The Soil Your tomato patch needs to fit the following description:
Making Your Bed Tomatoes grow best in slightly acidic soil (pH 6.2 to 6.8). If you suspect your soil isn't, get a soil test and amend accordingly. Two ways to ensure that your tomato bed is full of beneficial soil organisms and plant nutrients:
Add compost. Fork the soil to a depth of 1 foot and add two shovelfuls of compost to each planting hole. This improves drainage, increases soil fertility, and helps the soil hold water.
Grow a cover crop. Plant a grain or legume crop—sometimes called green manure—for the purpose of chopping it down and adding it to the soil. One tried-and-true way is to plant hairy vetch (a nitrogen-fixing legume) in your garden bed in fall. In spring, cut it down and plant your tomatoes in holes you carve through the matted residue and stubble. This provides both nitrogen and an instant mulch that preserves moisture and keeps weeds from sprouting.
Food and Water Fertilizer. Don Boekelheide, our test gardener in Charlotte, North Carolina, scratches a 5-3-3 organic fertilizer and a handful of rock phosphate into the soil around his tomato plants twice during the growing season—once when the plant is a foot tall, and again when it flowers. Spraying your plants with a fish emulsion or kelp solution two or three times a season also boosts vigor, which helps the vines outgrow diseases.
Water. Give your plants an inch of water each week when it doesn't rain to prevent fruit from cracking or developing blossom-end rot. The most efficient method is a drip system or inexpensive soaker hose.
Weed Control Mulch suppresses weeds and conserves moisture. Any mulch is better than none, but a comparison study done by the USDA in Beltsville, Maryland, showed that tomatoes mulched with mown vetch (see "Grow a Cover Crop," above) produced especially robust root systems and outperformed those mulched with plastic. We recommend a 3- to 4- inch layer of dried clippings, leaf mold, straw, or even shredded newspaper—all of which decompose and feed soil organisms—over plastic. Clear or IRT (infrared transmitting) plastic mulches make sense where summers are short, because they warm the soil.
Companions Tomatoes love carrots. And onions, and basil, and marigolds. A neat row of 'Summerlong' basil or triple curled parsley looks nice and makes for an efficient use of space. West Coast Contributing Editor Willi Evans Galloway used the shady spot created by her tomato plants as a nursery bed for lettuce seedlings in her Seattle garden last summer.
Support Systems Stake or cage plants while they are small, so you don't damage branches or roots. At the Organic Gardening Test Garden, we found these methods effective:
Concrete-reinforcing-wire cages: We build them 5 feet high and 2 1/2 to 3 feet in diameter. The welded steel mesh supports even the largest plants. Until, that is, they are laden with fruit and a gust of wind whips through. Experience has taught us that weaving 8-foot bamboo poles horizontally through the cages about 4 feet off the ground and tying them to the cages keeps them upright. Debbie Leung, our Washington State test gardener, uses similar reinforcing poles but attaches them to metal T-stakes, driven into the ground between every fourth cage.
Stake-and-weave trellising: The plants are held up between lengths of twine strung between parallel rows of stakes. You can harvest more and earlier tomatoes from a limited area by spacing plants 1 1/2 to 2 feet apart (instead of 3 feet) and pounding a 6-foot stake into the ground between every other plant. As the plants grow, weave baling twine in and out of stakes and tomatoes. Do this 4 to 6 times over the growing season. John Good, of Quiet Creek Farm near Kutztown, Pennsylvania, prefers this method because it ensures good air circulation. It also makes harvesting easier.
Prune or Not? Research by Purdue University showed that pruning (by removing the branches, or "suckers," below the first main stem) increased the average fruit weight in some cases, but not the total yield per plant. Where pruning makes sense: If you stake and weave, prune the lower suckers for better air circulation; if planting in an ornamental garden, prune suckers (see illustration) for neatness. Don Boekelheide (our tester in North Carolina) prunes vigorous indeterminates to two main stems early in the season to keep them from taking over his southern garden.