Tomatoes are either determinate or indeterminate. The determinate types are gaining in popularity in home gardens. Determinate tomatoes are referred to as 'self-topping' or low growing types. They will usually grow to a height of 3 to 4 feet, depending on the variety. The terminal bud then forms a flower, and the plan does not grow any taller. As a result, they can usually be staked with 4- or 5-foot stakes or cages. Determinate varieties will bear fruit primarily over a four- to five-week period, then fruit production decreased considerably.
Indeterminate types have a different growth habit than determinate types. They are not self-toppers and usually produce fruit throughout the entire season unless they are killed by diseases or insects. They require 5- to 6-foot stakes to provide good support. Indeterminate fruit is usually softer and has more gel and thinner walls than determinate types.
Determinate varieties that are increasing in availability are Floriamerica, Royal Flush, Pik Red, Celebrity, Liberty, Revolution, Mountain Pride, Floradade, Sunny and Duke. Indeterminate varieties that are favored by home gardeners are Better Boy, Big Seven, Jet Star, Fantastic, Bradley, Traveler, Lemon Boy and Sunray.
The first step in growing tomatoes is to prepare the soil. It needs to be fairly fine, but not dust. The soil should be turned in time to allow any undecayed plant residue to decay fully before planting. In warm temperatures, this may require four to six weeks for full decay. When the tomato growing area has been tilled, apply fertilizer and work into the soil before planting. A good rate to apply in lieu of a soil test is two to three pounds of a common fertilizer, such as 6-12-12, per 100 square feet of space. The soil pH should be 6.1 or above with adequate calcium levels to prevent blossom end rot.
Blossom-end-rot is a leather-like decay of the blossom end of the fruit. It is reduced by maintaining adequate lime (calcium) and moisture levels and by avoiding excessive application of fertilizer.
Good yields are possible only when a grower starts with high quality plants. Tomato plants must have a well developed root system that has been kept moist. Normally, tomatoes that have been grown in containers grow better after they have been set in the garden than bare-root plants. Container grown plants will usually produce earlier yields than bare root plants. They have usually been grown with root systems that have had less stress, and their livability is normally higher than with bare-root plants.
When buying tomato plants, choose plants that are about as wide as they are tall. Plants this size will be seven to eight weeks of age. Plants at this age will respond well and produce good yields of fruit. If you are purchasing plants for early spring, they should be conditioned or hardened to withstand adverse spring weather. If they have been conditioned, veins on the underside of the leaf will have a slight purple color. Conditioning can be done by lowering the temperature, reducing the frequency of watering and reducing fertilizer. Temperature can be reduced by moving plants outside during the day and inside at night. This should begin about two weeks before plants are to be transplanted to the garden.
Avoid purchasing plants that have wilted excessively, have spots on the foliage, have foliage that is excessively yellow or which have not been well maintained. If possible, purchase varieties with the letters VFN after their name. This indicates that they have resistance to verticillium and fusarium wilt and to nematodes.
It is best not to plant tomatoes in the same location in the garden two consecutive years. If possible, rotate plants around the garden so they are not planted in the same location more than once every three years. This does not eliminate, but will help prevent, diseases from building up so rapidly in the soil.
When tomatoes are 6 to 8 inches tall, they should be planted deep enough to completely cover the root ball. Planting can be done after the last spring frost through June 25 if desired. If plants have been grown in fibrous containers, the top of the container must be completely covered with soil. The distance between plants in the row depends upon the type of tomatoes being grown and the severity of pruning or succoring that is intended. Succoring consists of removing growth in the leaf axis. Determinate varieties are not as tall growing as indeterminates and can normally be spaced closer in the row. If succoring is not intended, plants will need to be spaced further apart than if they are to be succored. The in-row spacing varies from 18 inches to 24 inches between plants. Between-row spacings can vary from 4 feet to a width suitable for use with the cultivation equipment available.
If tall leggy plants are to be planted, it is advisable to either lay a portion of the plant horizontal or plant it 6 to 8 inches deep. This allows the plant to develop a root system along all of the buried stem.
Organic mulches, such as straw, leaves, grass clippings or compost, can be applied after plants are set. Mulches vide weed control, uniform moisture levels, reduce certain disease problems and improve fruit quality. Organic mulches should not be applied until the soil temperature has warmed up.
Black plastic can be used to maintain uniform moisture, control weeds, enhance earliness and improve fruit quality. If plastic is used, lay 4-foot wide strips in the row area and seal the edges with about 6 inches of soil about two weeks before the planned transplanting date. Arrange to place plants prior to planting by making slits in the plastic at the desired places.
The best quality tomatoes are grown on supports. It requires less space to produce the same quantity of edible products with support than unsupported tomatoes. Tomatoes are normally supported with stakes or cages. If stakes are used, each stake is about 4 feet tall for determinate types or 6 feet for indeterminate types. Stakes can be provided for each plant and tied loosely stake can be placed between each two plants and supports provided by the 'Florida Weave' technique.
String is tightly stretched horizontally along both sides of the stakes at the same height with plants held between the string layers. String layers are repeated every 8 to 10 inches vertically as the plant grows. When stakes are strong and well anchored, this system provides sufficient support to keep plants off the ground. Usually, two plants are set between stakes. Tomatoes are often succored with this system.
When cages are used for support, the cage must be of strong materials such as reinforced concrete wire. It should be well anchored to support the weight of the plants and fruit. The cage should have sufficient opening to allow removal of ripe fruit. A 6-foot length of wire will form a cage about 21 inches in diameter. Unsuccored tomatoes are allowed to grow in the cage. Yields per plant are usually higher in a cage than when supported by stakes.
Sidedressings applied at the right time and at the correct rate can greatly enhance the production of tomatoes. Sidedressings are applications of fertilizer along the plants at some stage of growth. They are started when fruit on the first cluster is about the size of a half-dollar and repeated every four weeks through harvest. If they are applied prior to this time, it is very likely that blooms will be blasted and fruit set will be eliminated or reduced. Ammonium nitrate is the most common nitrogen source. Apply one tablespoon in a circle around the plant at each sidedressing about 12 inches from the plant.
For best tomato growth, keep the soil in the root zone moist enough to prevent wilting of tomatoes. This is best done by applying 1/2 to 3/4 inch of water twice a week to the root zone during periods of dry weather. If possible, use trickle irrigation; less foliage diseases occur with trickle than sprinkler irrigation. If sprinkler irrigation is used, apply as late in the afternoon as possible but early enough to allow foliage to dry before nightfall.
Alvin D. Rutledge, Professor Emeritus,
Plant & Soil Science
The University of Tennessee, Knoxville