How to Grow Catnip Seeds
Grow Guide #2404
Binomial name: Nepeta cataria
Life Cycle: Perennial
This 'How to Grow' guide details everything a home gardener needs to know to plant, grow and care for Catnip (Nepeta cataria).
When to Sow Catnip Seeds
Catnip is a perennial plant that grows year round in most climates. Use the table below to identify the best time of year to sow catnip seeds in your climate.
Catnip plants are best grown in full sun. Choose a location that will receive at least 6 hours of full sun each day.
Catnip plants are perennial, meaning they live for several years. Choose a permanent position where plants can grow undisturbed by regular digging or other disturbance.
Catnip plants need a well drained soil enriched with plenty of organic matter. Prepare soil by weeding it thoroughly, digging it over to loosen it and adding aged animal manure or compost. Keep the area free of weeds until planting. Learn more about preparing soil for planting here.
Catnip plants can be grown in containers. If possible choose a variety that’s recommended for container growing. Use a good quality potting mix and make sure your container is large enough for mature plants; a minimum of 10 litres is recommended for catnip. During the growing season, keep in mind that container grown plants may need additional fertiliser to encourage healthy growth.
How to Sow Catnip Seeds
Catnip seeds do not require any treatment (eg soaking, stratification) before sowing.
Catnip seeds grow best when they are raised in trays or other containers and transplanted to the garden once established.
- Fill trays, punnets or jiffy pots with a good quality seed-raising mix, or use soil starter pellets.
- Sow seeds 5mm deep.
- Keep soil moist but never wet or dry.
- Seeds should germinate in around 10-20 days at a soil temperature of 21-27°C.
- Transplant seedlings to the garden once they have their first true leaves and are large enough to handle (usually 5-10cm tall).
- Plant out, spacing plants 60cm apart.
Optional: In cool climates catnip seeds can be sown indoors 6 weeks before the last expected frost. Grow them in a warm position with plenty of natural light.
How to Grow Catnip
Catnip plants may need watering during the growing season. Water when the soil is dry about 5cm below the surface (test this by scratching away a little soil with your finger). Water deeply in the early morning or late afternoon. Avoid watering the leaves of plants to avoid fungal diseases. Learn more about watering here.
Catnip plants will grow in nutrient-poor soils and do not need additional fertiliser during the growing season.
Deadhead catnip flowers regularly during the growing season. Using sharp secateurs or snips cut fading or dead flowers off just above a set of leaves. Removing old flowers regularly will encourage plants to produce more flowers. Learn more about deadheading flowering plants here.
When plants have finished flowering prune them back to neaten them and encourage strong new growth. Using sharp secateurs or snips, cut individual stems just above a set of lower leaves.
Catnip plants may die back in cold weather. Cut plants back just above ground level in late autumn, or prune off dead foliage when new leaves emerge in spring.
Common Problems when Growing Catnip
Like all plants, catnip is susceptible to some pests, diseases and other problems. Below is a list of the most common problems gardeners encounter when growing catnip plants:
- Aphids are small (2-4mm long) sap-sucking insects that congregate on the new shoots or the undersides of leaves. They can cause leaves to wilt or become discoloured, and also excrete honeydew which can attract ants and other insect pests. To manage aphids, remove them by spraying with a garden hose, apply a soap or alcohol spray, or encourage predatory insects to your garden. Read more about aphids here.
- Root rot is a disease caused by soil-borne fungi found in wet soil. Plants may be slow to establish, have yellowing or wilted foliage and have soft, brown tissue around the base of the stem and roots. Root rot is often fatal; remove and dispose of affected plants. Reducing soil moisture, adding organic matter to the soil and making sure mulch doesn't touch the stems of plants may help avoid root rot.
- Spider mites (Tetranychus urticae), also known as two spotted mites, are sap-sucking arachnids that cause dry, wilted or discoloured leaves. The undersides of leaves may feel dry and a little like fine sandpaper. Prune plants to allow good air flow or spray with eco-oil or wettable sulphur. Learn more about managing spider mites here.
- Thrips are black, beige or white flying insects (<1.5mm) with larvae that suck tissue from leaves and petals, leaving behind very small white or transparent markings. While not usually causing serious damage, the marks affect the look of flowers and foliage and thrips can also transfer pathogens from one plant to another. Wash thrips from affected plants using a garden hose, encourage predatory mites and lacewings with companion planting, or spray with soap, eco-oil or neem oil.
- Whitefly is a sap-sucking insect related to aphids. They are often found in large numbers on the underside of leaves and will swarm in clouds when disturbed. Plants may have yellowing leaves or may wilt, and growth will be slowed. Whitefly can be removed with a garden hose or sprayed with soap spray. Badly affected plants should be destroyed. Attracting beneficial insects that will prey on whitefly can be beneficial. Read more about managing whitefly here.