Lettuce is a Cool-Season Vegetable
I eat quite a bit of lettuce, and I expect that many of you do, too. Lettuce is not a very demanding vegetable, but it needs to be grown at the right time of year, and some types are easier to grow in our climate than others. Because we’re growing leaves when we grow lettuce, it will still produce in the presence of some shade, and it can be grown in containers.
In Louisiana, we can plant lettuce from mid-September through October and again between late January and early March. Once temperatures stay above approximately 85 degrees F for several days in a row in the spring, it tends to “bolt,” or produce a flower stalk, and become bitter. A bitter taste can result from hot weather alone, as well.
Lettuce varieties are divided into four groups: crisphead (iceberg), romaine (cos), butterhead (including bibb and Boston), and loose-leaf. I consider loose-leaf lettuce the most forgiving: It is generally ready to harvest sooner (in approximately 40 to 50 days) than the other types and, really, if you don’t mind eating smaller leaves, can be harvested anytime. Crisphead lettuce is on the other end of the spectrum. From the time of transplanting, it takes about 70 to 85 days to be ready for harvest. Crisphead lettuce tolerates handling well and has thus long been one of the more common types in grocery stores.
Recommended varieties of the different types follow. Loose-leaf: Grand Rapids, Nevada, New Red Fire, Oakleaf, Red Sails, Red Salad Bowl, Salad Bowl, Sierra, and Tango. Butterhead: Buttercrunch, Caliente, Esmeralda, Harmony, Skyphos, and Summer Bibb. Romaine: Cimarron Red, Cuore, Flashy Trout Back, Green Towers, Ideal, Parris Island Cos, and Red Eye. Crisphead: Crispino, Great Lakes, Ithaca (for spring planting), Keeper, Maverick, and Raider.
Loose-leaf lettuce seeds can be sown directly in the garden, but it’s best to transplant other types. If you grow lettuce from seed – in the garden or while growing transplants – be sure not to plant it too deeply. Some lettuce seeds need light to germinate, so barely cover them with soil. Keep the soil surface consistently moist while seeds germinate and plants get established.
For every 10 feet of row or 30 square feet, 0.5 pound (1 cup) 8-8-8 or 0.33 pound (0.67 cup) 13-13-13 can be mixed into the soil before planting. Side dress plants about 3 to 4 weeks after planting (when leaves are 2 to 4 inches wide) and, if desired, 10 to 14 days after that. Either 0.1 pound (0.2 cup) 33-0-0, 0.15 pound (0.25 cup) ammonium sulfate, or 0.2 pound (0.33 cup) calcium nitrate can be used each time, per 10 feet of row / 30 square feet. (A soil test can be taken to get more information about soil nutrient levels and pH.)
Romaine, butterhead, and crisphead lettuce can be planted 10 to 12 inches apart within a row. Loose-leaf lettuce seeds are often sown thicker than the desired final spacing and thinned to 4 to 12 inches between seedlings. Plant several times to extend the harvest.
Caterpillar pests and aphids can be problematic on lettuce, so watch for these.
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).
Last Thursday (September 26, 2024), the Marion County Sheriff’s Office received information regarding animal cruelty. The information received was in reference to animals being tortured and killed, while being videoed. 
