Tomatoes are the most popular garden vegetables in America.
For many years, however, tomatoes (then called "love apples") were considered poisonous and were grown solely for their ornamental value.
Tomatoes are usually easy to grow and a few plants provide an adequate harvest for most families. The quality of fruit picked in the garden when fully ripe far surpasses anything available on the market, even in season. The tomato plant is a tender, warm-season perennial that is grown as an annual in summer gardens all over the continental United States. Spring and fall freezes limit the outdoor growing season.
Selecting Tomato Varieties
Hundreds of varieties of tomatoes are now available for the home gardener. They range widely in size, shape, color, plant type, disease resistance, and season of maturity. Catalogs, garden centers, and greenhouses offer a large selection of tomato varieties, and choosing the best one or two varieties can be extremely difficult. Evaluate your needs, then choose the varieties best suited to your intended use and method of culture.
Tomato plants fall into one of two types that affect ultimate plant height and cultural requirements.
- Tomatoes are determinate if they eventually form a flower cluster at the terminal growing point, causing the plant to stop growing in height.
- Plants that never set terminal flower clusters, but only lateral ones and continue indefinitely to grow taller are called indeterminate.
Older varieties are almost all indeterminate. These can be counted upon to produce abundant foliage and to ripen flavorful fruit. They may, however, be extremely late in maturing and can become vining behemoths in the garden.
The first determinate varieties developed had real problems with inadequate foliage cover and taste, but they ripened very early. Newer determinates produce better foliage, may grow taller and ripen fruit of similar quality to modern indeterminate varieties. They still tend to ripen their fruit over a shorter period of time, so successive plantings may be desirable with determinates to keep the harvest coming through the entire season.
Determinate vines are easier to control and support during the growing season. Some of the extreme dwarf types are determinate as well as dwarf, producing some truly tiny mature plants.
Reading a plant label: A guide to abbreviations
- F=Fusarium N=nematodes
- T=Tobacco mosaic virus
- AAS=All America Selection
First-Early Red (60 or fewer days to harvest)
These varieties have more compact plant growth than the main-season varieties and sun-burning of the fruit is a problem in hot weather. The main crop varieties are generally far superior for summer-long harvest. First, early varieties are better suited for northern areas, where the growing seasons are shorter and the summers cooler. They have small to medium-sized red fruit and are usually not suitable for pruning.
Medium-Early Red (60 to 69 days)
These varieties are intermediate between the extreme earliness of the first earliest and the sounder plant type and production characteristics of the main crop types. Fruit size is improved, as is quality. The real tomato harvest season begins with the medium early varieties.
Most of the main crop varieties bear medium-sized to large fruit, have adequate foliage cover, and are relatively free from fruit cracking and other deformities. They are suitable for growing on mulch, in wire cages, or on trellises. Many of them can be pruned and trained to stakes. As the name implies, they should make up the bulk of the main crop harvest because they have superior yield, better staying power in the garden, and fruit of high quality.
These varieties are relatively late maturing. The fruits may be extremely large but also can be misshapen, with rough scar tissue ("cat-facing") on the blossom end. When this scar tissue must be cut away, some of the advantage of extra-large size is lost. Large size, though, is seldom about total yield, but more often about the novelty of huge size.
Some of the newer hybrid large types like Supersteak and Beefmaster have fruit with much more consistent shape.
Yellow or Orange
Contrary to popular belief, yellow and orange fruited varieties are not significantly lower in acid content than red tomatoes, and they are equally safe to can or process. They "taste" sweeter than red varieties, because they have a higher sugar content. Current varieties in this classification have much earlier maturity and better plant growth characteristics than older yellows and oranges, which tended to be big, sprawling and late maturing.
These varieties always have maintained a loyal following in certain regions of the country. Pinks traditionally have been similar to yellows with regard to plant type and maturity. Recent breeding work has developed disease-resistant plants with very attractive fruit. For the highest eating quality, some of the older types may still be at the top for flavor.
Other Colors and Types
Although odd colors and bi-colored types have been around for a long time, they have experienced a resurgence in popularity. As these outlets have competed to offer the newest and brightest assortment of produce, some almost-forgotten tomatoes have been "rediscovered."
Red Paste Types
Paste tomatoes are usually used for making catsup, paste, and sauces and for canning whole. Their solid, meaty, low-moisture flesh makes processing these products less complicated. Recently, some of them are becoming trendy for eating fresh. These are usually short plant types that tend to set up a large load of fruit in a short time and then ripen a large proportion of this fruit at once. With tomatoes used fresh, it is usually seen as an advantage to have fruit ripening over an extended season on individual plants, but ripening most of the crop in a short period has been a bonus for paste tomatoes because processing activities are best done in fairly large lots.
These varieties are generally vigorous growing and productive. They vary in size from 1 to 1-1/2 inches in diameter and are usually suitable for pruning. Production per plant is very high, to the point that picking may become tedious. Whole clusters may sometimes be picked at one time to speed the harvest. Splitting seems to be more of a problem with cherries, though newer hybrids have attempted to lessen the problem. These types are usually described as especially sweet and tasty.
These tomatoes are popular for use in containers, hanging baskets, and garden or patio locations where space is limited. Because more people now live where traditional vegetable gardening is not possible, container and patio gardens have become more popular. Their ornamental value is an added benefit and their fruit quality has recently been improved as well. They have fruit in red and some other colors and are not suitable for pruning (except for the new Husky hybrids).
Gardeners interested in growing greenhouse tomatoes should know that specific varieties have been developed for this environment. Some catalogs now routinely list these types, which should be used for the most satisfactory results. Consult catalogs for varieties available.
A particularly large number of heirloom tomato varieties are available today, mainly because tomatoes normally do not cross-pollinate. Seed saved from fruits of non-hybrid varieties produce plants fairly identical to the parent plant. Many of the odder colors and types that have resurfaced lately have their origins in these older, self-saved varieties. The plant type is usually large, sprawling, and late compared to current commercial varieties. Disease resistance may also be suspect. If, however, the gardener wants to try a few truly weird or tasty types, these usually mature some fruits almost anywhere except in the shortest-season areas. Specialty seed houses and exchanges are a source of the widest variety of heirloom tomatoes imaginable.
When to Plant
Buying transplants or starting seeds indoor early, gets tomatoes off to the best start in the garden when warm weather finally arrives and it saves several weeks in growing time.
- Some gardeners transplant their tomatoes soon after the soil is prepared for spring gardening when there is a high risk of damage from freezing.
- Be prepared to cover early planted tomatoes overnight to protect them from frost.
- For best results with very early plantings, consider black plastic mulch and floating row covers for heat accumulation and frost protection.
- For best results with minimal risk, plant when the soil is warm, soon after the frost-free date for your area.
- While everyone wants that first tomato, be mindful that setting a tomato plant out too early can slow its growth to a standstill. It may take up to two weeks for a tomato plant exposed to cold night temperatures to resume normal growth.
For fall harvest and early winter storage of tomatoes, late plantings may be made from late spring until mid-summer, depending on the length of the growing season.
- These plantings have the advantage of increased vigor and freedom from early diseases, and they often produce better quality tomatoes than later pickings from early spring plantings.
- Time late plantings for maximal yield before killing freezes in your area (up to 100 days from transplanting for most varieties).
Spacing & Depth
The space required depends upon the growth pattern of the variety and method of culture.
- Space dwarf plants 12 inches apart in the row, staked plants 15 to 24 inches apart, and trellised 24 to 36 inches apart.
- Some particularly vigorous indeterminate varieties may need 4 feet between plants and 5 to 6 feet between rows to allow comfortable harvest room.
- Apply starter fertilizer when transplanting.
- Hoe or cultivate shallowly to keep down weeds without damaging roots.
- Mulching is recommended, especially for gardeners who wish to maintain their plants for full-season harvest.
- Black plastic or organic materials are suitable for mulching.
- Delay application of organic materials until after the soil has warmed completely in early summer so that growth is not slowed by cool soil temperatures early in the season.
Water the plants thoroughly and regularly during prolonged dry periods.
- Plants confined in containers may need daily or even more frequent watering.
- Side-dress nitrogen fertilizer (ammonium nitrate) at the rate of one pound per 100 feet of row (equivalent to 1 tablespoon per plant) after the first tomatoes have grown to the size of golf balls. (If ammonium nitrate is not available, use 3 pounds of 10-10-10 fertilizer.)
- Make two more applications 3 and 6 weeks later.
- If the weather is dry following these applications, water the plants thoroughly.
- Do not get fertilizer on the leaves.
Many gardeners train their tomato plants to stakes, trellises, or cages with great success. Not all varieties, however, are equally suitable for staking and pruning.
Tomato cages may be made from concrete-reinforcing wire, woven-wire stock fencing, or various wooden designs.
- Choose wire or wooden designs that have holes large enough to allow fruit to be picked and removed without bruising. The short, small, narrow type often sold at garden centers is all but useless for anything but the smallest of the dwarf types.
- Most modern determinate tomatoes easily grow 3 to 4 feet tall and indeterminates continue to get taller until frozen in the fall, easily reaching at least 6 feet in height.
- Use cages that match in height the variety to be caged and firmly anchor them to the ground with stakes or steel posts to keep the fruit-laden plants from uprooting themselves in late summer windstorms.
Trellis-weave systems have recently been developed for commercial operations and can work just as well in a garden planting.
- Tall stakes are securely driven into the tomato row about every two or three plants in the row. Make sure the stakes are tall enough to accommodate the growth of your tomato varieties and make sure they are driven very securely into the ground to prevent wind damage. (The woven rows of tomatoes can catch much wind.)
- As the tomatoes grow upward, strings are attached to the end posts and woven back and forth between the supports, holding the tops of the plants up and off the ground.
- This operation is repeated about as often as the tomatoes grow another 6 inches until the plants reach maturity.
- The fruit is held off the ground as with staked or caged plants, but the foliage cover is better than with staked plants, and the fruit is more accessible than with cages.
Tomato hornworms are large (2 to 3 inches long when fully grown), green caterpillars with white stripes on their body. A horn protrudes from the top rear end of the worm.
- Tomato hornworms feed on the leaves and fruit. Several worms on one plant can quickly defoliate it and ruin developing fruit. Because their green coloring so closely resembles tomato foliage and stems, they are difficult to see.
- You can scout for hornworms at night using a handheld blacklight. When the blacklight shines on a tomato hornworm it glows in the dark.
- Handpick in cooler parts of the day or use suggested biological insecticides.
- If you see hornworms with small, white cocoons protruding, leave them alone. These structures are the pupae of parasitic insects that help control the hornworm population and the individual wearing them is already doomed.
Verticillium and fusarium wilts are soilborne diseases that cause yellowing of the leaves, wilting and premature death of plants. These diseases persist in gardens where susceptible plants are grown. Once they build up, the only practical control is the use of resistant (VF) varieties.
Early blight is characterized by dead brown spots that usually start on the lower leaves and spread up the plant. Upon close inspection, you can see concentric rings within the spots. Although early blight is most severe on the leaves, it sometimes occurs on the stems and can cause severe defoliation. Certain varieties (Roma and Supersonic) are more tolerant of early blight than others.
Septoria leafspot is characterized by numerous small black spots on the leaves. The centers of these spots later turn white and tiny black dots appear in the white centers. The disease starts on the bottom leaves and may become severe in wet weather.
Blossom-end rot is a dry, leathery brown rot of the blossom end of the fruit that is common in some seasons on tomatoes. It is caused by the combination of a localized calcium deficiency in the developing fruit and wide fluctuations of soil moisture. The problem is especially bad in hot weather.
- Soil applications of calcium seldom help, though foliar calcium sprays may minimize the occurrence of the problem.
- Make sure the formulation is designed for foliar application or severe damage could result.
- Pruning causes stress to the plants that may increase the incidence of blossom-end rot.
- Some tomato varieties are much more susceptible to this condition than others.
- Mulching and uniform watering help to prevent blossom-end rot.
Once the blackened ends appear, affected fruits cannot be saved. They are best removed and destroyed so that healthy fruit setting later can develop more quickly.
Poor color and sunscald occur when high temperatures slow the development of full red color in tomatoes exposed directly to the hot sun.
- Sunscald occurs as a large, whitish area on the fruit during hot, dry weather. It becomes a problem when foliage has been lost through other diseases such as early blight or on early varieties that normally have poor foliage cover as the fruit ripens.
Tomatoes should be firm and fully colored. They are of highest quality when they ripen on healthy vines and daily summer temperatures average about 75°F.
- When temperatures are high (air temperature of 90°F or more), the softening process is accelerated and color development is slowed reducing quality.
- For this reason, during hot summer weather, pick your tomatoes every day or two, harvest the fruits when color has started to develop and ripen them further indoors (at 70 to 75°F).
- On the day before a killing freeze is expected, harvest all green mature fruit that is desired for later use in the fall.
- Wrap the tomatoes individually in paper and store at 60 to 65°F. They continue to ripen slowly over the next several weeks.
- Whole plants may be uprooted and hung in sheltered locations, where fruit continues to ripen.
Selection & Storage
Tomatoes are a favorite among small plot gardeners and nothing tastes better than one that is truly vine-ripened. Although tomatoes are available year-round, vine-ripened tomatoes are only available during the growing season.
Dozens of varieties of tomatoes are available in seed catalogs and as transplants. They come in a wide range of sizes, colors, and shapes. A single tomato plant will grow well in a large flowerpot or bucket. The point is if you do not plant anything else, plant a tomato and eat fresh tomatoes often. Tomatoes generally fall into three categories, slicing round tomatoes, plum tomatoes, and small cherry tomatoes. Variety selection should be suited to how you will use them.
- Slicing tomatoes are large round varieties, which hold more juice and seeds. They are perfect for eating raw in a wide variety of ways. Plum tomatoes are meaty, eggplant-shaped, and may be red or yellow. They are excellent for sauce making, canning, and pizzas. Small cherry-type tomatoes are generally served whole, although they can be cut in half and sautéed in any dish. They contain a great deal of seeds and juice.
- Fresh ripe tomatoes should not be stored in the refrigerator. Unfortunately, refrigeration renders them tasteless and turns the flesh to mealy mush. Flavor and texture begin to deteriorate when the temperature drops below 54°F. Temperatures above 80°F cause tomatoes to spoil quickly. Store tomatoes at room temperature for 2 to 3 days, away from direct sunlight until ready to use (sunlight hastens ripening).
- Refrigeration also slows ripening of tomatoes. Refrigerate only extra-ripe tomatoes you want to keep from ripening any further. To reverse some of the damage, bring chilled tomatoes to room temperature before serving raw or simply add to cooked preparations.
- To ripen tomatoes, place them in a paper bag, stem end up. Punch several holes all around the bag and fold the top over. The bag will help to keep some of the natural ethylene gas in place, which aids in the ripening process. Depending on how under-ripe they are, tomatoes may take one to five days to ripen. Check progress daily.
Questions & Answers
Q. What causes the lower leaves of my tomato plants to roll up?
A. Leaf roll (curling of the leaflets) is a physiological condition that occurs most commonly when plants are trained and pruned. It should not affect fruiting or quality.
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 with drying hot winds), tomatoes do not set and flowers drop. The problem usually disappears as the weather improves.
Q. What can I do to prevent my tomatoes from cracking?
A. Cracking varies with the variety. Many of the newer varieties are resistant to cracking. Severe pruning increases cracking. Keep soil moisture uniform as the tomatoes develop and plant resistant varieties to minimize this problem.
Q. What causes small, irregular, cloudy white spots just under the skin of my tomatoes?
A. These spots on green or ripe fruits are caused by the feeding of stink bugs.
Q. What causes the young leaves of my plants to become pointed and irregular in shape? I notice some twisting of the leaves and stems after spraying the plants for the first time.
A. Judging from the description, it seems likely that your tomato plants 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. Drift from herbicides originating 1/2 mile or more away also can injure your tomato plants. For this reason, use extreme caution when applying lawn care chemicals near vegetable or fruit plantings.
Q. What is a tree tomato?
A. The treelike plant sold as a "tree tomato," is a different species from garden tomatoes. It is a woody tree that grows 8 feet or taller and bears after 2 years. The tree tomato is a tropical plant and does not overwinter outside anywhere the temperature drops below freezing. The fruits are small (1 to 2 inches in diameter) and are used primarily in stews or preserves rather than in salads. Some of the common, vigorous, indeterminate garden tomato varieties that are suitable for training and pruning (such as Ponderosa) are also sold as climbing or "tree tomatoes" by some seed stores.
Q. What is a "potomato?
A. Although both potato and tomato plants can be integrated, the "potomato" (sometimes called "topato") commonly advertised is simply a tomato seed inserted into a potato tuber and planted together, producing both a tomato plant and a potato plant in the same hill. The results are not likely to be particularly successful.
Q. My grandpa grew a heart-shaped, dark pink tomato that was thick and meaty, yet juicy with great flavor. Grandpa's gone and I can't find a source for the seed. What can I do?
A. Fortunately, there are a number of seed exchanges like Seed Savers Exchange, which have been finding and rescuing old varieties. Older and heirloom varieties are also available from conventional seed sources these days. Perhaps, by doing some homework and contacting one or several of these sources, you can find a variety that is exactly (or very nearly) like those you remember from your grandfather's garden. As a guess, the variety sounds like one called Oxheart, which used to be fairly common and has recently become rare.
Preparing Tomatoes for Exhibition
Former Extension specialist Jim Schmidt demonstrates how to properly prepare tomatoes for exhibition.