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Plant Notebook
Summer Perennials

Our regular update on our Plants selected for each season - here perennials that will add late summer colour to your garden and maintain interest in autumn.

See the index below for more specialist pages and plant features

Nepeta faassenii
Nepeta faassenii
Nepeta mussinii

Catmint, Nepeta mussinii, is one of the well-known stalwarts of the perennial garden, although the plant we usually buy is actually N. faassenii. Aromatic grey foliage on a bushy, clump forming plant, develops into long spikes of lilac- purple flowers to 45cm (18in) that last over several weeks. Look for N. faassenii ‘Six Hills Giant’ and ‘Walker’s Blue’. In mid-summer, after they have finished flowering, a hard cutback encourages a second burst of bloom.

Great in the front of the order where the flowers sweep the paving (not so great over mown lawns where they can be easily shorn). Other taller catmints, such as N. gigantea, can be used further in the border. N. racemosa (syn. N. mussinii) ‘Walker’s Low’ is also invaluable, as well as less attractive to cats, growing to 30cm or so (1ft) and lavender-blue flowers. Planting young plants or direct sowing can also foil cats – planting large new bushes seems to be the ultimate draw-card for felines.
Cultivation Well drained, good soils in full sun. Pinch back in early spring to keep compact. Cut back hard after flowering finishes to encourage a second crop of flowers. Divide every few years to rejuvenate old, woody plants it they become open in the centre.
Propagation Division, cuttings in late spring, seed

Hemerocallis (Day Lilies)
H. '18 carat'
Hemerocallis '18 carat'

Hemerocallis '18 Carat' is a beautiful clear yellow daylily that will brighten your summer border and quickly form a substantial clump. Semi-evergreen or evergreen grassy foliage ranges from minature to giants- make sure you know the eventual size of your plant and, as there are literally thousands of varieties, try to see them in flower before you buy!
Sources Hemerocallis are widely available, for named some cultivars see specialist nurseries
Sources Widely available
Cultivation Position carefully as most turn their flowers to the sun. Plant in a good soil that does not dry out. Watch for slugs or snail damage in spring, can also suffer from spider mites and aphids. Divide regularly as flowering is poor on congested plants
Propagation Division in autumn or spring, seed (although plants will not come true to type)

H. 'Kent's Favourite'
Hemerocallis 'Kent's Favourite'

Centurea montana
Centurea montana

Blue is always welcome, and the unusual clear blue thistle-like flowers of the perennial cornflower are carried above the foliage all summer. A spreading mat of creeping rhizomes, with grey-green foliage this is a plant that plays a great supporting role in any planting scheme. Good at the front of the border where the evergreen foliage is useful in winter. Also available are white and pink forms (C. montana 'Alba' and 'Carnea')
Sources Widely available
Cultivation Deadheading will encourage a longer flowering season. Tolerant of dry conditions, centurea is quite hardy and suited to both coastal and colder climates. Divide when the plant becomes open and woody in the center.
Propagation Division

Gaura lindheimeri 'Whirling Butterflies'
Long flowering Gaura lindheimeri 'Whirling Butterflies'

Long flowering Gaura lindheimeri is a must for its lovely dancing butterfly flowers from summer until the frosts.
Sources Widely available
CultivationTolerant of quite dry conditions and a light soil, gaura needs full sun and grows to 1.2m(4 ft). Trim back early each spring to prevent it from sprawling.
Propagation Cuttings

Geranium himalayense
Geranium himalayense

(Syn. G. grandliflorum) This is one of the best perennial gernaniums. It forms clumps of largish neatly cut leaves 45cmhigh and wider. In early summer deep violetblue flowers stand above the folaige creating a haze of colour.
Sources Widely available
Cultivation Frost hardy, G. himalayense needs a sunny position with a welldrained but moist soil.
Propagation Divide and transplant in winter when dormant only as resents disturbance, may take time to recover from division.

Astrantia 'Ruby Wedding'
Astrantia'Ruby Wedding'

The deeply lobed leaves form clumps and long stems carry heads of tiny flowers encircled by a ruff of pointed bracts, like and Elizabethan collar. The species, Astrantia major has soft pink or white flowers. ‘Ruby Wedding’ is a named form that has deep red flower bracts, as has ‘Hadspen Blood’; ‘Rosea’ is pink and on‘Sunningdale Variegated’ the leaves are splashed with yellow.
Astrantias are shade lovers, ideal for lighting up corners and borders with only partial sun, similar to their woodland or streamside homes. These plants need lots of constant moisture to withstand the glare of the New Zealand sun.
Sources Astrantia are widely available, go to a specialist for named cultivars such as 'Ruby Wedding'
Cultivation Grow in moist, humus rich soils in partial shade. Cut-down dead growth in late winter. Divide only when they outgrow their position.
Propagation Division in spring, seed

Paeonia lactiflora 'Albert Crousse'
Paeonia lactiflora 'Albert Crousse'

Paeonies are one of the glories of the summer border. A profile of paeonies, varieties suited to warmer gardens, cultivation and propagations.

Papaver orientale
Papaver orientale

The stunning, exotic flowers of the oriental poppy make it a favourite in the perennial garden. Nodding, hanging buds turn upwards as they open into richly textured flowers with a dark blotch at the centre. Oriental poppies come in colours from pure white to pink, coral, true reds and even startling orange. The leaves are hairy,long and grey-green and grow in a central rosette.

Oriental poppies dislike being moved so plant them young and leave them be, lifting only to divide them when old and flowering becomes poor.
Sources Widely available
Cultivation Good, humus rich garden soils that are well-drained but don’t dry out. Plant in full sun.
Propagation Seeds in spring or autumn; root cuttings

Kniphofia 'Little Maid'


Plants that demand a second look, many kniphofia flower over a long season, others are spring or autumn flowering.

More on Kniphofia

Scabiosa caucasia
Scabiosa caucasia

Scabious, the pincushion flowers, are an amazing sky-blue, or pink-mauve or lilac depending on your soil and the particular plant - they do vary!

Reaching 45-60 cm (18-24in) it will flower continuously if you dead-head it, adding a vaulable touch of soft blue to a planting scheme and a light and airy look with its rounded, flat-ish flowers.

There is a white form. Scabiosa c. 'Mrs Isaac House' and S. columbaria is a lower (60cm/25in) form, look for 'Butterfly Blue'.
Sources Widely available
Cultivation most well-drained soils, that tend to the alkaline. Plant in full sun, it handles dry conditions well. Dead-head to encourage re-flowering.
PropagationDivision, seed

Campanula persicifolia

Campanula persicifolia

The large nodding bells of Campanula persicifolia make it a charming cottage garden plant, and is also at home in more formal gardens. The plant forms a rosette of narrow green leaves, and the flower stems can reach up to 1 metre. An easy perennial, it can spread quite vigorously and (even ramp away) when happy so take care not to plant next to your most precious darlings! There are both blue and white forms, some named.
Sources Widely available
Cultivation Prefers a moderately rich soil that is moist and well drained. Plant in sun but away from strong winds that can flatten the tall stems. Dead head regularly to prolong flowering and divide every 2- to 3-years to rejuvenate the plant. Watch for slugs in spring.
Propagation Division in spring or autumn, seed.


Invaluable arctotis, long flowering and brilliant colour on low green or grey-green spreading mats of leaves. Easy to keep within bounds and hardly ever be out of flower. Especially good on the coast.
Sources Widely available
Cultivation Most well drained soils in a warm and sunny position, tolerates light soils and dry climates. Grows to 45cm (18 in). Frost tender; in cold areas grow as annual bedding plant and take cuttings each autumn.
Propagation Cuttings

Geum montanum
Geum montanum

Geum montanum forms attractive clumps and flowers all summer long. A good edging plant and a grouping will provide a low in-fill in planting schemes.
Sources Widely available
Cultivation Most soils in sun or part shade. Deadhead to lengthen the flowering season. Grows to 10cm (6in)
Propagation Division

Penstemon 'Garnet'

Spikes of hanging flowers, almost foxglove-like, in a range of brilliant colours (some with a white lip), make penstemons a valuable player in the plant repertoire. Developing into large clumps, most about 60cm (2ft) tall, penstemons have evergreen foliage and they are tough, enjoying both full sun and partial shade, and extremely long-flowering. There are many species that withstand the rigours of hot dry summers and extreme winter cold.

Penstemon ‘Garnet’ is just one of many – deep purple ‘Stapleford Gem’ and ‘Purple Passion’, lilac 'Alice Hindley', soft pink ‘Hidcote Pink’, long flowering ‘Pennington Gem’ – there is a penstemon for almost any planting scheme.
Sources Readily available
Cultivation Plant in humus rich soil that is well drained, in full sun. Deadhead or cut back hard after flowering to encourage a second flush of bloom. Divide if they outgrow their space or become open, ceasing to flower in the centre.
Propagation Division in spring, cuttings of non-flowering shoots or seed sown in spring/autumn

More plant features

More Flowers

More flowersAlliums and bearded iris are key plants in the summer garden.

In late summer & autumn there are host of beauties to enjoy

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Last revised 25 Mar '03