Success in growing tomatoes can be attributed to a few proven techniques. Start by choosing a variety that has been a proven performer. They are often found in garden centers or farm stands or by talking with experienced gardeners. In recent years there has been a lot of interest in heirloom varieties. Heirloom varieties, if grown on their own rootstock, are not likely to be resistant to verticillium wilt or fusarium wilt, common problems in growing tomatoes. Grafting is an old technique that involves matching the top part of one variety onto the bottom part of another variety. More recently this technique is being used to allow gardeners to the benefit of harvesting heirloom varieties of tomato fruits while having the benefits of disease resistance and higher yields of a hybrid. The rootstock is chosen for its disease-resistance, vigorous growth, and high fruit yield. The scion is selected for the taste of the fruit. Many heirloom varieties that have large fruits, but may lack disease-resistance or productivity are now being grown on grafted rootstock. Grafting involves splicing the fruit-producing shoot called the ‘scion’ of a desirable cultivar onto the disease resistant rootstock from of another cultivar.
The VF designation, something to look for when purchasing tomato plants, means the tomato variety is resistance to verticillium wilt and/or fusarium wilt. These two problems often originate from your garden soil and can destroy a crop before you harvest a single tomato. In the end, it is best to experiment with several varieties in order to find the ideal tomato for your taste buds and growing conditions.
Use the best soil available to grow your tomato crop. In poor, sandy soils, adding peatmoss or other forms of organic matter in the top 6 to 9 inches of soil is an important step.
Lime and fertilizer should be added according to soil test recommendations. If no soil test has been taken, 3/4 cup of lime should be applied to each plant, along with fertilizer. The rate of fertilizer depends entirely on the type of fertilizer being used. Follow the recommendation on the fertilizer container. Lime will help reduce nutrient imbalances by allowing the nutrients that are present in the soil to be taken up by the plants. This is particularly true for calcium and can help control blossom end rot that occurs so frequently on tomatoes.
Tomato plants should be spaced 1 1/2 to 2 ft apart in the row with 3 to 4 ft between rows. The planting hole should be deep enough to allow the entire root ball to be covered with one inch of soil. If the transplant is tall and leggy at time of planting, the trench planting method should be used. To trench plant a tomato plant, dig a horizontal trench rather than a hole for each plant. Next, remove all of the leaves from the plant except the top leaf cluster (4 to 5 leaves). Then lay the plant on its side in the trench and cover the root system and bare stem up to the top leaf cluster with 2 to 3 inches of soil. Firm the soil over the plant. Be sure not to press the soil too firmly around the stem where it comes out of the soil, as the stem may break.
Tomato plants should be staked or caged shortly after planting. A common 6-ft tomato stake may be purchased from many garden centers. The stake should be driven in the soil about one ft deep, 3 to 5 inches from the plant. Be sure to avoid driving the stake on the root side of plants that have been trench planted. Trench planted tomatoes should be staked immediately after planting while the location of the buried stem is fresh in your mind. Use a strip of cloth, nylon stocking, or heavy string to tie the plant to the stake.
Sidedress tomato plants with 2 to 3 Tbsp. per plant of a complete fertilizer such as 8-8-8 or 10-10-10 after the plants have started to set fruit and 4 to 6 weeks thereafter throughout the growing season. Keep the fertilizer 4 to 6 inches from the plant's stem to avoid fertilizer burn. Many successful gardeners use liquid/water soluble fertilizers, but whether you use granular or water soluble fertilizer, do not over do it. Too much fertilizer will result in lots of leaves and healthy looking plants, but fewer tomatoes.
For soil testing, the UMass Soil and Plant Nutrient Testing Laboratory is located on the Amherst campus of the University of Massachusetts. Information on submitting a soil sample for testing and forms
It is important to make sure the tomatoes receive sufficient water during the season. The soil should be soaked 6 to 8 inches deep at 7-day intervals. Mulches such as straw or composted leaves around the tomato plants will prove to be a real asset in conserving soil moisture during July and August.
Finally, have a prepared plan for dealing with the various insect and disease problems. Frequent observation of tomato plants for pest damage is the only way to stay ahead of nature.