University of Illinois Extension

Pruning and Staking Tomatoes

The main goal of pruning and staking tomatoes is to keep fruits off the ground, protect the fruit from sunburn and get a decent crop, said Maurice Ogutu, U of I Extension horticulture educator.

"Staking and pruning also expose leaves to full sun and reduces competition between suckers and the developing fruit," said Ogutu. "Tomatoes can be supported by stakes, cages or trellises. The type of support to be used depends on tomato growth habit.

"Tomatoes are divided into two different types namely determinate and indeterminate varieties based on their growth habits."

The determinate varieties have short to medium vine lengths. Plants are heavily branched and growth stops when they start flowering. Every branch tends to end up with a flower cluster. The determinate varieties can be staked or caged but not trellised. Determinate varieties are not heavily pruned as most of the fruit is produced on the branches. Some of the determinate varieties are Celebrity, Bush Steak, Mountain Pride, Rutgers, and Super Tasty.

Ogutu said the indeterminate varieties continue to grow and produce leaves and flowers until the first frost. They are heavily pruned when trellised, moderately pruned when staked, and lightly pruned when caged. Some of the indeterminate varieties are 'Better Boy', 'Big Beef', 'Big Pink', 'Brandy Boy', 'Brandywine', and 'Floradel'.

"Pruning is the removal of small shoots that join the stem," he said. "This reduces competition between the suckers and the fruit. Pruned plants produce larger and an earlier fruit as most of the plant energy is channeled into the fruit."

Remove the shoots when they are four inches long as removal of larger suckers may lead to injury to the plant. Remove a sucker by grasping it between your thumb and second finger and bending it to the side until it breaks. It is advisable to do this early in the day when plant is still crisp. Do not cut suckers with a knife as this can lead to spread of diseases. Limit the branches of indeterminate varieties to two to three fruit producing branches by selecting the main stem, the sucker that develops immediately below the first flower cluster, and another sucker below that. Remove all other suckers, and periodically remove additional suckers that develop on the selected branches.

"It is important to decide on type of support before setting plants in the garden," Ogutu noted. "Plants that are to be supported using trellises are set closer than plants to be staked or caged. Plants to be caged are set further apart than plants to be staked. Alternatively you can choose the type of support based on how the plants were set in your garden."

Staking tomato plants requires metal or wooden stakes. The wooden stakes need to be at least one inch square. The sections of concrete reinforcing rods can also be used as stakes. Determinate varieties require three to four feet long and indeterminate varieties require stakes that are five to six feet long.

"Do not use chemically treated wood," he added.

The plants need to be spaced about two feet apart within the row. Place the stake next to each plant or every other plant three to four inches away the base of the plant. Avoid the side where the first flower clusters appear. Tie individual branches to the stake with a polyethylene cord or sisal twine by looping it loosely around the plant. Continue to prune and tie the plant as it grows. Do not tie the plant below the flower clusters. When staking determinate varieties, remove the first suckers only.

Caging tomato plants requires wire cages made from concrete reinforcing wire. Make cages of about 18 inch diameter with openings that can allow hands to go through (about six-inch openings) when picking fruits. Indeterminate varieties require taller cages that are about five feet tall and determinate types need shorter cages about two to three feet tall. Anchor the cages around the plants. Set tomato plants three feet within the row and put a cage over each plant. Push the legs into the ground to anchor the cages. Plants are pruned to four to five fruiting branches and keep turning in ends of the branches back into the cage.

For trellising posts anchored in the ground about 20 feet apart and tops about six feet above the soil surface are required.

"Stretch a piece of barbed wire between the tops of the posts," he said. "Attach a length of twine to the wire above each plant. Tie twine to the base of each plant and wrap plants around the twine as they grow or tie them with plastic clips. Use a separate cord for each stem when trellising two stems per plant."