Answer: In general, petunias are annuals that perform best in warm, sunny weather. Some of the newer 'wave' series do not need to be deadheaded, but the older, larger flowered varieties will bloom more prolifically if spent flowers (along with some of the stem) are removed regularly. This stops seed production. If you allow seeds to develop, the plant will put most of its energy into producing seeds rather than developing new flowers. Pinch off the faded flowers along with a few inches of stem and your plants will become bushy and full of new blooms. Expect them to continue to flower until first frost.
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