Showy new growth and often abundant early-season flowers make Pieris an important addition to spring borders and other planting areas needing a flash of colour early in the year, but the plants' evergreen foliage and architectural habit also provide height, form and year-round interest to planting schemes.

This genus of seven species is originally a high-altitude plant from mountain ranges across southern and eastern Asia and eastern North America but they will thrive in the UK, given the right conditions.

Most Pieris cultivars are hybrids of two Asian species, P. japonica and P. formosa. The hanging cluster of white flowers give the common name lily-of-the-valley bush, although it is also known as andromeda and fetterbush.

As with other plants in the Ericaceae family, Pieris requires acidic to neutral conditions in order to thrive. Ericaceous composts can be added to intended planting sites to improve soil condition, and many growers report success with the addition of composted pine needles. However, these additives will dilute in the soil over time and will need regular topping up. In lime-rich areas, Pieris is perhaps best used in a container, where soil can be better managed.

This slow-growing genus offers a range of plant sizes - from small cultivars that rarely reach 1m and are ideal for planters, up to 6m giants that make great additions to shady woodland plantings. However, plants may take 20 years to reach their final heights.

Plants can become leggy, particularly if grown in overly moist soils, and there are mixed views on restoring plants. Some people see Pieris as a short-lived plant that needs replacing over time, while others will cut back hard in the hope of rejuvenating the plant, though this can have mixed results.

For the brave, it is a case of cut back hard, wait and see. Some plants will quickly put on a healthy show of new growth while others will fail to recover. Any hard pruning should be attempted after flowering, as new flowers appear on the previous season's growth.

But, given a good level of dappled shade and sufficient drainage, Pieris should remain bushy and compact with little need for pruning. Some shelter is required to protect new growth from extremes of sunlight and late frost.

The need for acid conditions makes this genus an ideal planting companion with Rhododendron, Azalea, Kalmia and Camellia, while its glossy foliage also makes a good backdrop to other spring-flowering plants including Forsythia, Kerria and Cytisus. Smaller varieties combine well with Erica, Calluna and spring bedding.

WHAT THE SPECIALISTS SAY

Lorraine Keets, nursery manager, Trehane Nursery, Dorset "Pieris makes for a very attractive specimen for a shady spot with acidic soil but, saying that, we are not selling as many as we were several years ago. It doesn't seem to be as fashionable as it once was.

"There are some large varieties out there like P. formosa that may put off people wanting to use the genus in smaller spaces, but there is something to suit most scales of design. P. japonica 'Little Heath' Award of Garden Merit (AGM) is a lovely, mounding form that reaches little over 1m in height.

"The genus is great in the spring, offering both vibrant new foliage and trusses of scented flowers. The larger P. 'Forest Flame' AGM and smaller P. japonica 'Little Heath' AGM give great new foliage. P. 'Flaming Silver' AGM offers a variegated leaf and P. japonica 'Valley Valentine' AGM offers deep-pink flowers instead of the usual white.

"Some may put on a second spurt of new growth later in the summer too."

Richard Burt, sales manager, Wyevale East Nurseries, Kent "Pieris is a great evergreen choice that will take a bit of shade and provide year-round interest. It has a long flowering season and, if you pick the right cultivar, you have the coloured spring foliage. There are variegated forms too.

"We've seen a lot of interest in P. japonica 'Purity' AGM of late. It has a basic green leaf but a real mass of pure white flowers. It's a difficult plant to get as a large specimen - a 20-litre form will be the largest that is readily available, with 7.5- and 15-litre options much more common.

"They are slow to grow, which is a good selling point - they will sit well in both small spaces and containers without outgrowing their space. They will need acidic soil and they should be planted away from the morning sun, particularly varieties like P. 'Forest Flame' AGM, whose new red foliage can be scorched after a frosty night."

IN PRACTICE

Trevor Tooth, garden designer, Kent "I have mixed feelings about Pieris as I know so many clients and friends that have bought and lost them but are compelled to continue replacing them.

"The Japanese andromeda (P. japonica) is a plant of great use in a garden with well-drained acidic or loamy soil and, in my experience, thrives in partial shade in a woodland glade situation.

"Although books say sun to shade, I find that at each end of the spectrum they tend to defoliate, struggle and go bare and woody. If there is one thing you want from this plant it is its striking, fiery foliage followed by flowers.

"So, in general, I use it in pot displays and recommend P. japonica 'Mountain Fire' AGM, my favourite variety."

SPECIES AND CULTIVARS

P. 'Firecrest' Award of Garden Merit (AGM) features heavy clusters of white flowers from late winter into spring. It is a green-leafed form enhanced with vibrant red new growth.

P. 'Flaming Silver' AGM is a decorative form with variegated foliage, enhanced each spring with golden-red new growth. A compact form, it rarely reaches 2m. It flowers from April.

P. 'Forest Flame' AGM displays pink and red young growth against dark-green old foliage and clusters of hanging, white flowers.

P. floribunda is a rounded shrub of average height and spread of 1.2m. New foliage appears yellow and matures to dark green. Upright, white flower clusters appear in April.

P. formosa reaches 6m in height and is a large white-flowered form.

P. formosa var. forrestii can reach over 5m in height. Vibrant red leaves emerge over dark-green foliage in March and April, followed by large trusses of white flowers in May.

P. formosa var. forrestii 'Wakehurst' AGM is a smaller cultivar of the species, to 3m.

P. japonica, which is also known as the lily-of-the-valley bush, grows to around 4m.

P. japonica 'Blush' AGM is a pink-flowered form with blooms appearing in May.

P. japonica 'Cavatine' AGM, a dense, compact form, reaches around 50cm. Upright clusters of white flowers appear in late winter.

P. japonica 'Compacta' features fragrant, white blooms in spring. It is a heavy-flowering dwarf form.

P. japonica 'Debutante' AGM is a small, rounded variety with long leaves and arching clusters of white flowers in spring. It will eventually reach 2m in height.

P. japonica 'Grayswood' AGM has bronze-green new shoots that turn to dark green. White flowers appear from pink buds in spring. It reaches up to 1.5m in height.

P. japonica 'Katsura' is a recent Japanese-bred variety, with wine-red new foliage maturing to dark green, and cascades of pink flowers in spring.

P. japonica 'Little Heath' AGM reaches just 60cm. Its dark leaves are edged silver (pink when young). White flowers appear in spring.

P. japonica 'Mountain Fire' AGM has emerging growth that appears orange-red, changing to bronze and then green. Densely packed clusters of white flowers appear in spring.

P. japonica 'Pink Delight' AGM is similar to the species but with delicate, rose-pink flowers.

P. japonica 'Prelude' AGM displays white flowers that emerge in early spring. It is another compact variety, reaching little over 60cm.

P. japonica 'Purity' AGM is selected for its abundant white flowers rather than new foliage growth. It grows to 1.2m.

P. japonica 'Sarabande' AGM carries cream-white flowers in spring. It is a compact form reaching 1m in height and spread.

P. japonica 'Valley Valentine' AGM features burgundy-red new growth fading to dark green, with red flowers following. It is a larger japonica form, reaching up to 4m in height.

P. japonica 'White Rum' AGM is a white-flowered form reaching 1m. Green foliage is edged with pink margins when young, maturing to cream.