnum is a Louisiana Super Plant. It’s a cultivar of the species known as small viburnum, Walter’s viburnum, or small-leaf arrowwood (V. obovatum). The species is considered native to the southeastern US though not to Louisiana. The small viburnum gets its name from the size of the leaves. The plant itself can get quite large. ‘Mrs. Schiller’s Delight’, however, is a compact variety that reaches approximately 5 feet tall if unpruned. The white flower clusters are not as large as those of some viburnums, but ‘Mrs. Schiller’s Delight’ produces an abundance of them in spring. It grows in partial shade to full sun, but afternoon shade is likely beneficial. The plant is considered evergreen in Louisiana.

I’ll make a final note about viburnums in general. One characteristic that’s often used when identifying plants is leaf arrangement. Alternate leaf arrangement is most common, with opposite and whorled arrangement being less so. Because viburnums have oppositely arranged leaves – meaning that two leaves will occur across from each other on stems – this can be helpful in the process of determining if a plant is a viburnum or not.

Let me know if you have questions.

Click here for previous LSU AgCenter's Weekly Messages

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).

LSU AgCenter's Weekly Message

Growing Your Own Vegetable Transplants

It may be hard to imagine it right now, as we just came through come of the coldest temperatures many of us have ever seen in Louisiana, but it is or will soon be time to prepare to plant warm-season vegetables.

It’s not at all too early for things like soil sampling and, if needed, liming. If you plan to grow your own transplants, it will soon be time to seed them.

It takes about 8 to 10 weeks to grow tomato, pepper, and eggplant transplants in the winter for spring planting and about 3 to 4 weeks to grow cucumber, squash, cantaloupe, and watermelon transplants. To decide when to start seeds, count back from when you plan to transplant the seedlings into the garden.

One of the main perks of growing your own transplants is that you can choose from a more diverse range of vegetable varieties than those offered for sale locally as transplants. You can try ones recommended for this area by the LSU AgCenter, or you can branch out and try others. Varieties not previously trialed nearby may result in failure, or they may be your new favorite. When possible, look for ones with resistance to diseases common to our area.

Growing transplants does require labor and supplies, so take this into account when deciding whether to grow your own.

Not all vegetables are good candidates for transplanting. Among warm-season crops, corn, beans, and peas are almost always direct-seeded. On the other end of the spectrum, tomatoes, peppers, and eggplants are almost always transplanted. In the middle are cucurbits (cucumbers, squashes, etc.), most of which establish well when direct seeded (triploid or seedless watermelons are an exception) but can be grown from transplants for an earlier harvest.

Various containers can be used to start seeds. Options include reused things like egg cartons and cut-up half-and-half containers, biodegradable peat pots, expandable peat pellets, and the plastic cell packs in which transplants are often sold. Containers with 1.5-inch-wide cells are appropriate for most vegetables.

Regardless of the type of container you use, be sure it is clean and has adequate drainage holes. If you reuse cell packs, clean them and then sanitize using a 10 percent bleach solution or other product labeled for this purpose.

Germination or seed-starting media typically contain fine particles of peat moss and perlite. Use sterile media to avoid problems with diseases and other pests. Water it well before planting seeds.

Vegetables have different optimum temperatures for seed germination and growth. Temperatures between 70 and 75 degrees F during the day and about 65 degrees F at night are good for most warm-season vegetables. “Seedless” (triploid) watermelons are an exception. For these, the temperature should not get below 70 degrees F, and temperatures between 85 and 90 degrees F are recommended.

If you have a home greenhouse, make sure to ventilate it adequately during the day so that transplants don’t get excessively hot. This can happen even in winter.

Plants need adequate light. To grow transplants inside a house or apartment without grow lights, you’ll need a spot with very bright light coming through the window.

Seedlings also need an adequate but not excessive amount of water. Lifting transplant containers is often helpful when determining if they need water or not. When they feel lightweight, they likely need to be watered.

Use of a water-soluble 20-20-20 fertilizer, beginning when seedlings have their first true leaves, is often recommended. These fertilizers can be ordered. Alternatively, a half-and-half (1:1) mixture of the 24-8-16 and 15-30-15 water-soluble fertilizers commonly found in stores would produce a 20-19-16 fertilizer, which would probably be satisfactory. A dilute mixture of such fertilizer (approximately 1 teaspoon per gallon of water) could be applied once per week, or an even more dilute mixture (1 teaspoon in 5 gallons of water) could be used each time they’re watered.

When you get close to the time you plan to plant in the garden, take steps to harden off transplants.

While you prepare for your spring garden, keep in mind that you still have time to plant many cool-season vegetables. We can garden year-round in Louisiana.

Let me know if you have questions.

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Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).