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How to Grow Tomatoes

Starts | Garden Beds and Planting | Staking | Pruning | Caring | Problems | Bugs | Harvest


Tomatoes are versatile and will grow in many environments. However, optimally they like a moist, tilled, well-composted soil. Tomatoes prefer sunny locations, with a spacing of at least 18 inches between plants. Ideally, as the vines are relatively weak, they should be supported by stakes or some kind of trellis. They can be picked when they are a bright red and used fresh or may be cooked or canned.

Start In-Doors or Plant From Seed

Tomato plant with garden gloves and hat

As tomatoes are perennial plants they will continue to bear until they are killed by being exposed to temperatures below freezing. For this reason, to maximize yields, it is best to start plants in-doors or in a greenhouse six to eight weeks before projected planting time (after all chance of frost). Tomatoes can be started in peat pots, trays, milk cartons, or paper cups. A pasteurized soil mix should be used to eliminate the chance of bugs or disease. Potting soil can be purchased from a garden center, or garden soil may be used by baking it in an oven at for about an hour. It should be mixed with peat moss and vermiculite.

Put soil in the container, level, and moisten. Place seeds at least 1/2-inch apart. Push seeds down slightly, then cover with about 1/4-inch of soil. To maximize warmth and preserve moisture the container can be covered with a plastic sheet. Place the containers under a fluorescent light or in direct sunlight. The best temperature for germination is . Germination should occur within a few days, at which time the plastic cover should be removed. Now the soil should be kept moist and temperatures between 60 and 75 degrees. If growing lights are used, turn them off at night to give the plants a rest. After about a week the plants can be fed with fertilizer. However, they should only be fed at reduced strength to prevent them from becoming leggy, or worse, burned. One quarter the usual strength is appropriate.

When the seedlings have reached three to four inches, if they have been planted all together in a tray, they should be transplanted to roomier containers. To accomplish this, water the plants the night before. Use a large spoon to scoop out the individual plants and re-pot at least three inches apart or in separate containers. Keep seedlings out of bright sunlight for a day or two. Increase fertilizer to 1/3 of normal strength.

When plants are six to ten inches tall they may be re-potted again. This can be done in a way that helps the plant to develop a more extensive root system. While transplanting, remove all the leaves except the top few. Then plant the tomato seedling as deep in the soil as possible (without covering the top couple inches of stems). Additional roots will sprout from the underground stems.

About ten days before planting time, the seedlings should be hardened off. This is done by taking the seeds out of doors in their containers for longer periods each day. They can then be exposed to direct sunlight, wind, and lower temperatures. At this time, their growth will be slowed, but they will be better for it when the time comes for planting in the garden bed.

Tomatoes can be planted in the garden directly from seed. In temperate climates this will definitely lower crop yields before frost hits in the autumn, and may result in no yield whatsoever. The best method for planting tomato seeds directly is to create mounds with a hoe and plant several seeds in each mound about 1/2-inch down after all danger of frost. Water the soil. The mounds should be about 2 feet apart.

Preparing the Garden Beds or Containers and Planting Tomatoes

In selecting the garden beds for growing tomatoes, it is crucial to choose ground that will be exposed to sunlight at least six to eight hours per day. In northern climes, full sun is best. Tomatoes prefer a pH of 6.0 to 6.8, which is slightly acidic. If the soil is not acidic enough, it can be amended with lime and sulfur.

Soils that are too sandy or contain too much clay can be amended by adding organic matter in the form of compost, leaves, and grass clippings. Organic matter has the effect of holding moisture in sandy soils and creating an avenue for excess water to escape in clay soils.

The soil should be well-worked. It can be turned with a shovel, or a garden fork. Big clumps can be knocked apart with a hoe. For larger gardens, tillers may be appropriate. This process creates a great environment for root expansion, and at the same time destroys many weeds that might try to crowd out the tomatoes.

Compost does a considerable job in providing nutrients for growing vegetables. Nevertheless, when the time comes to transplant tomatoes from containers directly into the ground, it is a good idea to add a bit of fertilizer. Tomatoes may be planted in hills or trenches about 8 inches deep. They should be approximately three feet apart. At the bottom of the trench put a thin band of commercial fertilizer. 5-10-10 is ideal (nitrogen - phosphorus - potassium). Additional organic matter may also be used. Cover the fertilizer with two or three inches of soil. This is to prevent immediate contact between the plant and the fertilizer. The plant should reach down to it eventually with its root system.

The best time to transplant the tomatoes from containers to the garden is in the evening or on a cloudy day. Make sure the soil in the containers is moist before removing the plants. This will help ensure that the soil remains around the roots. If cutworms are a problem a collar of newspaper can be wrapped around the plant from an inch above the soil to an inch below. Working relatively quickly, remove the plant from the container, place in the trench and fill in the soil. This can be done by pinching off all of the lower leaves of the plant and laying it sideways into the trench and covering it over. The part underground will quickly develop roots. Meanwhile the roots will be relatively closer to the surface where they will receive more of the early season heat of the sun. Tomatoes within the row should be spaced 18 to 24 inches apart.

Vertical planting can be accomplished in a similar manner. Instead of laying the tomato plant on its side it is planted deeper in the hole (but still above any fertilizer). This is advantageous in locations with long dry summers. Using this method the plant will be able to access more moisture.

Staking, Caging, and Trellising

If tomatoes are not supported they will grow along the ground. Plants may actually produce more tomatoes this way. However, since the fruit often rests on the ground it is more subject to disease and rot.

How to Plant Tomatoes

When staking a tomato, try to place the stake on the down-wind side of the plant. This ensures when the wind is blowing that the plant is pushed against the stake. Pushed away from the stake there is a greater possibility that the plant could snap off. Tomatoes can grow over eight feet high. Nevertheless, stakes up to five feet should prove sufficient. They should be driven about a foot into the soil, three to five inches away from the plant, placed so as to minimize any root damage. Using cloth, or coated wire or twine in a figure-eight fashion, tie tightly around the stake and loosely around the plant. (Around the plant, try to leave about two inches of slack.) As the plant grows, continue to tie it off at succeedingly higher points.

Cages tend to be more popular than stakes because, once in place, they are relatively easy to use. Cages can be purchased at a garden center, or made from fencing with spaces large enough to reach through to grab tomatoes. Ideally cages should be four or five feet high, and staked into the ground.

Trellising is done in a fashion similar to staking except posts are placed in the ground five to six feet apart and wire is strung between the posts at about one foot intervals. As the plants reach the height of the wires, they are tied to the wires.

Pruning Tomatoes

Pruning is accomplished by pinching off stems or leaves that start out of the crotch between branches. This allows the plant to concentrate on specific stems. To get more stems, simply allow suckers to grow. Pruning helps improve ventilation, preventing rot under very moist conditions. Although pruning may help currently developing fruit, it can reduce yield in the long run. For gardeners in temperate regions, the best time to prune is late in the season when newly developing fruit will be unlikely to have time to fully develop. Pruning can also be wise when a plant gets so tall that it has outgrown stakes or cages.

New plants can actually be started using the pinched off suckers. Simply soak them in water for about two hours, then place in potting soil. When roots have developed, they can be transplanted into the ground.

Mulching, Feeding, and Watering Tomatoes

It is a good idea to cover soil around the plant to help retain moisture, help block weeds, and protect low hanging tomatoes from direct contact with the soil. This is called mulching. This can be done by spreading grass clippings, leaves, hay, or sawdust around the plants. Generally, the thicker the layer the more protection for the root system of the plant. Yet mulches should not be applied too early in the season (in the north, especially, wait until five or six weeks after the tomatoes are in the ground to ensure the soil is sufficiently warmed).

Tomatoes are hungry plants and can benefit from frequent watering in dry seasons and adding a bit of additional fertilizer (one or two times during the season). The National Gardening Association recommends that gardeners stay away from high-nitrogen fertilizers (which encourage big green plants, but few fruits). Fertilizing (or side dressing, as it is sometimes called) can be accomplished when the tomatoes are first formed. One and a half tablespoons per plant of 5-10-10 fertilizer should be sufficient. Scrape a shallow trench about 1 inch deep at a distance of around six inches from the stem. Sprinkle in the fertilizer, then cover it over with soil.

Tomatoes like water, but they do not want to sit in sopping-wet soil. The soil should be kept moist. They like an even water supply. One to two inches of water per week is sufficient for good soil conditions. This amounts to about 60-120 gallons of water for every 100 square feet. Water should soak into the soil at least six to eight inches. The best time to water is early in the day. Watering in the evening can trigger some diseases. It is best to avoid spraying water directly on the leaves.

Tomato Problems

Blossom End Rot is caused by a lack of calcium in the plant and fluctuations in the water supply. It is characterized by a sunken, water-soaked spot. It turns brown or black and begins to grow larger. Calcium chloride can be applied directly to the leaves in a weak water solution.

Cracking in tomatoes can occur during growth spurts caused by extra moisture just after a dry spell. The tomatoes are expanding inside faster than the skin can accommodate them. Best to avoid this problem by maintaining even moisture for plants.

Cool night temperatures can cause blossom drop, where the flowers fall off and fruit does not set. But it can also be the result of persistent temperatures above . This is why it is often difficult to grow tomatoes through the summer in regions of the South and Southwestern U.S.

Leaf roll often occurs after heavy rains, mainly to older leaves. This typically is not harmful to tomato production. However, to reduce its occurrence, place plants in well drained soil.

Too much hot sun can cause sunscald. It is characterized by yellow-white patches appearing on the side facing the sun. As the tomato gets larger, this area gets gray-to-white. Maintaining sufficient foliage is the best prevention.

Early blight is a fungus that first appears as little brown spots with brown and yellow rings around them. This usually occurs in warm and humid weather, mainly attacking the leaves, but the fruits can also be affected. Prevention is the main thing. Clean up all old plant material before winter. Spores grow on old decaying leaves. Make sure that the plants are not crowded and get plenty of air circulation. Late blight hits tomatoes later in the season, also largely during very damp conditions. The fruits get dark-brown spots. The fungus is controlled in the same way as early blight. Leaf spot is also caused by a fungus. Infected leaves get gray or brown spots that grow. Eventually, the leaves fall from the plant. Crop rotation is a good way to keep this fungus at bay. Also, treat as in early blight.

Root knot is caused by nematodes. They create nodes in the roots that restrict moisture and nutrient intake. This, of course, restricts the development of the tomato plant. The best control for nematodes is marigolds planted nearby. The roots of marigolds exude a substance that repels nematodes. This substance can remain in the soil for up to three years.

Damping off and soil rot are two more diseases caused by fungi. Damping off kills young plants making them fall right over. Soil rot begins as a brown slightly sunken spot on the tomato fruit. Both usually occur during wet conditions. This can be avoided by keeping fruits off the ground by staking, caging, and mulching.

Tobacco mosaic virus infects many members of the nightshade family. The leaves become mottled dark and light green. There is also a yellow variety. The virus is spread by handling an infected plant and then handling a healthy plant. Smokers can even carry the virus in cigars or cigarettes, so butts should not be cast into the garden. Infected plants should be destroyed by burning; the virus can survive for several years in dead stems and leaves.

Fusarium and verticillium wilt are caused by yet another fungus. The leaves curl and begin falling off in great numbers. It is best to use tomato varieties resistant to this fungus. Keep beds clean, and do not over-water.

Tomato Bugs and Insects

Image of a Stink Bug

Aphids are a common pest affecting many garden plants. They like to get on the stems of tomato plants to suck out moisture and nutrients. In doing this they often spread diseases. Blister beetles and potato bugs like to eat the foliage. Flea beetles are tiny 1/16th of an inch insects that chew holes in the leaves. They are not much of a danger to older plants, but can strike down seedlings. Stinkbugs also like to suck the juices from tomato stems. Whiteflies can also be a problem. Besides sucking the plant's sap they secrete honeydew (a sugary substance) upon which mold can form. All of these insects, should they get out of hand can be controlled by approved sprays available at garden centers. With limited numbers of plants, beetles and stink bugs can be controlled by hand picking.

Cutworms can also be a nuisance. (Control by wrapping the tomato plant stem an inch above and an inch below the ground with a wrap of a band of newspaper.) Perhaps the most fearsome of tomato pests is the tomato hornworm, a green, monstrous-looking caterpillar with white stripes, usually several inches long. The best method of dealing with hornworms is removing them by hand.

In general insects may be repelled by using organic gardening methods such as natural sprays made from crushed garlic mixed with water and sprayed directly on the plants.

Harvesting Tomatoes

When a tomato turns bright red it is ready to pluck from the vine. Tomatoes ripen from the inside to the outside. Tomatoes are slow to ripen at temps higher than . In areas where the summers stay very hot, tomatoes can be picked while still pink and brought indoors for further ripening. Once tomatoes are in the pink stage they do not need light in order to ripen. The best course is to store them out of the sunlight at comfortable room temperatures.

Since tomatoes are highly susceptible to frost, even a light early frost will cause devastation to the plant. They can usually be protected from a light frost by draping them with old sheets, plastic, paper bags, or large boxes. If a heavy freeze is imminent, pick all the tomatoes. Green tomatoes that have reached more than 3/4 of their full weight should still ripen. Smaller tomatoes can be pickled. To ripen green tomatoes lay them out on a counter-top and place newspaper over them. The newspaper traps ethylene gas given off by the tomatoes which also helps them to ripen.

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