How to Fix Leggy Growth in Plants. You started your tomato seeds inside too early, and now they're leggy--pale and stretched out, with more stem than leaf. This can happy to any vegetables, flowering plants or house plants. Lack of light or too much nitrogen are the most common causes of this, and common wisdom is that leggy seedlings must be thrown out--but there are other ways to fix them.
Plant your leggy tomatoes, broccoli, impatiens or other plants very deep so that the extra stem portion is covered. It's okay to snap off lower branches or remove leaves to accomplish this. Extra roots will grow along the length of the stem, contributing to a stronger, stockier plant.
Dig a trench and bury your leggy plants sideways in the trench, gently curving the above-ground portion of the plant to be vertical. Even if it's not exactly vertical the plant will correct itself later, but you should remember where the root ball of the plant is during days after transplant so that you make sure it receives plenty of water.
Apply fertilizer that is low in nitrogen and high in phosphorous to encourage flowering and fruiting in plants that may be leggy as the result of over fertilization with nitrogen.
Prune leggy growth on foliage and flowering plants back as close to the stem as possible. The common wisdom is to prune only when necessary to remove dead wood or to fix a plant has grown out of desired shape. It is usually best to prune during the very start or the very end of the growing season.