Enkianthus are deciduous shrubs or small trees that boast lovely clusters of bell-shaped spring flowers as well as excellent autumn colour. They are not widely grown although they probably should be because they are so unfussy. However, they do need soil that is on the acid side.
They therefore often feature alongside rhododendrons, camellias, and Pieris in woodland settings.
According to the RHS the species count is 10, but others would disagree and argue that the total is as much as 17. They are in the acid-loving heather family, Ericaceae, and close relatives are Gaultheria and Vaccinium.
They all feature campanulate flowers that are borne in clusters or racemes. Enkianthus differ, however, in developing dry capsules after the flowers rather than fleshy fruits. Another distinctive feature of the plants is their leaves, which are arranged in rounded whorls. As a result, mature plants appear to have a tiered effect.
Enkianthus are found in a range of countries across north-east Asia, including China and Japan. A Japanese species, E. campanulatus Award of Garden Merit (AGM), is the best-known and most commonly available. It produces bell-shaped, prettily fringed flowers that are cream with pale-pink veins in May and June. The plant’s foliage then becomes rich red, orange and yellow in the autumn.
There are four recognised varieties of E. campanulatus AGM — var. campanulatus, var. palibinii, var. sikokianus and var. albiflorus. Several of these have red flowers, which has led to confusion in the trade with another Japanese species, E. cernuus f. rubens AGM.
It can be distinguished because it is a smaller plant, with smaller bells, of a dark-red colour.
Other good species include E. perulatus AGM, which is a shorter plant than the two above. It produces urn-shaped white flowers in sparse clusters and has foliage that turns to brilliant shades of red, orange and purple in the autumn months.
A choice but hard-to-find species is E. deflexus. This is an upright, large shrub or small tree featuring clusters of dainty creamy yellow flowers with attractive pink veins and a picotee edge.
Enkianthus require an acid or neutral soil. Ideally, this should be moisture-retentive and humus-rich. The plants prefer a position in partial shade but they will grow in full sun. It is best to give them a sheltered position because they do not fare well when subject to cold, drying winds, although they are all reliably hardy, tolerating between -10°C and -20°C.
What the specialists say
Charles Williams, owner, Burncoose Nurseries, Cornwall
"I really like Enkianthus and that is why we have been assembling a collection at Caerhays to foster my preference. They have exceptionally beautiful flowers, are easy to grow and easy to propagate. But they are, and remain, little-known and are not grown widely enough.
"E. campanulatus is the most widely cultivated species, endemic to much of Japan, and there are four recognised varieties in the species. There are also many excellent named forms such as ‘Hollandia’, ‘Red Velvet’, ‘Red Bells’, which is often confused with E. cernuus, and ‘Wallaby’, the only true dwarf Enkianthus.
"E. deflexus is my clear favourite as regards colour. The bells are yellowish red with darker lines and the picotee edge is a deep red verging on purple. Ernest Wilson described E. deflexus as one of the most beautiful shrubs in the western Chinese mountains and I would entirely agree with this.
"Once you have got over the excitement of the wonderful colours and shapes of Enkianthus flowers there are further treats in store. All Enkianthus are deciduous and produce startling autumn colour to rival acers, Nyssas, liquidambars or cherries.
"E. campanulatus produces a stunning and vibrant autumn display ranging from yellow to orange and crimson, while E. perulatus produces splendid brilliant red autumn colour, sometimes yellowish/orange in milder situations."
Matthew Pottage, deputy curator, RHS Garden Wisley, Surrey
"Enkianthus are true stars of the wild garden at Wisley where the sheltered, humid environment in dappled damp shade suits them down to the ground. However, it is this range of rather specific conditions that brings us such good results and there is nothing more pleasing than seeing the masses of bell-like flowers in early May, lining the branches.
"Some of the Wisley specimens are very old and would resemble a small tree to those with a small garden, and coupled with the flame-red autumn colour are simply magnificent plants to have in the collection.
"Wisley is not a warm garden and their long-term success proves their reliable, cold-hardy nature. Older plants have succumbed to honey fungus, but they are generally trouble-free for us.
"Their growing requirements are not to be ignored, however. Plants are not especially cheap and are not something for experimenting with. They dislike cold, drying winds, generally windy sites, soil of a high pH and dry conditions. Plants can be slow to establish and need moisture-retentive, humus-rich soil for the very best results.
"At Wisley, E. campanulatus is a real stunner and the white-flowered form var. albiflorus also performs well. A young plant of E. campanulatus ‘Pagoda’ shows real promise with its very obviously whorled branch formation. For a little more red in the flower colour, the cultivar ‘Red Bells’ does well for us, as does the white-flowered E. perulatus, which again has super autumn colour.
"The best Enkianthus can be seen at RHS Wisley and RHS Rosemoor. In contrast, the heavier soils and more exposed nature of RHS Hyde Hall and RHS Harlow Carr mean they do not have significant representations in their collections, owing to the growing requirements."
Species and varieties
E. campanulatus AGM (H5) is a large, deciduous shrub of erect habit. It produces clusters of small, bell-shaped, cream-to-pink flowers with darker-pink margins from late spring to midsummer. Renowned for its autumn colour, when its foliage turns brilliant shades of red, orange and yellow. Height and spread: 4-5m.
E. campanulatus ‘Red Bells’ has bell-shaped cream flowers with faint red veins and red-tipped petals. The foliage turns a lovely red in autumn. Height and spread: 4-5m.
E. campanulatus var. albiflorus is a lovely white-flowered form.
E. campanulatus var. campanulatus has pale-yellow to reddish flowers.
E. campanulatus var. palibinii has beautiful russet pink flowers with delicate veining.
E. campanulatus var. sikokianus produces long racemes of reddish flowers. Height: 4-5m.
E. campanulatus ‘Wallaby’ is a dwarf variety with pink flowers. Hardy down to -20°C. Height and spread: 75cm.
E. cernuus f. rubens AGM (H5), or the drooping red Enkianthus, is a medium-sized deciduous shrub. It has deepest-red flowers with fringed lobes from late spring. Foliage turns reddish/purple in the autumn. Height: 2.5m.
E. chinensis produces creamy flowers that are actually striped with yellow, orange and red. Its distinctive feature is picotee edging, which is pinkish/red. One of the last species to flower, in late May and on into June. Height: 3.5m. Spread: 2m.
E. deflexus is a medium-sized shrub that bears clusters of dainty creamy yellow flowers with attractive pink veins and a picotee edge of deep reddish/purple. Its pubescent leaves differentiate it from E. chinensis. Height: 3m.
E. perulatus AGM (H5) is a compact, medium-sized deciduous shrub that produces small, pure white, urn-shaped flowers in clusters in spring. Its ovate leaves turn red and orange in autumn. Height and spread: 2m.
Thank you to Floramedia, which supplied images for this article from its photo library