Rhododendrons are the shrubs most likely to make gardeners happy in the Pacific Northwest.
Thatâ€™s because rhodos love our acidic soil, mild temperatures, large number of canopy trees, and (usually) high rainfall.
Even better, the shallow roots of rhodos make them easy to transplant.
Also, weeds are reluctant to grow underneath them, because the heavy, evergreen leaves block light.
Then there are the spectacular flower clusters in spring.
As well, itâ€™s easy to find a rhododendron to suit your garden, because there are more than 1,000 species and innumerable cultivars.
Theyâ€™re popular with plant breeders because they hybridize very easily.
Breeders also like rhodendrons that are easy to work with.
These selections will root easily, resist rhododendron diseases and flower early.
Especially for people in smaller spaces, itâ€™s important to choose varieties that they love the look of now, and that wonâ€™t annoy them later with excessive growth.
Some rhododendrons can stretch far and wide as they get older. That means pruning may be necessary if theyâ€™re planted near a door or under a window.
Hybrid rhodos with rough bark usually respond well to pruning.
Rhodos with smooth bark may have trouble.
And both kinds are unlikely to flower on the new shoots for a few years.
The dryness under roof overhangs and alkalinity from concrete foundations can also cause problems for rhododendrons.
People with very small space would do best with extremely compact rhododendrons, including some nice purple-blues such as â€˜Blue Birdâ€™ or â€˜Blue Diamondâ€™ â€“ or the paler â€˜Ramapo.â€™
The small-leaf rhodos handle sun and moderate drying better than larger-leaf kinds.
Large-leaf rhodos do best in fairly moist, dappled shade.
Small-leaf rhodos tend to grow to about a metre (three feet) high over 10 years, according to nursery labels.
Those labels never mention eventual heights subsequently attained, but very old compact rhodos can reach two metres (six feet) and more.
Many rhododendrons never stop growing.
Somewhat less compact, but still small and shapely is the very popular â€˜PJMâ€™ rhodo, which has very bright pink flowers.
â€˜PJMâ€™, is densely branched, has leaves that are aromatic (when crushed), and turn a reddish-brown through winter. It usually reaches up to 2.4 metres and spreads up to about 1.3 metres (four feet).
Another hugely loved and easily available rhodo family is the Yakushimanums (a.k.a. Yaks). They have compactly branched, rounded bushes that produce pink buds which open to pink or white flowers. The plants are very hardy, and are tolerant of harsh conditions.
Rhodo ponticum isnâ€™t as popular as it was before people discovered it can thrust up shoots from its roots. In Scotland and Ireland, it has invaded many acres.
But the purple-flowered R. ponticum with white-edged leaves is still sold.
Another variegated-leaf rhodo is â€˜President Roosevelt.â€™ It has red flowers and yellow-edged leaves.
Some unusual rhodos include the very early pale pink â€˜Christmas Cheerâ€™ and the equally early R. mucronulatum which opens pink flowers on deciduous branches.
â€˜Hoteiâ€™ has beautiful butter-yellow flowers, while R. augustifolium offers varying shades of blue.
Rhodos need to be planted in airy and acidic soil to which bark and/or peat and compost have been added.
Bark mulch is especially useful, because it holds in moisture, adds acidity, and helps to aerate the soil. Itâ€™s also very useful as a top dressing.