The Nepeta x faassenii cultivar ‘Cat’s Pajamas’ is a highly regarded perennial, valued for its compact, mounding form and intense indigo-blue flowers that bloom profusely throughout the season. This catmint hybrid stands out for its tidy growth habit and early bloom time, providing long-lasting color in garden borders. Gardeners often inquire about how this robust, herbaceous perennial survives the dormant winter months. Understanding the plant’s natural response to cold ensures its longevity and vigorous return next season.
Hardiness and Dormancy Appearance
This catmint cultivar is resilient, classified as a hardy perennial that thrives across a wide range of climates, generally surviving in USDA Hardiness Zones 3 through 8. Hardiness means the plant’s underground root crown can withstand extreme winter low temperatures and regenerate new growth in the spring. As autumn progresses and daylight hours shorten, the plant transitions into dormancy to conserve energy.
The visual change is dramatic, as ‘Cat’s Pajamas’ is an herbaceous perennial, meaning all above-ground growth dies back. The vibrant green foliage turns yellow in the fall before collapsing into a mass of gray-brown stems and leaves. This dead material serves as a natural insulating layer, protecting the living root crown just below the soil surface. Gardeners should recognize this appearance as a normal, healthy process of winter preparation.
Preparing ‘Cat’s Pajamas’ for Cold Weather
Drainage and Watering
The most significant action a gardener can take in late fall is ensuring the plant is situated in well-drained soil, as a combination of freezing temperatures and waterlogged conditions is the greatest threat to the root crown. Catmint roots do not tolerate sitting in standing water, which can lead to rot before the ground freezes solid. Reducing watering significantly in the fall helps the plant naturally begin its dormancy process and prevents excessive moisture accumulation around the roots.
Pruning Decisions
Gardeners must decide whether to prune the dead stems in the fall or wait until spring. The preferred method is to leave the material intact until the cold passes. The standing, dry foliage offers natural insulation and protects the crown from harsh wind and temperature fluctuations throughout the winter. If pruning is necessary for aesthetic reasons, the stems should be cut back to four to six inches above the soil line to leave some protective buffer.
Applying Mulch
Mulching provides an additional layer of thermal protection, but it must be applied correctly to avoid smothering the plant. A layer of organic material, such as straw or shredded leaves, should be spread around the base of the plant only after the ground has completely frozen. Applying mulch too early can trap warmth, which may confuse the plant and inhibit proper dormancy, or provide a nesting site for rodents that can damage the crown. This protective layer helps to regulate soil temperature and prevents the heaving and thawing cycle that can lift and damage shallow roots.
What to Expect When Spring Arrives
The return of warmer weather signals the end of dormancy. ‘Cat’s Pajamas’ is often one of the earliest perennials to emerge, sometimes showing signs of life as early as March in moderate zones. New, light green basal growth will sprout directly from the crown, often while the old, brown stems are still visible. This new growth is the cue for the final necessary pruning step.
Cut back all remaining dead, gray-brown winter foliage completely to the ground level, or just above the emerging new shoots. Clearing this debris allows sunlight and air to reach the new growth, preventing potential fungal issues and promoting a neat, compact habit. Once the new shoots are clearly visible and actively growing, apply a light application of a balanced, slow-release fertilizer or a thin layer of compost around the base. This provides the necessary nutrients to fuel the plant’s rapid spring growth and supports vigorous, season-long flowering.