Growing catnip (Nepeta cataria) indoors from seed provides a fresh, chemical-free source of this stimulating herb for cats. This perennial herb, part of the mint family, contains nepetalactone, which triggers a harmless, euphoric response in many felines. Starting catnip from seed allows for complete control over the growing environment and the quality of the final product. Successful indoor cultivation requires attention to specific conditions, particularly light and moisture, which differ from outdoor growing.
Gathering the Right Supplies
Successful indoor catnip cultivation requires selecting equipment that mimics its preferred growing conditions. Containers must have drainage holes, as catnip roots are susceptible to rot in saturated soil. Start with a container 3 to 4 inches deep, but seedlings will eventually need an 8 to 10-inch diameter pot to accommodate mature root growth.
Use a lightweight, well-draining seed-starting mix for the planting medium, as it offers better aeration and a sterile environment than standard potting soil. Catnip requires full sun, meaning at least six hours of direct light indoors. If a sunny, south-facing window is unavailable, use a dedicated light setup, such as LED grow lights or fluorescent shop lights, positioned a few inches above the seedlings. A spray bottle or bottom-watering tray is useful for gently moisturizing the seeds without displacing them.
Sowing the Seeds and Encouraging Germination
Catnip seeds often have a natural dormancy that requires cold stratification to ensure reliable sprouting. To simulate the natural winter cycle, place the seeds on a damp paper towel, fold it, and seal it inside a plastic bag or container. Store this in the refrigerator for three to four weeks before planting. This moist, cool treatment significantly increases the germination rate.
Once stratified, sow the seeds on the surface of the moistened seed-starting mix. Since the seeds are small, cover them with only a very thin layer of soil, about 1/8 inch deep, or press them lightly onto the surface. The ideal soil temperature for germination is 65 to 75 degrees Fahrenheit, which can be maintained using a seedling heat mat. Keep the soil consistently moist with a gentle misting bottle. Seedlings should emerge within seven to fourteen days.
Establishing and Maintaining the Indoor Catnip Plant
After the seedlings have developed their first set of true leaves, they can be thinned out to prevent overcrowding, leaving the strongest plants spaced a few inches apart. Providing sufficient light is necessary for healthy growth, so maintain a consistent light schedule of 12 to 16 hours per day using your grow lights. Insufficient light will cause the plants to become “leggy,” meaning they stretch and become spindly as they search for a light source.
When the plants are a few inches tall and have established a robust root system, they should be moved to their final, larger containers with fresh potting mix. Proper watering involves letting the top inch of soil dry out completely between waterings. Catnip is highly susceptible to root rot if overwatered. Water the plant thoroughly until a small amount drains from the bottom, then discard any excess water in the saucer.
To encourage a full, bushy plant, regularly pinch back the growing tips once the plant has reached about six inches in height. Pruning involves snipping off the stem just above a set of leaves, which stimulates new growth from the nodes below. You can begin harvesting the leaves and stems when the plant is at least eight to ten inches tall and just starting to develop flower buds. Harvest by cutting the stems about one-quarter inch above a leaf node, leaving at least a few inches of growth to allow the plant to quickly regenerate.
Indoor environments can occasionally attract pests like spider mites and fungus gnats, especially if humidity levels are high. Fungus gnats often indicate overwatering, so correcting the moisture level is the first step in control. A gentle spray of insecticidal soap or neem oil can manage spider mites, which are often found on the undersides of leaves. Regular harvesting and pruning help maintain air circulation, which naturally discourages pest and fungal issues.