Tomatoes: A Growing Guide

A vegetable garden isn't complete without tomatoes.


How to grow the best tomatoesGrowing guidelines
Cultivate lightly to keep down any weeds until the soil is warm, then lay down a deep mulch to smother the weeds and conserve moisture. Give the plants at least 1 inch of water a week, keeping in mind that a deep soaking is better than several light waterings. Avoid wetting the foliage, since wet leaves are more prone to diseases.

A weekly dose of liquid seaweed will increase fruit production and plant health, as will side-dressing with compost two or three times during the growing season.

If you stake your plants, you may want to prune them to encourage higher yields. Pruned tomatoes take up less space and are likely to produce fruit 2 weeks earlier than unpruned ones; they do, however, take more work. Pruning tomatoes is different from pruning trees and shrubs—the only tools you should need are your fingers. You'll be removing suckers, which are small shoots that emerge from the main stem or side stem at the base of each leaf.

Leave a few suckers on the middle and top of the plant to protect the fruit from sunscald, especially if you live in a hot, sunny area, such as in the South. Sunscald produces light gray patches of skin that are subject to disease. When the vine reaches the top of the stakes or cage, pinch back the tips to encourage more flowering and fruit.

Helpful hint for pinching tomato suckers
Use your thumb and forefinger to snap off the small, tender shoots that sprout at the base of tomato leaf stems. If you need to use scissors or pruning shears, you've waited too long.

Although tomatoes are potentially subject to a range of pests and diseases, plants that are growing in rich soil with adequate spacing and support to keep them off the soil usually have few problems. Here are some of the common potential tomato problems:

  • The tomato hornworm—a large, white-striped, green caterpillar—is an easy-to-spot pest. Just hand pick and destroy, or spray plants with Bt (Bacillus thuringiensis). If you're hand picking, check to see whether horn-worms have been attacked by parasitic wasps first—if they have, the wasp larvae will have pupated, forming structures that look like small white grains of rice on the back of the hornworm. Leave these hornworms be so the wasps can spread. Also, plant dill near your tomatoes. It attracts hornworms, and they're easier to spot on dill than they are on tomato plants.
  • Aphids, flea beetles, and cutworms may also attack your tomato plants. 
  • Hard-to-spot spider mites look like tiny red dots on the undersides of leaves. Their feeding causes yellow speckling on leaves, which eventually turn brown and die. Knock these pests off the plant by spraying with water, or control with insecticidal soap.
  • If you are new to growing tomatoes, check with your county extension agent to find out what diseases are prevalent in your area. If you can, choose varieties that are resistant to those diseases. Such resistance is generally indicated by one or more letters after the cultivar name. The code "VFNT," for example, indicates that the cultivar is resistant to Verticillium (V) and Fusarium (F) wilts, as well as nematodes (N) and tobacco mosaic (T).
  • Nematodes, microscopic wormlike creatures, attack a plant's root system, stunting growth and lowering disease resistance. The best defenses against nematodes are rotating crops and planting resistant cultivars.
  • Verticillium wilt and Fusarium wilt are two common tomato diseases. Should these wilts strike and cause leaves to curl up, turn yellow, and drop off, pull up and destroy infected plants, or put them in sealed containers and dispose of them with household trash.
  • Another disease, early blight, makes dark, sunken areas on leaves just as the first fruits start to mature. Late blight appears as black, irregular, water-soaked patches on leaves and dark-colored spots on fruits. Both blights tend to occur during cool, rainy weather. To avoid losing your whole crop, quickly destroy or dispose of affected plants. The best defense is to plant resistant cultivars. Bicarbonate sprays can also help prevent the disease from infecting your plants.
  • Blossom drop, where mature flowers fall off the plant, is most prevalent in cool rainy weather or where soil moisture is low and winds are hot and dry. It can also be from a magnesium deficiency or from infection by parasitic bacteria or fungi. Large-fruited tomatoes are particularly vulnerable. Fruit set can sometimes be encouraged by gently shaking the plant in the middle of a warm, sunny day or by tapping the stake to which the plant is tied.
  • Blossom-end rot appears as a water-soaked spot near the blossom end when the fruit is about 1/3 developed. The spot enlarges and turns dark brown and leathery until it covers half the tomato. This problem is due to a calcium deficiency, often brought on by an uneven water supply. Blossom-end rot can also be caused by damaged feeder roots from careless transplanting, so always handle seedlings gently. Try to keep the soil evenly moist by using a mulch and watering when needed.
  • Prolonged periods of heavy rainfall that keep the soil constantly moist can cause leaf roll, which can affect more than half the foliage and cut fruit production significantly. At first, the edges of leaves curl up to form cups; then the edges overlap and the leaves become firm and leathery to the touch. Keeping soil well drained and well aerated is about the only method of preventing this problem.
  • Fruit with cracks that radiate from the stems or run around the shoulders are often caused by hot, rainy weather or by fluctuating moisture levels in the soil. Such cracks, aside from being unsightly, attract infections. To avoid them, make sure you don't overwater.
  • Tomatoes—like eggplants, potatoes, and peppers—are related to tobacco and subject to the same diseases, including tobacco mosaic. Therefore, don't smoke around such plants, and wash your hands after smoking before handling them. Plan your garden so that nightshade-family crops, such as peppers and tomatoes, are separated by plants from other families.

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