Catnip grows 40 to 90 cm tall, flowers from June to September and smells strongly of mint when you rub a leaf. It tolerates drought, copes with poor soil and draws bumblebees all summer. What confuses most people is that two different plants are sold under almost the same name, and only one of them makes a cat behave oddly.
Two species, one reaction
| Catnip | Catmint | |
|---|---|---|
| Species | Nepeta cataria | Nepeta faassenii and relatives |
| Height | 40 to 90 cm | 25 to 50 cm |
| Flower colour | White to pale pink | Blue violet |
| Leaves | Grey green and heart shaped | Grey and narrow |
| Cats | React clearly | React weakly or not at all |
| Used for | Tea, herb garden, cat toys | Border edging and ground cover |
The compound that triggers the reaction is called nepetalactone, and the level is considerably higher in Nepeta cataria. If you buy a plant labelled only nepeta at a garden centre, it is almost always the blue flowered border plant.
Why only some cats react
About two thirds of all cats react to catnip. The trait is inherited, and a cat without the gene will never care, however much of it you grow.
Kittens do not react. The response only appears at three to six months of age.
The effect is short. Five to fifteen minutes, then it fades.
Then comes a pause. The cat will not react again for one to two hours, no matter how much catnip is left.
It does no harm. The cat may go limp or boisterous, but the compound is not addictive.
Sowing catnip
The seed needs light to germinate. Scatter it on the surface of moist seed compost and press it down, do not cover it.
Sow indoors from February to April at 18 to 22 degrees.
Germination takes 7 to 14 days.
Prick out at two true leaves and harden the plants off before planting out.
Plant out in late May with 30 to 40 cm between plants.
Direct sowing in place in May works but gives flowers only in the second year.
Site and soil
Full sun and free draining soil, preferably with some lime in it. Catnip takes drought once established and does not want to stand wet over winter. Wet clay in November is what kills most plants.
Feed sparingly. Plenty of nitrogen gives floppy stems that fall over in rain.
Cut back after the first flowering
This is the move that doubles the flowering and the one most often left out.
When the first flush starts to fade in late June or early July, cut the whole plant back to 10 to 15 cm. Water it and leave it alone. After three to four weeks new foliage comes, and the plant flowers a second time in August and September.
Without the cut back, the plant stands brown and setting seed for two months.
Protect young plants from the cat
A cat that finds a newly planted catnip will roll on it until it is flat. That is the most common reason the plant disappears in its first year.
Put a wire cloche or a bell jar over the plant for the first season. Once the root system is established, the plant recovers even after fairly rough treatment.
Harvest and tea
Harvest the top third of the shoots just as flowering begins. That is when the level of aromatic compounds is highest.
Tie loose bunches and hang them in shade in an airy place. After two weeks the leaves are dry and can be crumbled into a jar. A couple of teaspoons of dried leaf in a cup of hot water gives a mild mint tea. The taste is softer and a little more herbal than peppermint.
If you want the classic mint in the cup instead, see the article on mint. More herbs to sow are among our herb seeds.
About the mosquito claim
Nepetalactone has been shown in laboratory trials to repel mosquitoes. That usually turns into the claim that a catnip plant in the border keeps mosquitoes away, and it does not work like that. The effect requires the compound to be applied to the skin in concentrated form.
The plant does do real good for bumblebees and honeybees, which visit it from June until the frosts. More species like that are in the article on how to create a butterfly garden.
It sows itself
Nepeta cataria sets seed freely and spreads across the border if you let it. Cut the flower stems off before the seed ripens, which is what the July cut back does anyway.
The plant lives three to five years and should be divided or replaced after that. More perennials that take the same dry position are in the article on perennials.
Author: Emma Vogiatzi
Fact-checked by Erik Hoekstra
Last updated 2026-08-31