Why GRUMPY will make you HAPPY...
Rhododendrons can top 80ft, so if you need a small variety to add glamour to your plot, send for the Seven Dwarfs!
THE last time I was in Cornwall, I spent a few hours exploring the magnificent Trewithen Garden, near Truro. It was a sunny day in early May and the estate’s famed and venerable rhododendrons were in full flight, staging an unforgettable display in shades of white, yellow, pink, red and purple.
Many of the specimens on view were enormous and certainly not the kind of thing anyone with a modest plot could accommodate – reinforcing the impression that rhododendrons are only suitable for those with lots of space.
Yet this tribe of trees and shrubs is more diverse than you might imagine. Sure, there are some whopping great things but there are also compact ones ideal for smaller gardens.
A number will even thrive in pots of ericaceous compost, allowing those with alkaline soil to raise these spring stunners.
Rhododendrons have a wide distributional range, with wild plants hailing from Europe, Asia, Australasia and North America.
They flourish in a diverse range of habitats, from dense tropical jungles to snow-covered mountains, although the bulk are native to the Himalayas, which is home to an estimated 600 species.
AFLURRY of wild species arrived in Britain during the 19th and early 20th Century, collected by plant hunters like George Forrest and Ernest Wilson. Many expeditions were funded by the landed gentry, who were given a share of the discoveries. This trade-off explains why old rhododendrons are often found in the gardens of stately piles.
There are about 1,000 different species in the wild, but plant breeding has provided gardeners with a choice of nearly 2,000.
Ranging from ground-covering shrubs to 80ft giants, these evergreen and deciduous treasures have tubular, funnel, saucer or trumpet-shaped blooms, depending on variety.
One of my favourites is Cornish Red, with its trusses of red-purple flowers. Alas, this beast can grow to 40ft, so is only suitable for those with extensive grounds.
In medium to large gardens, consider Purple Splendour or Loderi King George, whose 6in wide, white blooms are scented. Both grow a smidgen over 10ft.
Among the best for smaller gardens are the many varieties of Rhododendron yakushimanum (sometimes described as yak hybrids) that typically hit 2½-3ft in height after about a decade. The group includes the so-called Seven Dwarfs series. Launched in the 1970s, it includes the varieties Dopey and Grumpy.
If you don’t have right soil for rhododendrons, raise compact ones in large containers. Another option is to seek out plants labelled ‘Inkarho’. These have been developed by attaching the variety to the roots of a species found in a German limestone quarry. As result, plants are a bit more lime-tolerant than others.
Apart from these types, most rhododendrons will thrive in moist, but well-drained acidic soil with a pH between 4.5-5.5 – it’s easy to check acidity with a simple testing kit. They’ll perform best in a position that’s sheltered from cold winds, either in full sun or partial shade – avoid deep shade as plants will flower poorly.
Use taller varieties as standalone specimens or set within a woodland-style setting.
Medium-sized ones are ideal for adding structure to beds and borders, while smaller varieties make good ground-cover plants. A new introduction called Bloombux makes a good alternative to box hedging thanks to its tiny leaves.
To keep plants looking tidy and ensure a great display of flowers next spring, deadhead flowers regularly to encourage plants to produce more flower-bearing shoots, rather than putting energy into seed production. Use your thumb and forefinger to snap the heads off, just above a set of leaves.
Rhododendrons are generally trouble-free but may suffer from bud blast, a fungal disease that causes buds to turn brown and die – pick off infected ones and destroy.
The disease is spread by leafhoppers, pesky sap-sucking insects that are most active in late summer but which can be controlled with organic pesticide.