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How to Grow Tomatoes
Tomatoes (Lycopersicon esculentum) are valuable garden plants in that
they require relatively little space for large production. Each plant,
properly cared for, yields 10 to 15 pounds or more of fruit.
PLANTING
Tomatoes are warm-season plants that grow best at temperatures of 70 to
80 F during the day and 60 to 70 F during the night.
Tomato plants may be started indoors from seed, or transplants may be
purchased from a reputable garden center. If starting your own plants, use a
light soil mix and give the plants plenty of light. Tall, spindly
transplants are usually caused by low light levels in the home. Unless you
have a sunny, south-facing window, supplemental light will probably be
necessary. The seeds are sown six to eight weeks before the last frost date
in your area. A week before transplanting time, harden-off indoor-grown
plants by exposing them to an increasing number of hours outdoors each day.
When you are ready to put homegrown or purchased plants into the ground,
select stocky transplants about 6 to 10 inches tall. Set tomato transplants
in the ground, covering the stems so that only two or three sets of true
leaves are exposed. If transplants become "leggy," horizontal planting of
tomato plants is an effective way to make plants stronger. Roots will form
along the buried portion of the stem, giving better growth and less chance
of plant injury from an excessively weak stem. Do not remove the containers
if they are peat or paper pots, but open or tear off one side to allow roots
to become free. If non-biodegradable containers are used, knock the plants
out of the pots and loosen the roots somewhat. Press the soil firmly around
the transplants so that a slight depression is formed for holding water.
Pour about 1 pint of starter solution (2 tablespoons of 5-10-10 or 5-10-5
fertilizer per gallon of water) around each plant.
If plants are to be staked or trellised, space them 24 inches apart in
rows 3 feet apart. Although it requires more initial work, staking makes
caring for tomatoes easier than letting them sprawl. Since they are off the
ground, fruit rots are reduced, spraying is easier and may be required less,
and harvesting is much less work. Use wooden stakes 6 feet tall and 1 ½ or 2
inches wide. Drive them 1 foot into the soil about 4 to 6 inches from the
plant soon after transplanting. Attach heavy twine or strips of cloth to the
stakes every 10 inches.
Prune staked tomatoes to one or two main stems. At the junction of each
leaf and the first main stem a new shoot will develop. If plants are trained
to two stems, remove all other shoots, called suckers, weekly to maintain
these two main stems. Pinch shoots off with your fingers.
Growing tomatoes in wire cages is a popular method among gardeners
because of its simplicity. Cage-growing allows the tomato plant to grow in
its natural manner but keeps the fruit and leaves off the ground. Using wire
cages requires initial expenditure, but they will last many years. Be sure
to get fencing with at least 6-inch spacing between the wires so that you
can get your hand inside to harvest the tomatoes.
If tomato plants in wire cages are pruned at all, once is enough. Prune
to three or four main stems. Wire-cage tomatoes develop a heavy foliage
cover, reducing sunscald on fruits. Caged plants are less prone to the
spread of disease from plant handling, since they do not have open wounds
and are handled less frequently than staked plants. However, it helps to
space the plants somewhat further apart (3 feet) to allow good air
circulation between plants. Humidity is higher because of the foliage
density, and diseases, such as late blight, spread rapidly in humid
situations.
TYPES
The varieties of tomato plants available may seem overwhelming, but they
can be summed up by several major types:
- Midget, patio or dwarf tomato varieties have very
compact vines and grow well in hanging baskets or other containers. The
tomatoes produced may be, but are not necessarily, the cherry-type (1-inch
diameter or less).
- Cherry tomatoes have small fruits often used in
salads. Plants of cherry tomatoes range from dwarf (Tiny Tim) to 7-footers
(Sweet 100).
- Compact or determinate tomato plants grow to a
certain size, set fruit and then decline. Most of the early-ripening
tomato varieties are determinate and will not produce tomatoes throughout
a South Carolina summer.
- Beefsteak types are large-fruited. These are
usually late to ripen.
- Paste tomatoes have small pear-shaped fruits with
very meaty interiors and few seeds. They are a favorite for canning.
- Some tomatoes are orange or yellow. Sometimes the
only way to get these is by growing your own.
- Winter storage tomatoes are set out later in the
season than most tomatoes and fruits are harvested partially ripe. If
properly stored, they will stay fresh for 12 weeks or more. While the
flavor does not equal that of summer vine-ripened tomatoes, many people
prefer them to grocery store tomatoes in winter.
RECOMMENDED CULTIVARS
The following tomato cultivars are recommended for South Carolina
gardens. Most cultivars are indeterminate, except for Celebrity and Small
Fry.
- Better Boy, Better Bush Improved, Big Beef, Celebrity, Early Girl,
Park’s Whopper, Terrific
- Cherry Type: Juliet, Small Fry, Super Sweet 100, Sweet Million
- Plum Type: Viva Italia
- Trellis: Tropic
Always choose varieties with disease resistance. Fusarium wilt is a
common disease that can destroy a whole tomato crop. Many varieties are
resistant to this disease. This is indicated by the letters VF after the
cultivar name. VFN means the plants are resistant to Verticillium, Fusarium
and nematodes; VFNT adds tobacco mosaic virus to the list.
FERTILIZING
A soil test is always the best method for determining the fertilization
needs of a crop. The desired soil pH for tomatoes is between 5.8 and 6.5.
Tomatoes are heavy feeders. Use a starter solution for transplants.
Sidedress when the first fruits are about the size of quarters, using 1 ½
ounces tomato fertilizer per 10 feet of row. Sidedress again two weeks after
the first ripe tomato with a balanced fertilizer such as 5-10-5, and repeat
this one month later. Never feed tomatoes with a fertilizer that contains
chlorides. Always check the label for the "derived from" label for potassium
chloride, muriate of potash or calcium chloride. Tomatoes are very sensitive
to chlorides and it should be avoided if possible.
CULTURAL PRACTICES
Blossom-end rot can be a serious problem with tomatoes. The main symptom
is a dark-colored dry rot of the blossom ends of the fruit. It occurs when
there are extremes in soil moisture, which cause calcium deficiency in the
fruit. When rain or irrigation follows a dry spell, the roots cannot take up
calcium fast enough to keep up with the rapid fruit growth. Blossom-end rot
also occurs if the delicate feeder roots are damaged during transplanting or
by deep cultivation near the plants.
The following measures will help prevent blossom-end rot:
- Test the soil and maintain a pH between 6 and 6.5 and an adequate
calcium level by liming or applying gypsum.
- Mulch with 2 to 3 inches of materials such as grass clippings, pine
straw and leaves. Mulching prevents rapid soil drying and allows roots to
take up available calcium efficiently.
- Do not overfertilize plants with nitrogen or potash. Excessive amounts
of these nutrients depress the uptake of calcium.
- Keep moisture levels fairly uniform by regular watering and by
maintaining a mulch layer around the base of the plants. Water plants
during extended dry periods. Tomatoes need 1 to 1 ½ inches of water per
week.
Add organic matter to the soil. This will help "loosen" clay soils and
will improve the water-holding capacity of sandy soils. In either soil,
organic matter will increase plant uptake of water and calcium.
HARVEST AND STORAGE
It takes 55 to 105 days to maturity depending on the tomato variety. Pick
fruit when it is fully vine-ripened but still firm; most varieties are dark
red. Picked tomatoes should be placed in the shade. Light isn’t necessary
for ripening immature tomatoes. Some green tomatoes may be picked before the
first killing frost and stored in a cool (55 F), moist (90-percent relative
humidity) place. Do not store green tomatoes in the refrigerator since red
color will not develop at less than 50 F. When necessary, ripen fruits at 70
F. Green tomatoes can be stored at 50 to 70 F for one to three weeks. Ripe
tomatoes should be stored at 45 to 50 F for four to seven days.
COMMON PROBLEMS
Besides blossom-end rot, the following problems are common:
- Leaf roll: This is a physiological condition caused by excess water.
- Growth cracks: Tomatoes crack when environmental conditions (drought
followed by heavy rain or watering) encourage rapid growth during ripening
of the fruit.
- Sunscald: This occurs when tomatoes are exposed to the direct rays of
the sun during hot weather.
- Poor fruit set: This occurs for several reasons, such as extreme
temperatures, dry soil, too much shade and excessive nitrogen.
- Tomato blossoms are very sensitive to temperature. At temperatures of
55 to 60 F, pollination can be severely impaired and very few fruits will
form. Temperatures of 90 to 95 F are also very unfavorable for
pollination.
- Catfacing: This is a disorder caused by cold, wet temperatures during
fruit set. The fruit is extremely malformed and scarred.
Originally prepared by Marjan Kluepfel, HGIC Information Specialist, and
Robert J. Dufault, Professor of Horticulture at Coastal REC, Clemson
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