Growing your own supply of Nepeta cataria, commonly known as catnip, from seed indoors provides fresh, readily available herb for your pets or for use in teas. This herbaceous perennial, a member of the mint family, contains the compound nepetalactone, which is responsible for the herb’s distinct scent and effect on many felines. Starting from seed gives you complete control over the plant’s environment, ensuring a pesticide-free product and a continuous source of fresh leaves.
Essential Materials and Preparation
Before planting, gather the correct supplies to ensure successful indoor growth. Begin by selecting high-quality catnip seeds from a reputable source, as seed viability affects germination rates. You will need a container with drainage holes, preferably at least 8 inches wide and deep for the mature plant, to prevent waterlogging and root rot.
The growing medium should be a light, well-draining seed-starting mix, often containing perlite or vermiculite to help aerate the roots. While catnip is tolerant of various soils, a mix formulated for herbs promotes healthy initial growth. Because natural sunlight is often insufficient indoors, plan to use supplemental lighting, such as LED or fluorescent grow lights, to mimic the plant’s outdoor preference for full sun. Maintain a consistent room temperature, ideally between 65°F and 75°F, for optimal seed starting.
Sowing and Germination Techniques
Catnip seeds possess a tough outer shell, which can be a barrier to sprouting, so stratification is highly recommended to improve germination success. One method involves placing the seeds in a plastic bag in the freezer overnight, followed by soaking them in warm (not boiling) water for 12 to 24 hours to soften the seed coat. This simple cold and moisture treatment helps break the seed’s dormancy.
After stratification, sow the seeds very shallowly, covering them with only a thin layer of soil (about 1/8 to 1/4 inch deep), or simply pressing them onto the moist soil surface. Mist the surface gently with water to avoid displacing the seeds, then cover the container with a clear plastic dome or plastic wrap to create a high-humidity environment. Place the covered container in a warm spot, ideally 70°F to 80°F, to encourage sprouting.
The seeds should germinate within 10 to 20 days if stratified; un-stratified seeds may take up to four weeks. Once tiny seedlings appear, immediately remove the plastic cover to prevent fungal growth and transfer the container to its permanent location under the grow lights. Keep the soil consistently moist but not saturated during this delicate stage to support the young roots.
Ongoing Care for Indoor Catnip
Providing adequate light is the single most important factor for thriving indoor catnip, as too little light results in pale, spindly, or “leggy” growth. Catnip needs a light cycle of 14 to 16 hours per day from a grow light to simulate the long summer days it prefers outdoors. Position the light source a few inches above the seedlings, adjusting the distance as they grow to prevent burning while ensuring they receive enough intensity.
Watering requires attention; catnip is susceptible to root rot if overwatered, so allow the top inch of soil to dry out between sessions. When watering, soak the container thoroughly until water drains from the bottom holes, then discard the excess water from the tray. Once the seedlings have developed their first set of true leaves, thin them out by snipping the weaker ones at the soil line to leave only the strongest plants, preventing overcrowding and promoting better air circulation.
Catnip does not require heavy fertilization and thrives in average soil conditions. However, after the plants have established their true leaves, a weak, diluted liquid fertilizer can be applied every two to four weeks to encourage prolific leaf production. Maintaining good air movement is helpful, as catnip can be prone to powdery mildew in stagnant, humid conditions, which can be mitigated by a small fan directed near the plants.
Harvesting and Pruning for Continued Growth
Begin harvesting leaves once your catnip plants are mature, typically around 6 to 8 weeks old or when they reach a height of 6 to 8 inches. To harvest, use clean, sharp shears to cut the stems just above a leaf node, which is the small bump where a set of leaves emerges. Cutting above a node encourages the plant to branch out, resulting in a bushier plant that yields more leaves.
Avoid removing more than one-third of the plant at any single harvest to prevent stressing the plant and ensure continued growth. Regular pruning is beneficial, as it keeps the indoor plant compact and delays flowering; once the plant flowers, nepetalactone oil production in the leaves decreases. If you plan to dry the harvest, tie the cut stems together and hang them upside down in a cool, dark, and well-ventilated area until they are completely dry, then store the dried leaves in an airtight container away from light.