A popular flowering annual, petunias add color to the garden from spring until the first frost of autumn. These profusely blooming flowers are available in a range of colors and sizes, making them a suitable addition to both flower beds and pots. Because of their long flowering season, the plants often become unkempt looking after a time. Removing the spent blooms, or deadheading, improves their appearance. Deadheading also stops seed production, encouraging the petunias to continue flowering throughout the warm months.
Inspect the petunia bed once weekly while they are in flower. Look for flowers that are beginning to wilt as well as for stems where the petals have already dropped and are now forming seed pods.
Grasp the stem between your forefinger and thumb, ¼ to ½ inch beneath each spent flower. Pinch the entire flower head off the plant and discard or compost.
Deadhead the entire plant at mid-season or when the plant begins to look leggy and overgrown. Trim off the top 3 to 5 inches of the petunia with a pair of shears. The petunia will return to full bloom within a couple of weeks after severe deadheading.