Express News Weekly Article
Saturday, April 2, 2005
By Calvin Finch, Conservation Director, SAWS, and Horticulturist

Tomatoes  

            For years, horticulturists in San Antonio have said the most popular gardening topics in our area are the 3 “t’s,” turf, trees, and tomatoes.  At this time of the year, tomatoes are the “t” that is most on every gardener’s mind. 

 

            There are 100’s of selections of tomatoes and every year new hybrids are introduced on the commercial market.  Unfortunately, there is not much research on home gardening tomatoes.  It may seem like home gardeners in San Antonio buy enough tomatoes to merit research to develop the perfect plant for our gardens, but that is not the case.  Our choices for home gardeners are limited to an ever-changing set of commercial hybrids or the inappropriate varieties used from the North.  For 2005:  Heat-wave, Sun Pride, Sun Master, 444, Amelia, Celebrity, Bingo, Carnival, Merced and Whirlaway are available in varying quantities. All are determinate or semi-determinate, which means they grow to a limited size and set fruit quickly.  Such a growth pattern is appropriate for our two-season approach to tomato growing.

 

            In San Antonio, you plant tomatoes in April to harvest fruit in June.  We plant again in late July to harvest fruit in October and November.  The Northern selections like Big Boy or Big Girl are indeterminate.  In our climate, they often grow to huge size without producing much fruit.  Cherry tomatoes are also indeterminate, but they seem to have more capability to set fruit in the heat. 

 

            We wait to plant tomatoes until all danger of frost has passed and the soil is relatively warm.  A tomato transplant placed in the garden in early March may not freeze, but it will probably not grow either.  Tomato plants that stop growing because of cold soil and cool temperatures are very hard to restart.  They will recover, but they produce less.  Many gardeners buy their transplants in early March, but place them in one-gallon containers until April because it is easier to protect them from cold in a container.  A tomato in a pot placed in full sun, but out of the wind, is in its the best place during the month of March.  April plants stepped up to a one-gallon container are large and may even be blooming, ready to take advantage of the April and early May fruit setting weather. 

 

            If you do not have your tomatoes in pots, select large sturdy transplants from the nursery.  Plant them in raised beds or garden soil enriched with compost.  Tomatoes are heavy feeders, so also add one cup of slow release lawn fertilizer like 19-5-9 to every ten sq. ft. of planting area.  Allow three feet between plants.  To keep the fruit off of the ground, place a tomato cage around each plant.  Your favorite nursery sells tomato cages.  The larger the cage, the better for the plant.  Cages made with a seven (7) feet piece of concrete reinforcing wire are especially effective but are hard to find. 

 

 

 

            Mulch over the root system with live oak leaves, pecan shells or some other organic material.  Mulch of one to two inches deep works well.  If possible water with a drip irrigation system.  Drip irrigation is efficient and does a good job of applying the right amount of water.  A tomato loaded with fruit may have to be watered every day or every other day. 

 

            Blossom end rot is a common tomato disorder.  The plant is not able to pull up enough calcium for fruit growth.  The fruit develops a black scar tissue symptom.  Calcium moves into the plant in the water stream, so plants with limited root systems such as those in containers are especially susceptible to blossom end rot.  Some years, almost all plants display some blossom end rot fruit.  This is especially true when the weather changes from overcast and cool to hot and sunny.  Mulch and drip irrigation help reduce the extent of blossom end rot.  Calcium treatments are not effective in most situations because the key is moisture uptake.  There is plenty of calcium in our soil.

 

            Early blight and various caterpillars are also common tomato pests.  To prevent early blight from killing foliage from the bottom up, apply a labeled fungicide such as Daconil every week.  Bt products such as Thurielde, Depel, and Bioworm Control will control caterpillars.  Apply Bt whenever you see any damage.  The worms must consume Bt for it to work.  Plant your tomatoes now for home grown fruit this summer.