Pulmonarias: Common, but rather special too

Soldiers and sailors. Joseph and Mary. Spotted dog. Jerusalem cowslip. Lungwort. When a plant has so many common names (and these are just a few) you know that it has been widely grown and much admired. These names refer to the genus pulmonaria, which has been grown in British gardens for centuries. Its charm lies partly in its early flowers, most of which start pink and fade to blue, and also in the almost infinite variety of its foliage – plain green, mottled, speckled, splashed and silvered. Pulmonarias are also robust, reliable and easy to grow.

Pulmonarias are promiscuous plants that self-pollinate and hybridise. As a result, there are far too many named cultivars, often with little to tell them apart. This similarity extends to plants in the wild, and botanists disagree about how many species exist, with the number varying between a dozen and 18. All are found in Europe and parts of Asia, where they grow on the edges of deciduous woodland.

A sign of spring

All pulmonarias flower early in the year before their leaves appear. Although there are usually some remnants of the previous year’s foliage evident when the plants begin to flower, the new foliage starts into growth as the flowers die back. The flower stems usually have small leaves attached but these are not typical of the main flush of foliage that follows.

The first to flower (in December if the weather is mild) are the Pulmonaria rubra cultivars. These differ from most other species in having plain green, rounded leaves and flowers that do not change colour, remaining coral-red throughout their lives. Pulmonaria rubra 'David Ward’, a cultivar introduced by Beth Chatto, has white-edged leaves. The leaves scorch in the sun and the wind, but if you can find a shady, sheltered place for it, this is a beautiful plant.

Pulmonaria longifolia has the long, narrow leaves usually associated with the genus. (One wild form found in southern France, P. longifolia subsp. cevennensis, has leaves about 18in long.) P. longifolia will grow in sunnier situations than other pulmonarias; dozens of selections have been made from this species. For me the best is P. longifolia 'Ankum’, which has a dome of bright blue flowers.

The best blue pulmonarias tend to come from the P. angustifolia cultivars. Plants in this group tend to have unmarked, dark green foliage and purple-blue flowers. 'Blue Ensign’ has the darkest blue flowers of any pulmonaria.

The old cottage-garden plant is P. officinalis, with coarse, hairy leaves and pale pink and blue flowers. It’s vigorous and floriferous, but susceptible to mildew, so most of its old cultivars have been superseded by healthier hybrids.

Until modern plant breeders started to work on the genus, the pulmonarias with the most captivating foliage were cultivars and hybrids of P. saccharata. The leaves tend to be small and rounded with regular silver or pale green markings. P. saccharata 'Dora Bielefeld’ has rose-pink flowers and apple-green leaves spotted with grey.

Live and let grow

I have planted lots of pulmonarias among hellebores and spring-flowering bulbs under hazels. I’ve left them alone for years, and now have no idea what any of them are. The labels are faded and there are seedlings everywhere, even under a walnut tree where conventional wisdom has it that nothing will grow. If you want to keep your plants pure and true, cut the flowers as soon as they are over, before they set seed. I’m happy with my carpet of green, grey and silver leaves covered with spots, speckles and splodges and dotted with pink and blue jewels.

Breeding work

Until recently new pulmonaria hybrids have been the result of keen-eyed gardeners spotting an interesting seedling and propagating it. Vita Sackville-West, for example, found P. 'Sissinghurst White’ in her garden.

A new generation of plant breeders has turned its attention to the genus. In France, Didier Willery introduced P. 'Majesté’, whose silver leaves inspired others to produce plants with similar foliage.

The most extensive breeding of pulmonarias has been done at Terra Nova in the United States by plantsman Dan Heims. In the past decade, Heims has introduced a dozen cultivars. The plants cover the range of pulmonaria forms from the silvered leaves and white flowers of 'Moonshine’ to others with speckled foliage and cobalt-blue flowers, such as 'Trevi Fountain’.

John Hoyland is a plantsman, writer and owner of Pioneer Nurseries, Letchworth, Herts.

Cultivation tips

For pulmonarias to thrive, they need cool, moist growing conditions, preferably in dappled shade. They will not grow well in dry, baked soil.

When you first plant them, dig as much leaf mould or compost as you can into the planting hole and water them well for the first few weeks. If you have leaf mould, mulch around the crown of the plant each year.

Mildew can be a problem in summer. This is usually a sign that the plant is too dry. If it happens every year it probably means you are trying to grow pulmonarias in the wrong place.

Try improving the soil or move them somewhere damper. Cutting off diseased foliage (use shears and cut to the ground) encourages fresh leaves.

Burn the leaves you cut away – don’t put them on the compost heap. 'Blue Ensign’ always seems to get mildew, no matter how well it is grown. Live with it or cut back the affected leaves in the summer.

Cut back with shears in early winter, before the new flower stems start to grow. Getting rid of the previous year’s foliage is the most effective way of tidying the plant. Use shears because the leaves tend to have a central vein that is too strong to be cleared away by hand, as you would the dead foliage of other perennials.

In brief

WHAT

Genus of between 12 and 18 species of perennials, some evergreen.

SIZE

Low-growing – 6in to 18in tall.

CONDITIONS

Most prefer full or partial shade, in moist, humus-rich soil.

SEASON

Some forms bloom from December, but most in late winter and spring. The distinctive foliage is a feature in summer.

ORIGINS

Europe and Asia, in diverse habitats including mountainsides and woodlands.

Where to buy

Vanessa Cook at Stillingfleet Lodge near York has probably the largest collection of pulmonarias in Britain and most can be seen in her garden and nursery. Stewart Lane, Stillingfleet, York YO19 6HP (01904 728506; www.stillingfleetlodgenurseries.co.uk).

Beth Chatto Gardens and Nursery grows and sells good-quality pulmonarias. Elmstead Market, Colchester, Essex CO7 7DB (01206 822007; www.bethchatto.co.uk).

Thanks to Stillingfleet Lodge Nurseries, where the pictures were taken.

Taken from the March issue of Gardens Illustrated. Try three issues for £3 when you subscribe. To order call 0844 844 0260 and quote GITEL211 or visit www.bbcsubscriptions.com/gardensillustrated and quote GITEL211. Offer ends 1 April 2011, UK direct debit only, terms and conditions apply.