Tomatoes can be planted in your garden if night temperatures are averaging warmer than 55ºF. One key to tomato success is simply to remember that tomato blossoms don’t set fruit when the night temperature is below 55ºF or above 70ºF (13-21ºC).
It’s best to choose tomato varieties suited to your climate: varieties for cool weather, hot and humid weather, or hot and dry weather. Check with tomato growing friends or a nearby garden center to see which varieties are favorites in your area. You can also ask the growers at the farmers’ market nearest to you.
Once you choose your tomatoes, the growing part is straight forward. Here are a few guidelines:
Site. Plant tomatoes in full sun. In cool regions, plant tomatoes near a wall or the side of a house or building that faces west or south. The wall will soak up the day’s heat and release it at night keeping tomatoes warm.
Container growing. Tomatoes can be grown in containers indoors year-round. Minimum container depth should be 12–18 inches (31-45 cm) deep and just as wide Indoors use ultraviolet “grow lights” to promote flowering and fruiting—tomatoes require a minimum of 6 equivalent full-sun hours per day. For container plants, install a cage at the time of planting to support the plants’ foliage and fruits.
Soil. Tomatoes prefer light, loose, fertile, well-drained soil with plenty of organic matte or compost added. Add a handful of bone meal to each planting hole. If you live in a cool region, warm the soil by placing black plastic on the bed a few weeks before planting.
Sowing seed. Sow tomato seed ½ inch (13 mm) deep and 18–48 inches (45–122 cm) apart, thinning successful plants to 36–42 inches (90–107 cm) apart.
Selecting garden center seedlings. Select plants 6–8 weeks old, usually in a 4-inch (10 cm) pot. Check bottom of pot to make sure roots are not growing through and plant is not root bound. The best seedlings are short bushy plants with dark foliage and no flowers.
Transplant seedlings. Transplant tomato seedlings 12–24 inches (30–60 cm) apart for determinate or bush varieties and 24–36 inches (60–90 cm) apart for indeterminate or climbing varieties. Place tomatoes into a 6-inch (15 cm) hole, allowing 4 inches (10 cm) of plant to remain above the soil. Clip off leaves below soil line. The plant will form added roots on the buried stem.
Planting time in short-season climates. If you live in a region where the growing season is short, choose extra-hardy, early-maturing tomato varieties.
Watering. Keep the soil moist but not wet; maintain even moisture throughout growth period. Water heavily enough to reach the plant’s deepest roots, about 1–2 inches (2.5–5 cm) of water every week.
Feeding. Tomatoes require a moderate amount of nitrogen and ample amounts of phosphorus and potassium. Abundant soil phosphorus is important for early high yields. Too much nitrogen will encourage leaf growth, but not flowers and fruit or soft fruit susceptible to rot. Once the plants is well established and in full blossom, feed your tomatoes with a weak compost tea or fish emulsion every 2 weeks from the first blossoms set until the end of harvest.
Staking. Bush tomato varieties can be grown without support although cages may be used. Climbing tomato varieties should be staked, trellised, or caged, and pruned for best results. Train indeterminate tomatoes using a 2-by-2-inch (5 cm) 6-foot-long (1.8 m) stake, a wire tomato cage or cylinder with opening large enough to put your hand through. Set the support in place at planting time. Anchor cages to a pair of 4-foot (1.2 m) stakes driven into the ground before planting. Use soft ties to train the plant to a stake, or train branches through the cage as the plant grows. Tie the main stem every foot or so with soft twine or horticultural tape.
Pruning and pinching. Indeterminate vines should be pruned so that only one or two main stems develop. Pinch off suckers that grow between the main stem and the branches. (Suckers are non-flowering shoots that grow in the angle between the main stem and leaf stalks.) Pruning allows nutrients to be used for fruit development. Pinch out the growing tips when the plant reaches the top of its support.
Pests. Protect young tomato plants from cutworms with cardboard, plastic, or metal collars. Handpick tomato hornworms or use Bacillus thuringiensis (Bt).
Diseases. Tomatoes are subject to a variety of plant diseases, both viral and fungal. Plant geneticists have developed disease-resistant varieties, identified by the letter “V” (verticillium wilt), “F” (fusarium wilt), “N” (nematodes, a microorganism that causes cankers on the roots), and “T” (tobacco mosaic virus—tomatoes are a relative of the tobacco plant, and subject to viral diseases of that plant species). Select resistant varieties; use young, healthy transplants.
Harvest. Harvest tomatoes in late summer 50 to 90 frost free days after planting. Pick the fruit when it is evenly colored but still firm. Support the vine in one hand and gently pull the fruit to prevent damage to the plant. A month before the first expected frost, start plucking new flowers off the plants. This will direct the plant’s energy into ripening tomatoes already on the vine.
Varieties. There are more than 1,000 tomato varieties, but there are just three major tomato categories based on use: cherry or miniature, cooking, and slicing and eating:
• Cherry or miniature: smallest ranging in size from ¾–1½ inches (1.9–3.8 cm) in diameter and in hues of red, yellow, and zebra-stripe green. Use in salads or for snacking. Well known varieties include: ‘Sweet 100 Plus’, ‘Sun Gold’, ‘Matt’s Wild Cherry’.
• Cooking: usually oblong or pear shaped, with meatier, less juicy flesh than the eating varieties; sweeter flavor; generally ripen at the same time providing quantities for canning and sauces. Well known varieties include: ‘Juliet’, ‘Tuscany’, ‘Milano’, ‘Amish Paste’, and ‘San Remo’.
• Slicing and eating: generally the largest, juiciest, most flavorful tomatoes. They come in both early-season and longer-developing varieties; those with longer growth periods have enhanced taste and texture. Well known varieties include: ‘Celebrity’, ‘Big Beef’, ‘Big Boy’, and ‘Better Boy’.