LSU AgCenter's Weekly Message

Growing Blueberries Can Be Easy with Good Site Selection and Preparation

In the last two articles, I’ve discussed 2024 yields and harvest dates from the blueberry variety demonstration at the Hammond Research Station.

While the main purpose of this planting is to demonstrate the performance of different blueberry varieties in our climate, I’ve found that one of its major uses has been as a springboard for talking about how to prepare the soil for planting.

Rabbiteye blueberries can produce for many years and with relatively little care if a good site is chosen and the soil is prepared well. Try to find a site with full sun exposure and good drainage.

Where we planted blueberries, sulfur was applied based on soil test results several months before planting to reduce pH. This oftentimes isn’t necessary in southeastern Louisiana, where soil pH tends to be naturally acidic, but these rows had previously been limed for another crop. The target pH for blueberries is around pH 4.5 to 5.2, though rabbiteye varieties can tolerate slightly higher pHs (up to about pH 5.5).

Shortly before planting, aged pine bark was spread to a depth of 2 to 4 inches in a 3-feet-wide strip on rows where rabbiteye varieties would be planted. Where southern highbush plants would be planted, the mulch depth was increased to 4 to 6 inches. Mulch was rototilled into the soil, and the soil-bark mixture was hipped into raised rows with discs pulled by a tractor.

After planting blueberries (6 feet apart for rabbiteye plants and 4 feet apart for southern highbush plants), additional pine bark was spread on the tops of rows for weed management. Blueberry plants have shallow root systems, and it’s important to keep turfgrass and other weeds away from the bases of the plants, especially while they’re getting established.

We also installed drip irrigation tubing after planting and before applying the surface mulch layer. This is an option for home gardens, as well, but isn’t absolutely necessary. In a small planting, watering can be done by hand while plants are getting established and during dry periods.

If just a few plants will be planted, pine bark can be mixed into the soil in individual 3-feet-diameter circular areas. In my yard, where I have soil on the heavier side (silt loam), I mix 2 cubic feet of pine bark mulch into the soil prior to planting each blueberry plant. This allows me to plant on a raised mound. Then, I add another 1 cubic foot of mulch on top the mound, around the plant, for weed management and to hold moisture in the soil. Over the years, the area to which mulch is applied can be expanded as the plant grows.

The period between late fall and early spring is a good time for planting containerized blueberry plants, as this allows them to grow some roots before summer heat arrives. Bare root plants should be planted while dormant. Plant at least two varieties for cross pollination.

Wait until spring, when new growth has fully expanded, to fertilize newly installed plants. There are multiple ways to go about fertilizing blueberries, but here are some things to be aware of: Blueberries are sensitive to overfertilization. Ammonium- or urea-containing fertilizers are preferable to nitrate-form nitrogen. Fertilizer should be applied between when plants start to grow in late winter or early  spring and sometime in the summer, after harvest. Don’t concentrate fertilizer at the bases of the plants but spread it out under and a bit out from the canopies.

In the variety demonstration, we have used the following, per bush, since planting in November 2020: 1 tablespoon 13-13-13 (March 2021), 2 teaspoons ammonium sulfate (21-0-0; July 2021), 2 tablespoons 13-13-13 (April 2022), 2 tablespoons ammonium sulfate (August 2022), 0.25 cup 13-13-13 (April 2023), 3 tablespoons ammonium sulfate (June 2023), 0.33 cup 13-13-13 (April 2024), and 3 tablespoons 33-0-0 (urea-ammonium sulfate; August 2024).

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).