Tomatoes grow along upright vines. Without proper support, the plants fall over and trail along the garden bed. While tomatoes can be left to sprawl in this manner, they are more prone to disease and insect pests. Tomatoes sitting on the ground may rot as they remain in contact with moist soil. Tomato cages are one of the simpler means of supporting tomato plants. Unlike a staked tomato, a caged tomato does not require constant pruning or tying in order to stay supported.
Plant tomato seedlings in a full-sun, well-drained garden bed after spring frost danger is past. Space the plants 6 feet apart in all directions to give ample room to the tomato's roots and to the cage setup.
Place the cage over the top of the plants after planting them. Place cone-shaped cages with the narrow end at the bottom. Center the tomato plant in the middle of the caged area.
Drive a 12-inch stake into the ground on either side of the cage, burying the stake 6 inches in the soil. Tie the cage to each of these stakes with a length of gardening twine. This anchors the cage better than the short stakes that are part of the base of most cages.
Wrap the cage with perforated plastic sheeting, available at garden centers, securing it to the cage with clothes pins. Leave the top of the cage uncovered unless a late-season frost is predicted. The plastic keeps the plant and soil warm inside the cage while also preventing insect pests from attacking young plants.
Remove the plastic once the tomato grows large enough that the leaves are touching the plastic. There is no need to tie the tomato to the cage or pull the branches through the opening, as the cage holds the plant upright with no further maintenance.