Nepeta: how to grow and prune, plus 13 of the best varieties

By Jason Ingram

Published: Wednesday, 11 May 2022 at 12:00 am

Soft mounds of dreamy, grey-green foliage lightly fragranced when crushed; purple/lilac flowers adored by bees and butterflies; the ability to grow in some of the hottest, toughest spots – these characteristics make Nepeta a common and deserved addition to any garden despite only recently being trialled for garden worthiness by the RHS.

Nepeta has about 250 species scattered throughout Europe, Africa and Asia. It belongs to the Lamiaceae family, which is a bit of a heavyweight in gardening terms as it also contains garden favourites such as salvias, lavender and phlomis.

IN BRIEF

What A member of the Lamiaceae family, commonly known as catnip or catmint.

Origins Wild species are native across Europe, Asia and Africa. Many plants are species crosses and only known in garden cultivation.

Season Late spring to late summer.

Size Ranging from 15cm to 1.5m high, often with a width to match.

Conditions Most grow in full sun in well-drained soil, either alkaline or acidic. Some are tolerant of semi-shade and can grow in damper soils.

Hardiness Generally RHS H7, USDA 3a-8b.

If space is limited or you want good succession from your borders, Nepeta nuda and its cultivars are the right choice. They rocket out of the ground, occupying the vertical without using much of the horizontal, just what is needed for a change in form in many garden borders. Nor do they mind mixing in with other plants such as geraniums, rosemary and peonies. Nepeta nuda ‘Romany Dusk’ is my favourite. It has strong, deep-purple stems up to 1.5m, making it attractive even as it builds to flowering on branching stems, clothing the plant with violet-blue flowers in July.

How to grow Nepeta

Where to grow Nepeta

Species of Nepeta, such as Nepeta racemosa, Nepeta x faassenii and Nepeta grandiflora and the garden hybrids that come from them, seem to thrive on neglect and are best grown in nutrient-poor, light soils. They need full sun and a well-drained soil to be at their best. Drainage is particularly important in winter, as they can succumb to too much wet.

How to care for Nepeta

Avoid overfeeding or overwatering them, or else their soft, silky foliage will be too much for the thin, square stems to bear and they will flop. This is often the case when they are grown on richer loam or clay soils.

How to prune Nepeta

A hard cut-back straight after flowering is often necessary to keep plants from opening up in the middle. On dry silt or sandy soil it is best to just deadhead, otherwise the plant may struggle to reflower. During the RHS trial, each of the three plants of each cultivar being grown would be pruned differently: one would be left untouched, one would be deadheaded and one would be cut to the ground after flowering. It was noted that many of the Nepeta racemosa cultivars often opened up in the centre leaving a skirt of flowers at the edge, which was infilled with new foliage and flowers without any pruning, covering the old flowers at the edge in so doing – making it useful for low-maintenance planting schemes.

Clump-forming species need dividing regularly, leaving the clumps no longer than three years for best results and to keep the group vigorous and healthy.

How to take Nepeta cuttings

You can take stem-tip cuttings in early spring, or from fresh growth after the summer cut-back. Sow fresh seed in spring.

Caring for other varieties of Nepeta

Nepeta nuda and its cultivars seem content on almost any soil pH. There is no need to cut them back after flowering as they do not reflower. Stem-tip cuttings of cultivar types in early spring is the best way to increase numbers. Seed is viable and easy from spring surface-sowing in a seed tray, although there is some variability in the quality of the seed-raised offspring.

Nepeta subsessilis from Japan and Nepeta cyanea from the Caucasus form a handful of exceptions in the Nepeta tribe, preferring cool, damp spots in partial shade, although I have noticed over the years that they can cope with sun if they have a moist soil. Their serrated, green leaves turn autumnal hues of orange and yellow, while the seedheads of these species are worth leaving for extra interest in winter. I have had great success with cuttings taken from them in spring while the stems are short and before they hollow out in the centre in summer.