Cheerful Giant AzaleaRhododendron (Knap Hill Hybrid) 'Cheerful Giant'
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Rhododendron (Knap Hill Hybrid) 'Cheerful Giant'
Outdoor Growing zone
Full Sun, Partial Sun
The Cheerful Giant Azalea is an upright deciduous shrub that grows over 6 feet tall, carrying huge trusses of a dozen flowers each on every branch. The large double flowers are ruffled and frilled, and a powerful golden yellow with apricot backs. This azalea is much more cold-resistant and easier to grow than evergreen azaleas, and it is a wonderful garden shrub for partial shade or full sun in beds or woodland areas.
Full sun is suitable for the Cheerful Giant Azalea in cool zones, and partial shade in warmer areas. It thrives beneath tall deciduous trees and prefers rich, well-drained acidic soil. It is not drought resistant and should be watered regularly in summer. No pruning or trimming is needed (or desirable) and it is normally free of pests or diseases.
So what is an azalea doing being hardy in zone 5? That’s because, in the wide world of azaleas and rhododendrons, there are also deciduous azaleas – that’s right, plants that lose their leaves in winter. This gives them a significant ‘edge’ in hardiness, so the deciduous Cheerful Giant Azalea is totally hardy in the coldest parts of zone 5, and we have reports of it growing successfully in zone 4. For that alone we would love this plant, but take one look at the spectacular flowers and you will see that it is doubly desirable. Growing in time well over 6 feet tall, with a sturdy upright habit, this plant is smothered in huge trusses of large, ruffled double flowers that are the most striking shade of golden yellow. Radically different from the low-growing evergreen azaleas that southern gardeners are familiar with, this is a magnificent shrub for woodland gardens and areas of partial shade. Although still preferring acid soil it is also more tolerant of neutral and even slightly alkaline soils too, so it’s a great choice for ‘less than perfect’ conditions. This show-stopping shrub is sure to wow everyone and become a special feature of spring in your garden.
The Cheerful Giant Azalea is a deciduous shrub growing to 5 feet tall within the first 10 years, ultimately doubling that height. When young it is about as wide as it is tall, but eventually it will become more column-like, staying no more than 6 feet wide. The stems are unusually sturdy and strong, with a bold upright form. The leaves are elliptical in shape, between 3 and 4 inches long, and dark green. In fall they take on unique metallic blue-green colors before dropping to show the winter profile of this shrub. Flowering takes place in mid-spring, in the middle of azalea season, and the flowers are clustered in large trusses of about 12 blooms, at the end of every branch. The flowers are double, packed with 15 petals, and they are incredibly frilly and ruffled, each one 3½ inches across, making an incredible display. The color is an extraordinary golden yellow, with apricot tones on the back of the blooms – ‘cheerful’ is exactly right to describe them, and yellow is a relatively rare color for azaleas. After this stunning display has ended no dead-heading is needed, since this variety doesn’t produce seeds – the flower stems will just wither away.
Deciduous azaleas are wonderful additions to shrub beds, especially in areas beneath and around trees. Grow this plant on the east side of your home, among evergreen azaleas and rhododendrons, or with other shrubs for partial shade. Give it a prominent place where its beauty can be seen from far and wide.
The Cheerful Giant Azalea is reliably hardy throughout zone 5 and will bloom well there. It is also likely to succeed in warmer parts of zone 4, in sheltered spots. It grows well in warmer zones up to zone 8.
This shrub will grow in full sun in cooler zones, and in partial shade in warmer areas. Morning sun and afternoon shade is ideal, and light partial shade, such as beneath tall deciduous trees, is also suitable. Although less ‘fussy’ than evergreen azaleas, the Cheerful Giant Azalea will grow best in acidic soils, with a pH of 6.0 or less. The soil should be rich and well-drained, so add plenty of lime-free organic materials like compost, peat-moss and rotted leaves, when preparing the planting area. Also use these materials as mulch.
Water regularly during dry spells – a steady supply of moisture on well-drained soil will give the best results. Mulch in fall to protect the roots from cold and to provide cover for water retention and coolness in the following summer. This plant is not drought resistant. It is generally free of pests or diseases and is best left to grow naturally, with little or no pruning. You can deadhead for appearance, but it isn’t necessary to prevent seeding, as this plant is sterile.
Anthony Waterer was one of the great early azalea breeders, and in the 1870s he created a group of deciduous azaleas that are named after his nursery, at Knap Hill in southern England. They have the American Rhododendron calendulaceum and the Chinese Rhododendron molle in their parentage, as well as the north American species R. arborescens and R. occidentale. It is these American species that give them their hardiness. In the 20th century the name continued to be used and expanded to include hybrids by Lionel de Rothschild at Exbury, England, and others created as far afield as Australia, Norway and Canada. The variety called Cheerful Giant is a Knap Hill type hybrid developed by S.E. Sorenson at Homestead Nurseries, Clayburn, British Columbia, Canada. It was a seedling from a cross between a deciduous azalea called ‘Whitethroat’ and a yellow seedling that Sorenson had previously developed. It was probably bred during the 1980s.
Deciduous azaleas are often overlooked, and some gardeners don’t even know they exist. Yet they bring us the most wonderful colors, especially in the yellow range, and they are much more hardy and not as difficult to grow as evergreen ones. Start your collection with the Gentle Giant Azalea, one of the most beautiful of them all, but order now, because our stock is limited and this variety is always sought after but in short supply.