Cut a 6-inch branch from one of the boxwood shrubs with your knife. Cut perpendicular to the branch as close to the parent stalk as possible.
Trim the end to a 30-degree angle and lay it aside. Use your artist's paint brush to coat the open wound on the parent stalk of the boxwood hedge with latex paint.
Find a spot on one of the larger main stalks of the other hedge that is free of blemish. Trim away the bark of the stalk and shave it so that the exposed wood is flat.
Hold the angled end of the cut branch against the exposed area of the new parent shrub. Wrap baling twine around the juncture to bind the branch to its new home. Tie a triple knot in the twine to hold it in place.
Water the plant daily. Feed it weekly. Add fertilizer around the roots of the boxwood monthly. Replace the baling twine every three months for four to five years or until the wood is completely healed.