Verbena is a popular genus of flowering plants that provides continuous color throughout the warmer months, making it a favorite for garden beds and containers. Proper pruning encourages a bushier habit, maintains a pleasing shape, and maximizes flower production across the growing season. Understanding when and how to apply different trimming techniques is the foundation for keeping these plants healthy and vibrant.
Understanding When to Prune
The timing of pruning depends on the goal, whether it is structural renewal or mid-season maintenance. Structural cuts are best reserved for early spring, just before new growth begins to emerge. Removing old, dead, or woody stems at this time directs the plant’s energy into developing fresh, vigorous shoots.
During the summer, lighter pruning is performed as routine maintenance to keep the plant tidy and stimulate more flower production. This trimming is often done when removing spent flower heads. For perennial types in colder regions, cease any final light cutback approximately six weeks before the average first frost date to prevent winter damage.
Late fall or early winter cuts are not recommended for perennial Verbena varieties. The remaining foliage offers a layer of protection against harsh winter conditions. These dead stems should be removed in the spring once the threat of severe cold has passed.
Deadheading for Continuous Blooms
Deadheading is the process of removing faded or spent flower clusters and is the most frequent pruning activity for Verbena. This practice prevents the plant from setting seed, which signals it to cease flower production. By interrupting the seed-setting cycle, the plant is stimulated to produce new blooms, extending the flowering period.
To deadhead effectively, locate the faded flower cluster and make a clean cut just above the nearest set of healthy leaves or a lateral bud. This cut point is where the plant will initiate new growth and subsequently produce another flower stalk. Regular deadheading throughout the summer maintains a neat appearance.
Many modern hybrid Verbena varieties are considered “self-cleaning,” meaning they drop their spent flowers without intervention. However, deadheading or a light trim is still beneficial. Using clean, sharp hand shears or simply pinching with your fingers is effective for this light maintenance.
Major Cutbacks and Species Variations
Major cutbacks are structural pruning events that go beyond simple deadheading. They are necessary to manage the plant’s size and shape, especially when stems become long and sparse, a condition known as legginess. When the overall bloom quantity decreases, a more aggressive cutback is warranted to force a flush of new, dense growth. This technique involves reducing the overall size of the plant by one-quarter to one-half.
The severity and timing of a major cutback depend on whether the plant is an annual hybrid or a perennial species. Trailing or mounding garden Verbenas (V. x hybrida), often treated as annuals, benefit from a hard cutback of up to one-third of their length in mid-summer to rejuvenate them. This cut stimulates lateral branching, leading to a denser shape and a strong rebloom.
Perennial species, such as Verbena bonariensis (tall Verbena), require a different approach. They should not be cut back hard in the fall; their woody stems should be left standing for winter protection. Cut these stems back nearly to the ground in early spring, right as new basal growth emerges. Tools like bypass hand pruners or shears are appropriate for these larger cuts.
Fertilization
Providing a balanced fertilizer following the cutback can help fuel the plant’s recovery and subsequent vigorous new growth.