Cheerful Giant Azalea

Rhododendron (Knap Hill Hybrid) 'Cheerful Giant'

Cheerful Giant Azalea

Rhododendron (Knap Hill Hybrid) 'Cheerful Giant'

This product is currently out of stock and unavailable.


How are the heights measured?

All tree, and nothin' but the tree! We measure from the top of the soil to the top of the tree; the height of the container or the root system is never included in our measurements.

What is a gallon container?

Nursery containers come in a variety of different sizes, and old-school nursery slang has stuck. While the industry-standard terminology is to call the sizes "Gallon Containers", that doesn't exactly translate to the traditional liquid "gallon" size we think of. You'll find we carry young 1-gallons, up to more mature 7-gallons ranging anywhere from 6 inches to 6ft.

How does the delivery process work?

All of our orders ship via FedEx Ground! Once your order is placed online, our magic elves get right to work picking, staging, boxing and shipping your trees. Orders typically ship out within 2 business days. You will receive email notifications along the way on the progress of your order, as well as tracking information to track your plants all the way to their new home!

Why are some states excluded from shipping?

The short & sweet answer is: "United States Department of Agriculture Restrictions." Every state has their own unique USDA restrictions on which plants they allow to come into their state. While we wish we could serve everyone, it's for the safety of native species and helps prevent the spread of invasive disease & pests. We've gotta protect good ole' Mother Nature, after all.

About Me


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.

  • Huge trusses of drop-dead gorgeous ruffled golden flowers
  • Deciduous species easier to grow than evergreen azaleas
  • Becomes a tall bush over 6 feet high
  • Less demanding for acid soil
  • More winter-hardy than evergreen azaleas

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.

Plant Hardiness Zones 5-8
Mature Width 4-6
Mature Height 4-10
Sun Needs Full Sun, Partial Sun
Zones 5-8

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.

Growing the Cheerful Giant Azalea

Size and Appearance

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.

Using the Cheerful Giant Azalea in Your Garden

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.

Sun Exposure and Soil Conditions

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.

Maintenance and Pruning

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.

History and Origin of the Cheerful Giant Azalea

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.

Buying the Cheerful Giant Azalea at the Tree Center

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.

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Cheerful Giant Azalea

Rhododendron (Knap Hill Hybrid) 'Cheerful Giant'