Petunias are among the most commonly used annuals both in planters and in garden beds. They are available in just about any color except true blue and come in both trailing and mounded forms. Petunia flowers prefer full sun, but can tolerate part shade, and benefit from regular deadheading and fertilizing in order to bloom all summer. If they become too long and leggy, you can cut back your petunias by up to half their length. Some of the most common series of petunia varieties are ‘Wave Petunias’, ‘Supertunia Petunias’, and ‘Surfinia Petunias’.