Catmint (Nepeta) is a perennial highly valued in gardens for its long flowering season and fragrant foliage. This durable plant produces masses of lavender-blue, purple, or white flower spikes from late spring into early summer. Varieties like ‘Walker’s Low’ or ‘Six Hills Giant’ have a strong capacity to re-bloom vigorously if managed correctly. Maximizing the flowering period and achieving a second, strong flush of blooms requires a post-bloom cutback.
Timing the Initial Cutback for Re-Bloom
Intervening at the correct moment is the most important factor for triggering a successful second bloom. The ideal time to cut back catmint is immediately after the first major flush of flowers has peaked and begun to fade, typically occurring in early summer. The plant provides visual cues that the initial blooming cycle is complete, generally when the majority of the flower spikes appear spent or are starting to turn brown.
This is also when the overall plant structure may start to look “floppy” or open in the center, indicating a decline in vigor. Waiting too long sacrifices energy the plant could be using for new growth, potentially delaying or preventing a substantial second bloom before the season ends. Cutting back too early prematurely ends the first flower show, so the goal is to intervene when the plant is approximately 50 to 75 percent finished with its initial display.
Step-by-Step Guide to Shearing Catmint
The technique required to stimulate new flowers is shearing, which is a more aggressive pruning method than simple deadheading. Shearing involves cutting back the entire plant mass, rather than just snipping off individual spent flower heads. This action signals to the plant that reproduction through seed-setting has been blocked, forcing it to redirect energy into producing new stems and a subsequent flower display.
To perform the cutback, use sharp, clean tools such as garden shears, hedge clippers, or strong secateurs to ensure a clean cut that minimizes damage to the stems. The goal is to reduce the plant’s height by one-third to one-half of its total size. For many established varieties, this translates to cutting the plant back to a uniform height of approximately 6 to 8 inches above the ground.
Cutting the stems back to this height removes the spent flowers and the upper, often leggy, foliage, resulting in a low, tidy mound. This radical pruning encourages new basal growth from the crown of the plant, which will be much denser and more robust. The new growth will rapidly develop and produce a fresh wave of flowers within a few weeks, providing color well into the late summer or early autumn.
Essential Care for a Successful Second Bloom
Immediately following the shearing process, the catmint needs focused care to support the rapid development of new growth and flower buds. While established catmint is notably drought-tolerant, the plant requires consistent moisture during this recovery phase. Water the plant thoroughly after the cutback to saturate the root zone, and maintain regular watering until new shoots and foliage begin to emerge vigorously.
Catmint is generally not a heavy feeder, and too much fertilizer can promote weak, floppy growth rather than flowers. However, a light boost can support the energy demand of a second bloom cycle. Applying a thin layer of compost around the base of the newly pruned plant or a mild, balanced liquid fertilizer can provide the necessary nutrients without causing excessive foliage growth.
Gardeners should also monitor the new growth for common issues like powdery mildew, which can occur if air circulation is poor, or for common garden pests. The dense, new foliage that emerges after shearing can be more susceptible to these issues. Once the second bloom begins, light, selective deadheading of individual spent spikes can be performed to prolong the display.