Tomato plants have a tendency to become large and spindly, which can cause their stems to sprawl over the ground. Plants that touch the ground are more susceptible to pests, mold and disease and often don't get enough sunlight. You can train tomato vines to a trellis, which keeps your plants tidy and upright. Trellis systems also save space, so you can fit more plants in your garden. There are many different trellis options and techniques, but for the home garden, stick with simple designs.
Buy or make a trellis with materials that last a long time and a simple design. Choose from wire tomato cages, wooden or bamboo stakes that form a teepee shape, or stakes and twine for a woven trellis. If you are planting indeterminate varieties, use tall stakes or cages, as this type of tomato plant can grow to 6 feet tall.
Assemble your trellis around young tomato plants when they're about 12 inches tall. Press tomato cages into the dirt around each tomato plant. Press wooden or bamboo stakes into the ground at an angle, forming a triangle or square around the plant, and fasten the tops of the stakes together with twine for a teepee trellis.
For a woven trellis, place a stake between each tomato plant in the row. Attach one long string of twine from the first to the last stake in the row, weaving back and forth between each stake. Wrap the twine around the last stake, and then weave the string back down the row so each stake has one string on each side, and the strings form a long "X" between each stake. The first twine layer in a woven trellis should be low to the ground; you will add higher layers as the plants grow.
Guide the vines to the trellis and attach each vine to your trellis with a loop of twine or a strip of old pantyhose. Do not tie the loops too tightly.
Train the tomatoes as they grow, adding more loops of twine or pantyhose. Add additional layers of twine to your woven trellis when the plants grow above the first string. Space layers about 8 inches apart. Wire cages may need extra support when the plants grow to the top, especially when tomatoes appear on the vines. If your cage seems top-heavy, add a few wooden stakes around the outside edge of the cage. Fasten the stakes to the top level of your wire cage for extra support.