Plant profile: Sanguisorba

Long flowering, hardy perennials that are easy to grow and perfect for adding an airy feel to borders

Once, while wandering over the chalk downs of Box Hill in Surrey, I noticed the delicate scent of cucumber. On inspection of the ground beneath my feet I discovered I was standing on a diminutive pinnate-leaved plant that had small, globular, greenish-red heads with long straggly stamens: the salad burnet ( Sanguisorba minor). This was my first encounter with one of the two British native burnets, the other, the great burnet ( Sanguisorba officinalis), preferring moisture-retentive soils in meadows or at the edge of woodland. It is much taller at 1.2m with small, burgundy bobbles atop wiry stems.

Burnets are found throughout Europe, Asia, Japan and North America. On a plant-hunting expedition to Korea in 1993 with James Compton, John d’Arcy, and John Coke, we collected several seed samples from various Sanguisorba species possibly akin to Sanguisorba officinalis and Sanguisorba tenuifolia among others. Their horticultural importance is that it appears that the further east the plant was collected the later the flowering time. In Europe, Sanguisorba officinalis usually blooms in late June and July, whereas our collections from Korea were at their peak in August and September. Sanguisorba ‘Cangshan Cranberry’, collected in Yunnan in southwest China by Dan Hinkley, flowers as late as October and November in some seasons. With the propensity for hybridisation within this genus many garden-worthy burnets have been named but in such large numbers that a trial to evaluate the many species and cultivars is currently being undertaken at RHS Garden Wisley.

Burnets are particularly suited to naturalistic plantings, and different hybrids flower throughout the season from late April to November. There are several methods of pollination within this genus. Sanguisorba minor and Sanguisorba tenuifolia var. alba are wind pollinated with long stamens so that pollen is easily wafted away in the breeze. These species and hybrids are rarely scented and tend to be greenish or white. Others, such as Sanguisorba officinalis with its compact burgundy burrs, are mainly pollinated by flies, while the fat catkins of Sanguisorba hakusanensis and its hybrids are sweetly scented and brightly coloured – the Barbara Cartlands of the plant world – in vivid pink or magenta that attracts butterfly pollinators in their native habitats.

As all species and hybrids readily hybridise these features get thoroughly mixed up in the resulting progeny. Growing several different burnets in close proximity has produced some wonderful hybrids such as those at Sussex Prairies where substantial specimens of Sanguisorba ‘Blackthorn’ with upright tapers of smoky pink flowers are cheek by jowl with other sanguisorbas and are likely parents to the Sussex Prairies hybrids: ‘ Sussex Prairies Cheyenne’, ‘ Sussex Prairies Navaho’, ‘Sussex Prairies Iroquois’ and ‘Sussex Prairies Apache’.

Sanguisorba canadensis is a robust plant with strong stems growing to 1.5m, and flowers in late summer with vertical candles of greenish-white opening to pure white as the flowers mature. How I would love to see a red or deep-burgundy flowered burnet with 15cm-long candles, such as those displayed by Sanguisorba canadensis, but with the propensity for hybridisation – watch this space.

Burnets are not all about flowers; their foliage contributes greatly to the naturalistic border with handsome pinnate foliage and toothed margins to the leaflets. Mounds of glaucous-green foliage on Sanguisorba armena are somewhat reminiscent of that of Melianthus major. White catkin-like flowers with black stamens, which are best removed as they detract from the foliage effect, appear late in the season. It spreads by suckering and can colonise large areas, whereas the well-behaved Sanguisorba obtusa ‘Chatto’ is compact with grey-green leaves.

Subtle and charming Sanguisorba species and hybrids grow easily in any moderately fertile soil that is moisture-retentive and does not get overly dry or waterlogged. They have excellent foliage, are not prone to pests and diseases and can provide many months of interest.

• Marina Christopher is a nurserywoman who runs Phoenix Perennial Plants.

Her recommendations for the best sanguisorbas can be found over the next five pages.

Sanguisorba ‘Blackthorn’ Smoky-pink candles atop robust, vertical stems. Flowers open in August remaining in good condition for weeks. A good parent for new hybrids as demonstrated by the Sussex Prairies tribe. 1.5m. USDA 4a-8b†.

Sanguisorba dodecandra This is a distinct species with sweetly scented, unusually yellowish-green catkins and long, white stamens emerging from luminous yellow buds. It has glaucous foliage, red-suffused stems and a running habit. 1m.

Sanguisorba ‘Autumn Red’ A robust, late-flowering cultivar with dark-red burrs. A great addition to the late summer border it will continue to flower right up until November and works well with tall grasses and perennials. 2.2m.

Sanguisorba tenuifolia ‘Stand Up Comedian’ With a graceful, slightly arching open habit, its clean, white catkins are held above glossy foliage and strong red stems. Bees and hoverflies are attracted to the flowers. 2.2m. Sanguisorba ‘Sussex Prairies Apache’ This upright hybrid, which probably has S. ‘Blackthorn’ as a parent, has large, rich-pink catkins that age to white with compact dense brightgreen foliage. 1.5m. Sanguisorba ‘Little Angel’ Prolific red buttons atop small, neat clumps of creamy white-margined foliage. Excellent for front of border or a container and not prone to reversion unlike other variegated cultivars. 30cm. Sanguisorba canadensis ‘Twisty’ A hybrid of S. canadensis with typical upright pristine white candles in late summer, and a distinctive bend in the flowering stem with striking red and yellow autumn foliage. 2m.

Sanguisorba ‘Burr Blanc’ Selected by Graham Gough of Marchants Hardy Plants in East Sussex, this hybrid seedling of S. tenuifolia var. parviflora has small, slightly nodding white burrs that stay in good condition for months. 1.2m. Sanguisorba tenuifolia ‘Purpurea’ Smoky-pink, upright elongated burrs appear in late summer on robust stems. It has fresh applegreen foliage and provides a strong vertical accent and a tidy habit. 1.5m. Sanguisorba officinalis ‘Korean Phoenix’ Vigorous and floriferous with slender stems, creating substantial clump It’s one of the seed samples (CDC 162) collected on the Korean expedition of 1993. 1.2m. Sanguisorba ‘Candy Floss’ Large, fluffy, pink catkins open on upright candles, which are sweetly scented and attractive to butterfly pollinators. Beautiful when dry, dishevelled when wet with fresh-green foliage and red stems. 1.5m.

Sanguisorba ‘Misbourne Pink’ An early flowering hybrid seedling selected by Sean Walter of the Plant Specialist nursery. It has abundant, elegant pink flowers and glossy foliage. 1.5m. USDA 4a-8b. Sanguisorba ‘Ivory Towers’ Early flowering in June, this hybrid has showy, nodding white catkins with black stamens. Discovered in a British nursery by Dutch nurseryman Coen Jansen. 1.2m.