When To Cut Back Catmint For The Healthiest Plant Possible

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When To Cut Back Catmint For The Healthiest Plant Possible

Catmint (Nepeta) is a perennial plant that is popular among cats for its pleasant aroma and striking lavender, white, or blue two-lipped flowers. It is commonly used as a border feature or planted en masse in meadows and garden walkways. The plant’s fragrant flowers are attractive to butterflies and also repel squash bugs and aphids from invading your garden.

However, catmint’s gray-green foliage can become quite leggy and weedy, but it does not become invasive. Therefore, it is essential to trim it back to minimize self-seeding and promote a second flush of blooms. In addition, because catmint is a deciduous woody plant that withers away during the fall season, a second round of pruning is necessary to tidy it up.

You can choose to prune catmint immediately in October, but it is best to wait until early spring to avoid reinvigorating winter growth and weakening the plant, which can lead to frost damage.

When to cut back catmint

Catmint plants in early spring

J.J. Gouin/Shutterstock

Despite being easy to care for, catmint requires regular pruning to maintain healthy growth. Although cutting it back at least twice yearly is ideal, you may want to remove the plant’s damaged stems throughout the year to maintain a neat appearance. The first shearing, or “Chelsea Chop” should happen right after the woody shrub completes its first flowering cycle. Such early summer deadheading will push the plant to redirect its resources from seed production to reblooming — at least in some varieties. Moreover, as the top-heavy plant turns droopy on blooming, cutting it back should help it retain its posture and revitalize its bushy look.

The second round, or cleanup pruning, should happen around early spring, especially if you live in mild winter climatic zones, to stimulate new catmint growth. This will add visual interest to your lawn during the winter and take care of any overwintering fungal diseases and powdery mildew that can potentially hurt the fresh growth. However, if you dislike the messy, dead foliage aesthetic and live in cool temperatures, you can choose to shear the catmint during the fall.

How to cut back catmint

Person tending to catmint plants

Jana Loesch/Shutterstock

The first step to cutting back catmint is to pull out all damaged and diseased branches. To promote a potential second flush, prune all the plant’s stems down to a third of their height. This will encourage new side shoot growth and give way to possible fresh blooms. It also prevents seed production, restricting the plant’s spreading. You can alternatively shear off the catmint’s flower spikes down to the first leaf to experience another flowering round. However, ensure the disinfected gardening tool is sharp to eliminate the risk of fungi infecting the ragged cuts.

If you’re trimming catmint to prepare for the next season, lightly cut down the plant’s dead stems, leaving behind around 4 to 6 inches of growth. This will keep the catmint plant insulated from severe winter and frost damage. You can follow the same procedure for spring cleanup. While this process should last you for around three to four years, consider dividing the plant in half and replanting it for better growth and blooms.

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Dr Heidi Parkes

By Dr Heidi Parkes

Senior Information Extension Officer QLD Dept of Agriculture & Fisheries.