Catnip, nepeta cataria, makes an attractive ornamental plant that can also be made into tea for humans or given to cats as a treat. About 2/3 of cats have a strong reaction to the oils in catnip, and may seek out catnip in herb gardens or perennial borders. A relative of mint, catnip grows vigorously in the garden and can be propagated by seed or divisions. Live catnip has serrated, mint-like leaves with spikes of white flowers. The related catmint varieties have purple flowers.
Like most mints, catnip tolerates a wide range of growing conditions. Moderately fertile soil that doesn’t accumulate standing puddles is enough for catnip, and in more fertile, well-drained soil, catnip grows vigorously. Tolerating pH between 6.1 and 7.8, catnip can be grown in just about any soil that will grow other types of herbs, vegetables, ornamentals or lawn turf. Except in very poor soil, catnip does not require additional fertilization or supplemental watering.
Catnip grows well in full sun to partial shade. In full shade, it can get leggy and may not flower, but will still grow. Catnip is susceptible to mildew, so a site that dries quickly from morning dew and has good air drainage is best.
Choosing a Site
Because catnip spreads rampantly, choosing a site away from other plants or growing in containers sunk into the soil may be necessary to keep catnip from taking over the garden. Catnip can grow to 3 feet tall and spreads readily, so choose a site with plenty of room. Catnip attracts bees and butterflies, so you may wish to choose a site away from outdoor living areas if bees are a concern, or near a vegetable garden to attract pollinator insects. Some people find the odor of the catnip leaves slightly offensive, so choosing a site away from the main entrances and outdoor entertaining areas may be preferable.
Catnip can be grown from seed or from divisions of existing plants. The seeds are slow to germinate and should be started up to 10 weeks prior to the frost-free date. Although catnip tolerates light frost, the seedlings are more delicate and should not be transplanted until after the danger of frost has passed in the spring. In later years, catnip planted in the ground will likely emerge before the last frost and survive through early spring frosts.
Divide catnip as you would any perennial. Divisions and transplants can be planted in the garden any time from spring to early autumn
Catnip attracts cats, and some cats are even more sensitive to fresh, live catnip than the dried herb. Feral, stray or outdoor cats in the area are likely to find your catnip and may eat or roll in it. To avoid feline pruning and holes in the middle of the plant where cats have crushed it, protect the plants with fencing that cats can’t get through, under or over. Determined cats may come onto patios or porches with catnip and get into containers of the herb.