Catmint (Nepeta) is a durable, low-maintenance perennial herb known for its long season of lavender-blue flowers and fragrant, gray-green foliage. This vigorous grower is popular for borders and ground cover, attracting numerous pollinators. Propagation is the most effective way to expand garden stock, replicate desirable traits, or refresh older, woody plants. Increasing the number of plants can be accomplished through vegetative (cuttings, division) or sexual (seed) reproduction methods.
Catmint Propagation: Selecting the Right Method
The choice of propagation method depends on the gardener’s goal and the specific catmint variety. Vegetative methods, such as cuttings or division, guarantee the new plants will be clones of the parent, retaining identical characteristics like flower color and size. Division offers the fastest path to a full-sized plant, providing immediate, robust sections.
Cuttings efficiently produce many clones without disturbing the main root system. Propagating via seed allows for new genetic variations, but seeds from hybrid varieties may not grow true to the parent plant.
Method One: Propagating via Stem Cuttings
The ideal time to take catmint cuttings is during spring or early summer when the plant is producing softwood growth. Select actively growing stems that are not yet flowering, ensuring the plant’s energy focuses on root development. Using a sterile, sharp blade, take a four to six-inch cutting, making the final cut just below a leaf node where root-forming cells are concentrated.
Remove the leaves from the lower half of the stem to prevent rotting in the medium. Dipping the cut end into rooting hormone powder can accelerate root formation. Insert the prepared cuttings into a small pot filled with a light, well-draining medium, such as a mix of perlite and damp potting soil.
Cuttings require consistently high humidity and moisture to prevent drying out before roots form. Place the container in bright, indirect light, and consider covering it with a clear plastic bag or dome to create a miniature greenhouse environment. Roots typically begin to form within two to three weeks, indicated by slight resistance when the cutting is gently tugged.
Method Two: Propagating via Root Division
Root division rejuvenates older catmint clumps that have become sparse or woody in the center. This process is best performed during the plant’s dormant or semi-dormant periods, either in early spring before new growth begins or in early fall. Start by cutting the existing foliage back by about one-third to reduce water loss and transplant shock.
Carefully use a garden fork or spade to dig up and lift the entire root ball. The dense clump can then be separated into smaller sections using a sharp spade, a knife, or by prying it apart by hand. Each resulting division must contain a healthy portion of roots and at least one viable growth bud.
Replant the divisions immediately at the same depth they were previously growing, ensuring the crown is not buried. Amending the new planting site with compost helps the root system establish quickly. Water the newly planted sections thoroughly and consistently to settle the soil and minimize transplant stress.
Method Three: Propagating via Seed
Catmint seeds from non-hybrid varieties often require cold, moist stratification to break dormancy and encourage germination. This step mimics the natural winter cycle, conditioning the seeds for spring growth. A common method involves mixing the seeds with damp sand or peat moss and placing the mixture in a sealed bag within a refrigerator for about 30 days.
After stratification, or if using a variety that does not require it, sow the seeds in a tray filled with a high-quality seed-starting mix. Catmint seeds generally need light to germinate, so they should be sown on the surface and only lightly pressed onto the medium. Maintain a consistent soil temperature between 60 and 80 degrees Fahrenheit for optimal germination.
Seedlings should begin to emerge within seven to twenty-one days, though germination can be erratic. Once the plants develop their first true leaves and are large enough to handle, they can be carefully transplanted into individual pots. Thinning overcrowded seedlings at this stage ensures adequate air circulation and prevents the spread of fungal diseases.
Essential Care for Newly Propagated Catmint
Hardening Off and Initial Watering
Once rooted or replanted, the focus shifts to successful transition. Plants started indoors must undergo hardening off before being permanently moved outside. This involves gradually exposing them to increasing periods of direct sunlight, wind, and outdoor temperatures over one to two weeks.
Newly planted divisions or rooted cuttings require consistent soil moisture, especially during the first few weeks of establishment. Keep the soil evenly moist but never waterlogged, which can lead to root rot. After transplanting, pruning the foliage back by about a third reduces the plant’s immediate water demands and stimulates bushier growth.
Final Transplanting
The best time to transplant new catmint into the garden is during spring or early fall when temperatures are moderate, reducing the risk of shock. Space the new plants approximately two to three feet apart to accommodate their mature, mounding size. Providing adequate space ensures good air circulation and prevents competition for soil resources.