Nepeta
A classic, romantic, cottage-garden favourite, catmint is surprisingly robust, and possesses an essential quality for our times – drought-tolerance
PLANT PROFILE
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.
Clump-forming cultivar with a bushy, upright habit. Soft, hairy, greygreen leaves and dark stems give rise to palepink flowers from purplepink calyces in July and August. Good seedhead. 80cm x 70cm. RHS H7.
An attractive, entirely distinct, form introduced in the early 2000s by Jeff Hodson. Masses of long-lasting, dainty, pale-lilac/pink flowers from grey-blue, aromatic foliage. 60cm-1m x 60cm-1m. RHS H7.
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.
I started gardening in East Kent in the early 1990s, during a succession of hot, dry summers. While working for my local college as part of the grounds maintenance team, I discovered a plant that performed better the hotter and drier it got. When others around it struggled, it sang through the summer with tussocks of woolly, grey-green foliage that seemed to become silver as temperatures rose and a haze of purple/mauve flowers; it was Nepeta x faassenii, a hardy, herbaceous perennial, roughly 30cm x 50cm. It softened the straight lines of the path edges in the cottage gardens of the college grounds. Stubbornly determined to grow in what felt like a hostile situation for any plant, it rarely failed to impress me – in short, the genus Nepeta got stuck in my psyche early on as a gardener.
In the coming years, as I honed my gardening skills and my plant knowledge grew, I came to rely on the qualities of Nepeta. They are astonishingly tough plants for what I and many others see as a classic, romantic, cottage-garden plant. 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.
More recently, from 2018 to 2021, I took part in the RHS Nepeta trial, of 123 species and cultivars. It looked for overall impact from the plant, length of flowering, quality of the flowers and foliage, and resistance to weather. National Collection holder Fi Reddaway provided many plants for the trial, and helped point out subtle differences between plants, such as how the colour of many cultivars’ calyces supports the quality and tone of flower colours.
The early flowering Nepeta ‘Hill Grounds’, like many nepetas we see in the UK gardens, is of mixed parentage. With deep-violet f lowers and mounds of grey leaves measuring about 50cm x 70cm, it is a great plant for infilling among other perennials. For me, the best recent find is Nepeta racemosa ‘Amelia’, which I bought from Claire Austin and which will hold its own against any plant in a mixed perennial border. There are few pink nepetas and this one is distinct, with dusty, lilac-pink f lowers on a strong plant and small, grey-blue leaves rarely fails to impress; it got stuck in my psyche early on in my about 80cm x 80cm. If you are looking for a pink form with good seedheads, N. grandilora ‘Dawn to Dusk’, introduced by Dutch nurseryman Coen Jansen, is what you need. So good are the seedheads that I used them in my Chelsea Gold medal-winning display of seedheads in 2019, and it is not alone if you are gardening career looking for winter structure as well as summer beauty. Both the wondrous N. cyanea, which has green foliage and stout, terminal spikes of deep, lilac-blue f lowers more reminiscent of agastache than nepeta, and N. subsessilis ‘Washfield’, with its whorls of terminal f lowers and glowing autumn foliage, have great seedheads. Both also prefer moist (not waterlogged) soils in semishade and are perfect for the borders that only get sun for part of the day.
Introduced in the 1980s, this popular cultivar was named Perennial of the Year in 2007 by the US Perennial Plant Association. Small, blue-purple flowers for most of the summer. 60cm x 60cm. AGM. RHS H7, USDA 4a-8b.
From the Caucasus. Sturdy square stems with large, terminal, lilac-blue flowers; a robust perennial for part shade. Can tolerate sun if grown in damp soil. Great autumn leaf colour and excellent seedheads that last well into the winter. 70cm-1m x 50cm. RHS H7.
If space is limited or you want good succession from your borders, N. 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. N. 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 f lowers in July.
If you are a water-conscious gardener, Nepeta is invaluable; when I was head gardener in a dry, coastal garden, I came to rely on its drought-tolerant qualities. I once needed a skirt at the feet of Rosa ‘Mrs Oakley Fisher’, a hybrid tea with a simple flower from May to November. It was planted in a narrow border in poor, flinty soil, with sun-drenched walls and paths around it. I settled on N. racemosa ‘Walker’s Low’, a deceptively named cultivar that reaches to 80cm or so.
Its job was to unify and soften the border, and it had to work as hard as the rose above it. What a great choice it turned out to be, not only romantically softening the border edge but repeat-flowering all summer with little attention while also ref lecting some of the sun’s rays away from the roots of the rose, helping to cool the soil and keep weeds at bay.
Steve Edney is a member of the RHS Herbaceous Plant Committee.
Introduced by Clarence Elliot in 1935 and named after his nursery, Six Hills. Deservedly popular border plant, vigorous and bushy with small, grey leaves and lavender-blue flowers. 1m x 90cm. AGM. RHS H7, USDA 4a-7b.
The flowers of this cultivar are said to be a truer blue than is typical of most other nepetas. It has a long flowering season and handsome, silvery-grey foliage. 50cm x 50cm. RHS H7, USDA 3a-8b.
Bred by the late Janet Cropley from a seedling found in her Northamptonshire garden, Hill Grounds. Deep violet-blue flowers, darker than those of most nepetas, from June. 50cm x 70cm. RHS H7.
A bushy form with intense blue flowers and purple calcyes held well above the foliage. A bee magnet, it was introduced by Avondale Nursery but may originate from Chettle House in Dorset. 70cm x 40cm. RHS H7.
*Holds an Award of Garden Merit from the Royal Horticultural Society. †Hardiness ratings given where available.
How to grow Nepeta
• Species of Nepeta, such as N. racemosa, N. x faassenii and N. grandiflora and the garden hybrids that come from them, seem to thrive on neglect and are best grown in nutrient-poor, light soils. 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. They need full sun and a welldrained soil to be at their best. Drainage is particularly important in winter, as they can succumb to too much wet.
• 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 N. 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. You can take stem-tip cuttings in early spring, or from fresh growth after the summer cut-back. Sow fresh seed in spring.
• N. 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.
• N. subsessilis from Japan and N. 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.
WHERE TO SEE AND BUY
• Beth Chatto’s Nursery Clacton Road, Elmstead Market, Elmstead, Colchester, Essex CO7 7DB. Tel 01206 822007, bethchatto.co.uk
• Claire Austin Hardy Plants White Hopton Farm, Wern Lane Sarn, Newtown, Powys SY16 4EN. Tel 01686 670342, claireaustin-hardyplants.co.uk
• Hardy’s Cottage Garden Plants Priory Lane Nursery, Freefolk Priors, Whitchurch, Hampshire RG28 7FA. Tel 01256 896533, hardysplants.co.uk
• Fi Reddaway* South Zeal, nr Okehampton, Devon E20 2JS. Open as part of the South Zeal and District Open Gardens Day, 19 June, 10am-4pm. £4 for entry to all participating gardens.
*National Collection holder.