It depends on whom you ask. A tomato fits the botanist’s definition of a fruit: a seed-bearing structure that develops from a flower. But to a chef who thinks in culinary terms, it’s a vegetable. Among the other crops that share this dual identity are squash, eggplant, peppers, and cucumbers.
Gardeners who purchase tomato transplants are limited to whatever their local garden center happens to be selling. Start your own plants from seed, however, and the entire world of tomatoes is available to you, from cherished heirlooms to the latest hybrids. You don’t need a greenhouse to do it; up to four flats of seedlings will fit under a 4-foot shop light with four fluorescent tubes. Start the seedlings 6 to 8 weeks before you plan to move them to the garden. Warmth—around 78degrees F—facilitates germination, but from then on, reduce the temperature to about 68 degrees F to encourage stocky growth.
Planted too early in the growing season, tomatoes will simply sit and wait for warmer weather before they grow or set fruits. So if you want to harvest the earliest tomatoes on your block, find ways to keep them warm.
About a week before setting out transplants, spread black paper or plastic mulch over the ground to soak up solar energy and increase the soil temperature.
Choose varieties that mature in fewer than 60 days, such as ‘Early Girl’. (Keep in mind, however, that early-maturing varieties don’t win contests for flavor.) Cherries and other small-fruited tomatoes tend to ripen more quickly than beefsteaks.
Once planted in the garden, protect the seedlings on cold nights and windy days with cloches or hotcap covers. Or invest in Wallo’Waters, water-filled devices that surround plants with passive-solar warmth.
Most varieties of tomatoes quickly branch into a thicket of stems if no attempt is made to control their growth. “Suckers” emerge at the spot where a tomato leaf attaches to the stem, and as it grows, each sucker becomes another stem. Removing some or all of these suckers helps the plants stay upright, maintains the air circulation they need for good health, and improves fruit quality. Tomatoes trained onto stakes are best pruned to a single stem by removing all suckers. Caged tomatoes can be allowed to develop one or two suckers in addition to the main stem. Make a habit of clipping off unwanted suckers every few days.
In 1986, Gordon Graham of Edmund, Oklahoma, harvested a ‘Delicious’ beefsteak tomato that weighed 7 pounds 12 ounces, setting a record that has not been duplicated since.
Tomato varieties are divided into two categories based on how they grow.
Most varieties—heirlooms included—are tall, lanky indeterminates, which grow and set fruits continually (or until struck down by frost). Indeterminates have long harvest seasons and, usually, the best-flavored fruits.
Determinate varieties, on the other hand, are more compact. Because determinate plants tend to set their fruits all at once, they are preferred for commercial production; their smaller stature also makes them suitable for container gardening.
Grafted tomato plants—at premium prices—have been showing up in recent years in garden centers and plant catalogs. Desirable tomato varieties are grafted to specialized rootstocks, gaining vigor, productivity, and disease resistance in the process.
In 2013, we planted grafted and nongrafted versions of three varieties of tomatoes in the Organic Gardening Test Garden and gave them identical care. In all three cases, the grafted and nongrafted plants produced similar quantities of fruits and showed similar susceptibility to foliage diseases. We saw no measurable differences.
Our verdict: Grafted plants may have distinct benefits in areas where soilborne diseases or pathogenic nematodes are prevalent, or in commercial operations where traditional disease-avoidance strategies like crop rotation are not utilized. But in our average growing conditions, they offered no obvious advantages.
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