Tomato tutorial



Spring is here, and it’s time to think tomatoes. Consider the following information to get the best possible crop.

Tomatoes are categorized by maturity class (early, mid-season or late), fruit size (cherry, pear, plum or large), plant size (determinate, semi-determinate or indeterminate), fruit color (red, pink, yellow, orange), or use (fresh, process or dual use). When selecting varieties, consider the growing environment, primary use and available growing space. Most garden centers and nurseries carry varieties that have been proven to grow well and produce high quality, flavorful fruits for local conditions. Tomatoes can be grown from seeds or transplants. Transplants should have about five to seven mature leaves and a well-developed root system. Transplants mature about four weeks before seeded tomatoes and are recommended for most growing areas of Utah. Tomatoes prefer a sunny location and fertile, well-drained soils. Incorporate plenty of organic matter and a complete fertilizer into the area before planting. Once planted, avoid heavy fertilization, which encourages excessive foliage growth and delays fruit maturity. Side dress with nitrogen (34-0-0) using one tablespoon per plant at four and eight weeks after transplanting.

Plant tomato seeds directly in the garden 10-14 days before the last frost date. Most gardeners transplant tomatoes through black plastic for earlier maturity. Use row covers or hot caps to protect the plants when transplanting before the frost-free period. Plant tomatoes two feet apart in the row with rows spaced two to three feet apart. Plant three to four tomato plants per person for fresh use and an additional five to 10 plants for juicing, canning or freezing. Expect 100 lbs. of fruit per 100 feet of row. Irrigation should be deep and infrequent. Apply one to two inches of water per week. Use drip irrigation if possible. Mulch placed around the plant will conserve soil moisture and reduce weed growth. Do not apply organic mulches until soils have warmed to 75 F. Irrigate so that moisture goes deep into the soil. Irregular watering (over or under) can cause blossom-end rot, a dark leathery spot on the bottom of the fruit. Use wooden stakes or wire cages to support the plants and keep ripening fruits off the ground. Stakes should be driven 18 inches into the soil, three to four inches from the stem. Indeterminate varieties require more support and vine pruning to keep plant size manageable. Continue to tie up plants as they grow. Control insects and diseases throughout the year. Common problems are tomato horn worm, aphids and fusarium and verticilium wilt. Consult your local county Extension office if plant problems occur. Tomatoes require 25-35 days to mature from flowering, depending on the temperature and variety. For the best flavor and quality, pick fruits when they are fully colored but firm, and pick as they ripen. At the end of the season, harvest all fruits that are mature green or colored slightly. Store at 55 F and use as they ripen. Ripe tomatoes will store for one to two weeks if held at 50-55 F. Fruits are subject to chilling injury, so do not store them for more than a few days in the refrigerator.

The following are answers to recent tomato questions.

Q: What causes the flowers to drop off my tomato plants? A: During unfavorable weather (night temperatures lower than 55 F, or day temperatures above 95 F), tomatoes do not set and flowers abort. The problem usually disappears as the weather improves.

Q: What can I do to prevent my tomatoes from cracking? A: Some varieties are more prone to cracking than others. Many of the newer hybrid varieties are quite resistant. Severe root or vine pruning increases cracking. Keep soil moisture uniform as the tomatoes develop and plant resistant varieties to minimize this problem.

Q: I sometimes see small, cloudy white spots just under the skin of my tomatoes. What causes this? A: These spots on green or ripe fruits are caused by the feeding of stink bugs.

Q: Why are the new leaves on my tomato pointed, cupped, twisted and irregular in shape? A: It is likely that your tomatoes have been injured by 2,4-D or a similar growth regulator weed killer. Never use the same sprayer in your vegetable garden that you use for weed control in your lawn. Use caution when applying lawn care chemicals near vegetables or fruit plantings. If applying grass clippings to the garden, make sure the herbicides used are safe for food plants. Consult with your lawn care professional to ensure the chemicals applied to your lawn will not affect your edible garden plants.

Posted on 30 Apr 2004

Dan Drost
Vegetable Specialist

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