The South Texas Plains stretch from San Antonio west to Del Rio and south to the Mexican border. The Plains cover about 18 million acres of land that once had native grasses and are now home to brush and scrub oak. Vegetable gardening in South Texas is popular but can be challenging, with brutal summer heat and cyclical droughts. However, with care and attention, vegetable gardens can be productive all year in this subtropical region.
South Texas vegetable gardens are located in USDA Hardiness Zones 9A and 9B. This means that nighttime temperatures in the coldest months can drop below freezing. The Texas A&M horticulture extension places South Texas in its vegetable gardening regions IV and V.
The native soil in South Texas is slightly alkaline with areas of acidic clays and loamy soil according to Texas Parks and Wildlife. Rainfall rates range from 20 to 30 inches per year with less rainfall as you move south from San Antonio. The entire area is subject to drought and supplemental watering is necessary for South Texas vegetables gardens.
Your South Texas soil will need amendments to become highly productive. Test the soil first using a soil sampling kit. Texas A&M offers soil testing for a modest fee and will send you a report on your soil within two months. Follow the recommendations of the soil test report for adding organic matter, fertilizer, and pH improving chemicals. Adding compost to the top six inches of vegetable garden soil is essential and should be done one to two weeks before planting.
Spring comes early for South Texas vegetable gardeners. Beets, broccoli, cabbage, carrots, cauliflower, onions and lettuce should be planted in mid-January. Plant your beans, corn, cucumbers, melons, peppers, and tomatoes by early to mid-February. Texas A&M AgriLife suggests the following varieties for the most popular spring vegetables: Contender, Topcrop and Blue Lake 274 bush green beans, Green Magic broccoli, Perlita and TAM Uvalde cantaloupe, and Sunmaster, Solarfire, and Celebrity tomatoes.
Texas A&M Horticulture suggests planting Surefire, Heatwave, Bingo, Merced and Whirlaway tomatoes as early as mid-July if you have the time to provide careful attention to watering and pest control. Less demanding tomato varieties for the South Texas fall garden include Carnival and Celebrity. Tomato and pepper transplants may need some shade until they adjust to the heat and should not be allowed to dry out which usually means daily watering until the roots are established.
Between mid-September and mid-October, plant frost-tolerant varieties of cool season vegetables such as broccoli, cauliflower, cabbage, and lettuce.
Water is a precious resource for South Texas vegetable gardeners. To limit the amount of supplemental water for your garden, add composted materials and mulch around plants. Use soaker hoses beneath the mulch or a drip irrigation system both of which decrease the amount of water lost through evaporation.