As careful as we attempt to be, both indoor and outdoor plants will often be the victim of breakage or damage. Freezing weather and wind are often the culprits when outdoor plants are damaged. Indoor plants are susceptible to a number of injuries, including those caused by playful kids and animals or being moved from place to place. Often, plants will rejuvenate themselves with a little bit of human assistance.
Prune any broken stems or branches with a pair of sharp pruning shears, but don't prune outdoor plants until spring, when there is no danger of more freezing. Newly pruned plants will be more susceptible to further damage.
Stimulate new growth on outdoor or indoor plants by pruning broken stems or branches to within 1/4 inch of a live bud or a live branch. Move newly pruned houseplants from bright sunlight to indirect sunlight for 2 to 3 weeks.
Repair stems that are damaged but not completely broken. Put a stake in the soil and tie the plant loosely to the stake above and below the damaged spot, using a strip of soft fabric or nylon stocking. If the stem is small, try making a splint out of two popsicle sticks. Put one stick on each side of the stem and tie loosely with a piece of string. This doesn't always work, and if the plant doesn't return to normal growth, it should be pruned.
Repot houseplants if the roots are growing through the drainage hole. You can also tell if a plant is root-bound because it will often shrink away from the inside of the pot in a mass of roots.
Remove broken houseplants from their pots if you suspect they've been damaged by over-watering. Wrap the roots gently in a soft towel, and let the towel absorb the water. If necessary, wring out the towel and reapply it until the roots quit draining. Use a clean pair of scissors to trim away any mushy or brown roots.
Replant outdoor plants damaged by frost heave as soon as possible. Frost heave is caused by repeated freezing and thawing, which pushes the roots up from the soil. If the ground isn't frozen, push the roots back into the soil with your fingers. Otherwise, wait until the soil thaws, and dig deep enough to replace the roots.