Gardening in Louisiana: zones, frost dates and when to plant

A twelve-month garden

The LSU AgCenter’s Louisiana Vegetable Planting Guide (Pub. 1980) states it plainly: vegetables can be planted year-round in Louisiana. Work the garden as a rotation. When one crop finishes, pull it, rework the row and plant the next. The guide’s example is Irish potatoes dug in May or June followed by peas, okra or sweet potatoes in the same space. It also warns new gardeners not to overdo it, since some of those twelve months are very hot and some are cold.

For continuous harvests, sow bush snap beans, peas and greens a week or two apart. Another option is to plant early, midseason and late varieties at the same time.

North, central, south and coastal Louisiana

The planting guide’s table has spring and fall columns for both south and north Louisiana. For many crops the dates match, but some differ by as much as a month. Central Louisiana falls between the two. The guide tells central gardeners to follow north Louisiana dates in spring and use either set in fall.

Coastal gardens get more room still. The guide notes that gardeners along the coast can often stretch the fall planting season by a month, because freezes there are rare or absent. They can also start transplanting warm-season crops as early as late February.

The LSU AgCenter’s separate “When to Plant” chart for vegetables, herbs and fruits also gives north and south Louisiana their own dates. It frames the purpose as avoiding losses to both freezing temperatures and excessive heat. Use it together with the frost dates for your city above.

Summer heat is the limiting season

In Louisiana the hardest stretch is midsummer, not winter. LSU AgCenter horticulturist Dan Gill writes that tomatoes, beans, cucumbers and squash need mild daytime temperatures in the 70s and 80s to produce well. Midsummer heat reduces the number of flowers that set fruit. Spider mites, leaf miners, beetles and caterpillars build up at the same time and cause more damage as summer goes on.

The LSU AgCenter’s answer is to replace worn-out spring plantings with crops that like heat:

• Okra. In Louisiana it never gets too hot for okra. Direct-seeded in midsummer, it starts bearing in late August or early September and continues until fall weather cools. Clemson Spineless and Cajun Delight are among the reliable varieties.
• Southern peas, such as purple hulls, crowders, cream peas and black-eyed peas.
• Eggplant, which handles mid- to late-summer heat much better than its relative the tomato.
• Hot peppers and sweet peppers such as Sweet Banana, Gypsy and Pimento. Bell peppers usually produce poorly in high heat, but bell transplants set out from late July through August produce in the cooler fall.

Tomatoes: spring crop and fall crop

Louisiana tomatoes have a spring season and a fall season. The planting guide lists recommended varieties by type. Indeterminate choices include Better Boy, Big Beef and Champion, and determinate choices include Celebrity, Bella Rosa and Tribute. A separate heat-tolerant group includes Florida 91, Heatwave II, Phoenix, Solar Fire, Sun Leaper and Sun Master. For the fall crop, buy transplants at nurseries in late July and August or start your own seed in early July. The guide says tomato, pepper and eggplant seed needs 6 to 10 weeks to reach transplant size, with the longer times for the spring crop.

Sun, spacing and soil

Give the garden 6 to 8 hours of sun a day. Fruiting crops such as tomatoes, peppers and squash need full sun. Lettuce, broccoli and cabbage tolerate some shade. Follow the guide’s spacing. Crowded plants attract more insects, spread disease more easily and yield less.

Soil type affects seeding depth. Clay soils crust, so seeds go shallower than in sandy soils. Most vegetables grow best between pH 5.5 and 7. The guide warns against adding lime unless a soil test shows a need for it.

Getting a soil test

Soil tests are run by the LSU AgCenter Soil Testing and Plant Analysis Lab on the LSU campus in Baton Rouge. Sampling kits are available at parish extension offices and nursery retailers across the state. Each kit has an information form, sample bags and a prepaid mailing box. A routine test reports nutrient levels and whether the soil is acidic or alkaline. On the form, list what you plan to grow, and the recommendations will be written for those crops. Results usually take a week to 10 days. The planting guide says to retest at least every three years. LSU AgCenter agents suggest sampling in late summer, ahead of fall planting, because some amendments, such as elemental sulfur, need two to four months to take effect.