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 set plants 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.
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 frost in your area (up to 100 days from transplanting for most varieties).
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 retarded 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.
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 retarded, 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.