These old-time tomatoes were most likely grown in your ancestors' gardens back before 1940, which is when hybridization of tomatoes began. Heirloom tomatoes are full of a robust flavor not found in hybrid tomatoes, and they come in an assortment of shapes and colors besides just the typical tomato red. Although heirloom tomatoes are relatively easy to grow, their plants may produce fewer tomatoes than hybrid varieties, so be sure to plant a few extra ones.
Prepare your garden site once all chance of frost has passed and the ground is workable. Till the site and work in organic compost or well-rotted manure to make the soil well-draining.
Dig a hole twice as wide and three times as deep as the root ball of your plant, and add a handful of balanced fertilizer (e.g. 10-10-10) to the hole. Set your tomato plant into the hole so that most of the stem is below ground level, with the top two sets of leaves right above the ground. Burying your tomato plant deep ensures stronger roots and a sturdier plant. Fill in the hole with soil and firm the top over with your hand. Space each plant about 3 feet apart so they have room to grow and have adequate air circulation.
Water your tomatoes well after planting and water them frequently, using a soaker hose or drip irrigation system once a week. Allow the water to run slowly for one hour to drench the roots. Avoid overhead watering, which does not adequately supply water to the plants. Tomato plants tend to naturally droop in warmer weather; this is not an indication of needing water. Only water if the soil is dry.
Feed your plants with a liquid fish fertilizer at the time of planting. It is a good source of nitrogen. Once the plants start to flower, use a fertilizer with higher phosphorous and potassium and lower nitrogen, such as a 5-10-10. Liquid fertilizer works best and should be applied once a month after flowering begins. Water well after applying.
Provide adequate amounts of magnesium and calcium for better fruit production by sprinkling epsom salt (high in magnesium) and ground-up oyster shells (good source of calcium) around the base of each plant once it starts to flower. Water well after adding.
Apply a 3- to 4-inch layer of straw mulch around your tomato plants to help them retain moisture and control the temperature of the soil. Mulching also keeps tomatoes off the soil as they ripen, which helps prevent disease.
Place a stake next to each tomato plant, and tie the main stem to the stake with string. Staking is a must, since the plants can grow up to 6 feet tall and need good support so the stems don't break from the weight of the tomatoes. Another option is to use either an old ladder or a trellis between plants, tying the main stem of each plant to either side of the ladder or trellis. Retie as the plant grows.