For The Answer
By Calvin Finch, PhD, SAWS Conservation Director, and Horticulturist
Week of March 1, 2004
It is too early to put your tomato transplants directly into the garden, but it is a good time to pot them up in 1-gallon containers so they will be large and ready for action by April 1.
If you have room for more than one variety of tomato you should select at least two. Every year the weather is a little different and sometimes one variety performs best, the next year another variety will do better. Celebrity is an excellent all-around variety that seems to be reliable most years. My two favorites, however, are Merced and 444. Both respond to heavy fertilization, regular watering, and mulch to produce large crops of baseball-size fruit. None of the heat-setting selections of past years (Surefire, Heatwave or Sun Master) are available anymore; they were hybrids produced for the commercial market that have been replaced so are no longer available to home gardeners either. Other tomato varieties recommended for the San Antonio area are Bingo, Whirlaway, and Carnival.
Plant tomatoes in full sun with 3 to 4 feet between plants. The soil warms up enough about April 1. If you plant too early the plants harden off or even die back.
Potting up is the practice of buying transplants early and planting them in 1-gallon containers filled with high quality potting soil and Osmocote or other slow-release fertilizer for containers. Place the pots in a sunny location out of the wind. If temperatures are forecast to drop below 40 degrees F. in an evening, move the pots in the house.
Potting up allows you to take advantage of the short window of ideal fruit setting weather that we have in San Antonio. The plants in the pots grow fast and should be in the bloom stage by April when they can be placed in the garden just in time to set fruit before the weather gets too warm. Surround your transplants with a tomato cage to keep the fruit off of the ground.
Organic gardeners can also use the cage as a frame to drape Gro-Web or other agricultural fiber over the plant. Gro-Web, if sealed tight with clothespins, will exclude thrips and other insects from the plant. Thrips carry disease such as the spotted wilt virus. The fabric lets in the sun and also provides a few degrees of cold protection in case we receive a late freeze. Remove the fabric when the foliage fills out the cage. The plants are safe from the virus by then.
Tomatoes are not xeriscape plants but, if you mulch them with 2 or 3 inches of live oak leaves, compost, or grass clippings and use drip irrigation, they will not waste water. When it is warm and they are loaded with fruit, they must be irrigated every two days.
Tomatoes can be grown in containers as well as in the garden. A half whiskey barrel is ideal for one plant. If you use anything less they will have to be watered at least once per day. A 5-gallon container is the smallest recommended container. Fertilize tomatoes in containers once per week with a soluble (water dissolved) fertilizer.
Tomatoes grown in the garden can be fertilized with soluble fertilizers but it is less expensive and just as effective to apply a half-cup of slow-release lawn fertilizer such as 19-5-9 around the plant every four weeks.
If you are looking for a fun event this weekend or next, plan on attending one of the Spring Bloom Giveaways. The Spring Bloom Giveaways will be held on Saturday, March 6, in front of the Whole Foods at the Quarry, and on Saturday, March 13, at the CPS Education Center located at 509 SW Military Dr., from 9 a.m. until noon. Every person who attends age 15 and older will receive one free 3-inch blooming xeriscape plant (dwarf ruellia, lantana, or society garlic) on a first-come first-served basis. It is also a good event to get all your xeriscape and gardening questions answered. I will be available at each site. The Gardening Volunteers of South Texas will also be on hand to sell Jerry Parsons’ experimental plants.