Azalea mollis Peter Koster

The Azalea mollis 'Peter Koster' is a vigorous, old variety of Chinese Azalea, always considered one of the best in the 'red' category. In mid-spring, its funnel-shaped flowers gather in generous clusters, in light red tinged with pink. They open just before the dark green foliage, which takes on beautiful hues in autumn. Unlike Japanese Azaleas, this plant is deciduous and very hardy. Too little known and too little used, deciduous Azaleas are very graceful plants growing in chalk-free soil, with a whole host of qualities so do not hesitate to plant it in the garden or in a large pot on the terrace!

Rhododendron molle is a shrub from the heather or Ericaceae family, native to central and eastern China, which has given rise to most of the deciduous azalea varieties grown in gardens through hybridisation. 'Peter Koster', still widely planted in gardens, is a Dutch cultivar created by Koster M. & Sons in 1909. It is part of a series of hybrids derived from Rhododendron arboreum.

'Peter Koster' is a rather slow-growing shrub. It takes a while to develop, eventually forming a bushy, slightly spreading habit that is both slender and dense. By the age of 10, this Azalea will reach about 1.50 m (4 ft 11 in) in height with a spread of 1.30 m (4 ft 3 in). Its scentless flowers bloom over a long period in early to late May, depending on the climate; at the same time the very young leaves appear on the branches. The flowers, 4 to 5 cm (1.6 to 2 in) in diameter, are funnel-shaped and gathered in terminal clusters of up to 16. They are somewhere between pink and red, with a lighter centre and an upper petal that is discreetly speckled with brown. They are adorned with 5 long arched red stamens that contribute to the beauty of the blooms. The deciduous foliage consists of simple, oval-lanceolate leaves with smooth edges, arranged alternately on the branches. They vary from 5 to 10 cm (2 to 3.9 inches) in length, and are dark green on the upper surface, with a brown downy covering on the underside, and turn purple-red in October. Azaleas and Rhododendrons have a shallow root system that always needs to be kept moist, but they also dislike waterlogged soil which would suffocate the roots.

Deciduous Chinese Azaleas have fewer requirements than evergreen, Japanese Azaleas: they are very hardy and tolerate sunny positions, and even dry soil on occasion, depending on the hybrids. However, they give their best in cool climates, with distinct winters, planted in humus-rich, fertile, lime-free soil. They are beautiful shrubs for borders, with an attractive, informal habit, blooming twice a year and the perfect accompaniment to Japanese maples, which also change colour with the seasons, as well as Japanese camellias, or their graceful, often fragrant, autumn-flowering cousins, the Camellia sasanqua hybrids. 'Peter Koster', a timeless classic, will be magnificent when combined with other Chinese azaleas in shades of white, yellow, orange, peach, or red. The undeniable beauty of deciduous Azaleas merits the changes needed to create the conditions they prefer. They can also be grown in a large, carefully chosen pot, in suitable soil, and watered with lime-free water.