Canna lilies, often admired for their bold, tropical aesthetic, bring vibrant color and large, paddle-shaped foliage to any garden setting. These rhizomatous perennials are related to ginger and bananas, thriving in warm, sunny conditions. To maintain their continuous display of flowers throughout the growing season, a common horticultural practice called “deadheading” is considered. Deadheading is the process of removing spent flowers, and applying this technique to the unique structure of the Canna flower stalk requires specific knowledge.
The Necessity of Removing Spent Canna Blooms
The decision to remove faded Canna blossoms is driven by the plant’s natural energy allocation and the desire for an extended bloom season. Once a flower fades, the plant’s biological imperative shifts from producing visual attractants to ensuring reproductive success by developing seeds. This shift diverts significant metabolic energy, specifically carbohydrates and nutrients, away from generating new flower buds and foliage growth.
Removing these spent flowers prevents seed development, effectively tricking the plant into focusing its reserves on vegetative growth and the production of new flowering stalks. This redirection of energy helps maximize the aesthetic appeal by continuously refreshing the display. A plant not burdened by seed production can push more energy back into the underground rhizome structure, supporting subsequent blooms and sustaining the plant’s overall vigor.
How to Properly Deadhead Canna Lilies
The proper technique for deadheading Cannas differs from many common garden plants because their flowers emerge sequentially along a single main stalk. The initial step involves removing the individual flowers as they wilt and shrivel. Look closely at the flower spike and snip off the faded blooms just above any lower buds or developing flowers that have yet to open. This selective removal maintains a neat appearance while allowing the remaining blooms on that spike to mature.
Once all the flowers on a particular spike have completely finished blooming and no new buds are visible, the entire flower stalk should be removed. Trace this spent stalk down to a main leaf joint or a point where new, healthy foliage is emerging. Making a clean cut at this lower point encourages the rhizome to send up a new flower stalk from the base. Using sharp, sterilized bypass pruners for this task is important to make a precise cut and reduce the risk of introducing pathogens.
Alternative Removal Method
A less common but effective method is to wait until the entire stalk is finished and cut it back down to the ground level, or just above the basal leaf structure. This technique is often simpler for gardeners but may temporarily leave a gap in the foliage until the next shoot emerges. Consistency is beneficial, as checking plants every few days ensures that the plant’s energy is continually focused on producing new blooms rather than forming seed pods. This strategic pruning allows the Canna to maintain its flowering habit until the season concludes.
Allowing Canna Seed Pods to Form
While deadheading promotes continuous flowering, some gardeners choose to allow the plant’s reproductive cycle to continue, particularly towards the end of the season. The spent flowers will give way to developing seed pods, which appear as round, spiky, green capsules. This choice sacrifices the potential for late-season blooms, as the plant commits its energy to maturing the seeds inside these pods.
Allowing the pods to dry and turn brown on the stalk is the necessary process for harvesting Canna seeds. These seeds are large, black, and notably hard, a characteristic that requires scarification—nicking or filing the tough outer coat—to promote successful germination. For those interested in propagation, collecting these seeds is an alternative to purchasing new rhizomes. Plants grown from the seed of hybrid varieties may not exhibit the same characteristics as the parent plant. This decision to bypass deadheading is a trade-off that favors future propagation over maximizing the current season’s floral display.