Dee Lawrence
Adams County Master Gardener

Tomatoes are the most popular vegetable in the summer garden. They are easy to grow and with the right care and tending will continue to produce fruit in abundance all summer until frost. Ideal conditions for productive tomato plants are well-drained soil and a site that receives at least 8 hours of sunlight a day. They are a warm-season vegetable and begin to set fruit after nights have warmed to between 58 and 70 degrees. The best time to plant in this area of South Central Pennsylvania is after May 10th when danger of frost is past.

Because tomatoes are so easy to grow, many gardeners attempt to start tomato plants from seed. Not only can they save money by starting their own, but they also get to choose from many more interesting and unusual varieties that are not always available locally. Tomato seeds should be planted indoors about 6 to 8 weeks before they are set out in the garden. Sow seeds in shallow trays in sterile potting soil; do not use common garden soil. The seeds do not require sunlight until they have sprouted and will germinate quickly in a warm spot, such as on top of the refrigerator or the TV/VCR. An ordinary heating pad set on "Low" placed under the seedling trays can also provide a safe bottom heat. They should not be allowed to dry out.

Transplant into separate cells or cups when they have grown 4 leaves so there is more space for root development. Additionally, there will be less transplant shock when they are set out in the garden because the roots will not have to be disturbed again. Before the plants are ready to be transplanted into the garden, they need to be "hardened off " by spending a few hours for 3 to 5 days in a sheltered, sunny spot where they can become accustomed to outdoor conditions. A seedling ready for the garden will be at least 6 to 9 inches tall, with healthy, dark green foliage, and a stem as thick as a pencil.

Tomato plants should be set 18 to 24 inches apart in rows that are 36 inches apart or in raised beds 4 to 5 feet wide with plants set on 18 to 24-inch centers. The root ball should be at least 4 to 5 inches deep. If plants are tall and leggy, remove all but the top 6 leaves and lay the plant stem horizontally in a small trench 4 or 5 inches deep with only the top foliage sticking out of the ground. This encourages a much stronger root system because tomatoes have the ability to form roots along this underground stem. Since tomato roots are fairly superficial, any cultivating should not be deeper than 2 inches.

Tomatoes are heavy feeders, so if the soil is poor, you may want to till in about 3 1/2 pounds of 5-10-10 fertilizer per 100 square foot either before the plants are set or one half of the fertilizer prior to planting and the other half 3 weeks later. Adding too much nitrogen can result in bushy green plants but less fruit production. Water well in the hole after it is half filled with soil and the seedling.

If the plants are going to be staked to keep the fruit off the ground, install the stakes when the plants are set out so as not to damage the roots later. A 5 or 6 foot stake 1 to 1 1/2 inches in diameter is sufficient. Cages can be made from 6-foot wire fencing using rebar for support so long as the holes in the mesh are large enough to allow for picking the tomatoes. Cages should be 24 inches in diameter for large varieties and 18 inches for smaller. Determinate plants like patio tomatoes usually do not need staking. Indeterminate varieties continue growing all season and may have vines that extend to 12 feet. Check seed packets and plant identification tags for these important distinctions.

Pruning is a common practice to conserve plant energy for fruit production. Side shoots that appear in the axil of the leaf stem where it is attached to the main stem must be pinched off. Most gardeners limit the plant to three main stalks and remove all others as soon as they develop. Pruning is a weekly process but necessary to maintain good air circulation around the plant.

Tomatoes only grow when they have plenty of moisture in the soil, at least to a depth of 6 inches. They need an inch of water per week. When rainfall is inadequate, irrigate to 1/2 inch twice a week. Overhead watering should be done in late afternoon, with enough time for the foliage to dry off before night. Tomatoes grow a lot during the night, but only if adequate moisture is present. A safer watering method is drip irrigation; it conserves water, places it right in the root zone where it is needed, and does not encourage diseases, especially fungal diseases such as fusarium wilt or verticillium wilt.

Tomatoes thrive on organic material in the soil. One or two inches of compost applied evenly over the bed and worked into the top 2 inches acts as a continuous source of nutrients for the plants. Compost contains healthy microorganisms and earthworms that break down the organic matter in the soil so it can free minerals for plant nutrition. It also discourages plant diseases and insect pests. Three inches of mulch such as straw or leaf mulch on top of the compost will prevent weed germination, conserve moisture in the soil, and combat wind and water erosion.

Whether you're a new gardener or one who's been at it for years, tomatoes can be one of the most rewarding vegetables to grow. Biting into a meaty, tangy tomato still warm from the afternoon sun is what summer is all about.

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