Catnip (Nepeta cataria) is a hardy perennial herb in the mint family, prized for both its ornamental appeal and its well-known effect on cats. It typically grows 60–90 cm tall, producing soft, heart-shaped leaves with serrated edges and a covering of fine silver-grey hairs that give the plant a slightly downy appearance.

During summer, catnip produces attractive spikes of small white to pale lavender flowers dotted with purple spots, which are highly attractive to bees, butterflies, and other beneficial pollinators. This makes it a valuable addition to any herb or kitchen garden beyond its novelty value.

Catnip contains an essential oil called nepetalactone, which triggers a temporary euphoric behavioural response in many cats — rolling, rubbing, purring, and playful excitement — though approximately one-third of cats are genetically insensitive to it.

For humans, catnip has a long tradition in herbal medicine. Leaves and flowers are used to brew a mild, pleasantly aromatic tea traditionally associated with relaxation, mild sedation, and digestive comfort. The leaves can also be used fresh in salads or as a general culinary herb.

Catnip is adaptable, easy to grow, and thrives in well-drained soil with good sun. It can self-seed prolifically if not managed, and gardeners may need to protect young plants from enthusiastic feline visitors.

How To Grow

Growing Catnip

Catnip is a vigorous, low-maintenance perennial herb that rewards even novice gardeners. Once established it largely looks after itself.

Starting from Seed

• Sow seeds indoors 6–8 weeks before the last expected frost, or direct sow outdoors in spring once the soil has warmed.
• Press seeds lightly onto the surface and cover with no more than 3–5 mm of fine compost — catnip needs light to germinate well.
• Keep the growing medium moist but not waterlogged at 18–24°C. Germination typically takes 1–3 weeks.
• Thin seedlings to 45 cm apart once they have two true leaves.

Starting from Transplants or Division

• Plant out after any frost risk has passed, spacing plants 45 cm apart in all directions.
• Established plants can be divided in spring or autumn to create new plants.

Soil and Position

• Prefers well-drained or even poor, rocky soil — rich soils can cause lush but less aromatic growth.
• Full sun produces the most aromatic foliage, though partial shade is tolerated.

Watering

• Water regularly until established. Once mature, catnip is highly drought-tolerant; water only when the soil is completely dry.

Ongoing Care

• Cut back stems by half after the first flush of flowers to encourage a second flush and prevent legginess.
• Deadhead regularly to reduce excessive self-seeding, as catnip can spread readily.
• Containment: Consider growing in pots or raised beds to restrict spreading.
• Cat protection: Young plants may need a wire cage or netting until they become sturdy enough to withstand feline attention.

Harvesting

Harvesting Catnip

When to Harvest

• Begin harvesting once plants are well established, typically from mid-summer onwards.
• For the strongest aroma and highest nepetalactone content, harvest just as the first flower buds appear but before they fully open.
• Harvest in the early morning after dew has dried but before the heat of the day volatilises the essential oils.
• Established plants can yield two or more cuts per season — once in early summer and again after the plant regrows following the first cut.

How to Cut

• Use clean, sharp scissors or pruning shears.
• Cut stem tips of 10–15 cm, or cut whole branches back by two-thirds, always leaving at least one-third of the plant intact to allow vigorous regrowth.
• Avoid cutting into old, woody base stems.

Drying

Drying concentrates the oils and extends shelf life significantly:

• Air drying: Bundle 6–12 stems, tie with string, and hang upside down in a warm, dark, well-ventilated location for 1–2 weeks. Alternatively, spread stems on a mesh rack.
• Dehydrator: Place stems in a single layer and dry at the lowest heat setting (35–40°C) until completely crisp.

Storing

• Strip dried leaves and flowers from stems and store in airtight glass jars away from light and heat.
• Label with the harvest date. For peak potency, use within 6–12 months.

Using Fresh Catnip

• Fresh sprigs can be given directly to cats or used to brew herbal tea. Fresh catnip has a milder aroma than dried.

Common Problems

Common Problems with Catnip

Pests

• Aphids: Soft-bodied insects that cluster on new growth and flower stems, causing distortion and sticky honeydew residue. Blast off with a strong jet of water or apply an insecticidal soap spray. Encourage natural predators such as ladybirds and lacewings.
• Spider mites: More common in hot, dry conditions. Fine webbing on undersides of leaves is a tell-tale sign. Increase humidity around plants and treat with neem oil or insecticidal soap.
• Whitefly: Can colonise plants in sheltered or warm conditions. Yellow sticky traps and insecticidal soap are effective controls.
• Cats: The most notorious 'pest' of catnip. Cats may roll on, dig up, or entirely flatten young plants. Protect seedlings with wire cloches or mesh cages until plants are large and sturdy enough to survive feline attention.

Diseases

• Powdery mildew: A white, powdery fungal coating on leaves, most common in dry conditions with poor air circulation. Improve spacing, remove affected leaves, and apply a dilute baking soda solution or a fungicide approved for edible herbs.
• Root rot: Caused by overwatering or poorly drained soil. Catnip is far more susceptible to wet conditions than drought. Ensure excellent drainage and reduce watering frequency.

Other Issues

• Legginess: Caused by insufficient light or failure to prune. Cut back after flowering to keep plants bushy and productive.
• Invasive spreading: Catnip self-seeds prolifically. Deadhead spent flowers promptly to prevent unwanted spread throughout the garden.