|My tomato plants are growing taller that than 5' stakes. Is it OK to clip the tops so they don't grow over?|
|The total yield of staked plants is often lower than similar plants that are not staked. You have to prune off side shoots and branches to support the plant with a stake and that actually reduces the total leaf surface of the plant. The leaf surface is the site of the plant's food manufacturing operation, so less leaf surface means a smaller total food supply, and that affects total yield.
Not all tomato plants need staking. Determinate tomatoes stop growing at a certain height -- usually when they're fairly short. They stop growing because the main stem forms a flower bud at the top that produces fruit. Tomatoes with an indeterminate growth habit will continue to grow in height throughout the season if you feed them well and let them take off.
Pruning means pinching off the shoots or "suckers" that sprout from the stem in the crotch right above a leaf branch. If you let a sucker grow, it simply becomes another big stem with its own blossoms, fruits and suckers! With staked or trellised tomatoes, pinch off the suckers and just keep the energy of the plant directed at one (sometimes two to three) main stems.
If the plants are healthy they just grow big. Indeterminate plants will grow indefintiely until frost stops them. Based on my experience, as long as you are getting great tomatoes I wouldn't worry about pruning them.
Enjoy your crop!