Tomato plants are vigorously growing, warm-season vegetables. It is important to provide some sort of support for tomatoes before they are heavy with fruit and flop over onto the ground. Once on the ground, it is easier for slugs and other pests to damage the leaves and fruits. Tomato cages also increases air circulation around the leaves which prevents most plant diseases, according to University of Arizona Cooperative Extension.
Cut a piece of wire fencing that is 3 to 6 feet tall and 9 1/2 to 12 1/2 feet wide with wire cutters. The size of the wire depends on the mature size of the tomato plant. Taller plants need the larger size. Use galvanized wire with space of least 6 inches so your hands can fit inside the cages.
Bend the fencing so the width forms the diameter of a circle. The circle is 3 to 4 feet across to make reaching the fruit less of a stretch.
Connect the sides of the cylinder with plastic fence ties. Space the ties out to every 6 inches along the seam. Pull the ties down tight with a pair of pliers.
Place the tomato cage around the tomato seedling when it is first planted to avoid damaging the branches later.
Lay the branches on the wires of the tomato cage as the plant grows. Do this early in a branch's growth while it is still bendable to avoid breakage.