Verbena (Verbena spp.) is a sun-loving flowering plant that is winter hardy in U.S. Department of Agriculture plant hardiness zones 7 through 10 and grown as an annual in USDA zones 6 and lower. With long-blooming, showy flowers of violet, purple, rose, red, yellow or white, verbena is a bright, low-maintenance addition to any summer garden.
1. A Sunny Spot
Verbena needs full sun to develop its brilliant, long-lasting summer colors. Without a full day of sun -- between eight to 10 hours -- verbena becomes susceptible to powdery mildew, a fungal disease, and will not produce the exceptional clusters of blooms for which it’s known. Verbena is not overly particular about the soil it lives in, but does require a well-drained location with an occasional application of a slow-released, complete fertilizer.
2. Verbena Blooms
With a little pruning, verbena will bloom from May through to October. As the flowers begin to fade, cut back the plant by roughly one quarter of its height at the time of cutting, ensuring all faded blooms are removed. Within a couple of weeks the plant will begin to blossom once again. If verbena is grown as a perennial, wait until the spring for a severe pruning; cutting the plant back in the fall may impair its hardiness. While verbena is drought tolerant, excessive dryness over the summer may cause the blooming to slow and additional water during dry periods will help keep the flowers strong.
3. Planting Verbena
Along with needing full sun, verbena will not tolerate crowding, lack of air circulation or wet conditions. Any problems that do occur with verbena are typically due to poor conditions in the garden and not with the plant itself. However, new plantings do need regular water to get the plants established. Keep the leaves dry by watering at ground level to help avoid fungal problems that can develop on plant stems and leaves due to high humidity.
4. Uses in the Garden
A fast grower, verbena will develop from 6 inches to 6 feet high and spread up to 5 feet wide, depending on the variety. Trailing and low-growing varieties like homestead purple (Verbena canadensis "homestead purple") or apple blossom (Verbena canadensis "apple blossom") grow well in containers, hanging baskets, window boxes, or as ground cover plants and provide long-lasting color. Bushy, or upright varieties can fill a garden bed with bright summer color or add interest to larger containers. Consider tall verbena (Verbena bonariensis), a quick-growing verbena variety, reaching 3 to 6 feet high and up to 3 feet wide, or blue princess verbena (Verbena X hybrida "blue princess") a bushier variety that reaches 1 foot high with a 3 foot spread.