For a gardener, few things are more disheartening than accidentally breaking the stem on a healthy, vigorous plant. Even with gentle handling, tomato stems snap easily when transplanting or staking, leaving the gardener with a sometimes large branch that seems doomed to wither and die without ever having the opportunity to produce fruit. Fortunately, tomato stems root easily in either water or moist soil, making it possible to save that broken branch if you act quickly.
Remove any leaves on the bottom 4 inches of the branch. Leave at least three or four healthy leaves on the end of the stem. The plant needs foliage to produce food and grow strong roots.
Insert the bottom 2 to 4 inches of the tomato stem in moist soil. Although you can start the cutting in a glass of water, or in individual pots filled with starter soil, rerooting the seedling directly in the garden eliminates the need to transplant the seedling once roots form.
Firm soil around the base of the stem and mound the soil slightly, covering several inches of the stem.
Water thoroughly and keep the soil moist until the seedling shows signs of new growth. Roots form rapidly and new growth may be observed within a few days to a week.
Water deeply once a week and fertilize with water-soluble fertilizer every two weeks.