Verbena is a popular flowering plant, often grown as a low-growing or trailing annual, providing consistent color throughout the warmer months. Its long bloom period and natural drought tolerance make it a favorite for container gardens and sunny borders. Deadheading, or removing spent flowers, is generally necessary for many varieties of verbena to ensure the plant continues to produce new blossoms.
Why Deadheading Is Essential for Verbena
Deadheading manipulates the plant’s natural reproductive process to achieve continuous blooming. The primary goal of any flowering plant is to produce mature seeds. Once a flower fades, the plant begins to focus its energy on developing the seed head, known as “setting seed.”
Removing the spent flower heads before seeds mature effectively tricks the plant into believing its mission has failed. This prevents the plant from funneling energy into seed production. Instead, these resources are redirected toward vegetative growth and the creation of new flower buds.
This redirection forces the verbena to produce a continuous supply of new blooms until the first frost. Without this intervention, many hybrid and annual varieties will slow or completely stop flowering after the initial flush fades. Deadheading also prevents unwanted self-seeding.
Step-by-Step Guide to Deadheading
The process of deadheading verbena is straightforward, but precision encourages the best response. Begin by gathering clean, sharp tools, such as small pruning snips or secateurs, as a clean cut minimizes stress and the risk of disease transfer. Identify the spent flower heads, which will appear faded, dull, or wilted.
Trace the stem of the spent flower cluster down to the nearest healthy leaf set or a developing side bud, known as a node. This node holds the potential for new growth. Make a clean cut just above this point, ensuring you do not cut into the healthy foliage.
This targeted cut encourages the growth of two new shoots from the node, each likely producing a new flower cluster, thereby increasing the plant’s density. A common mistake is cutting too low on the stem, which removes valuable foliage needed for photosynthesis, or cutting too high, which leaves an unsightly stem nub.
For the most prolific blooming, repeat this process weekly throughout the peak growing season, or whenever a substantial number of flowers appear spent. After clipping, remove the waste material from the base of the plant, as decaying matter can harbor pests or fungal issues.
Special Considerations for Different Verbena Varieties
While individual deadheading is ideal for most varieties, the exact technique varies depending on whether the plant is an annual or a perennial. Many popular trailing and mounding varieties, such as Verbena x hybrida hybrids, are grown as annuals and respond well to a more aggressive approach. Instead of snipping each spent flower, these plants benefit from periodic “shearing” or “mass cutting.”
Shearing Annual Varieties
Shearing involves cutting back the top quarter or third of the entire plant when the first major wave of blooms starts to dwindle. This mass removal of old growth rejuvenates the plant, prevents legginess, and promotes a fuller, bushier shape with a fresh flush of flowers. To avoid shocking the plant, remove a maximum of one-third of the plant’s total mass at any single time.
Perennial Varieties
Perennial verbena varieties, such as the tall Verbena bonariensis or Verbena canadensis, have different maintenance needs. These upright types may not require deadheading for continuous bloom, as they are bred to flower reliably. However, a hard cutback of about one-third mid-season can manage excessive height or restore a tidy appearance if the plant becomes floppy or sparse.