Japanese Azalea is the common name for evergreen to semievergreen rhododendrons, known generically as Rhododendron japonicum. Most are complex hybrids or species from Japan such as Kyushu azalea (R. kiusianum), Torch azalea (R. kaempferi), Kurume azalea (R. obtusum x kiusianum), and Kirishima azalea (R. obtusum), among others. These have been bred for over 500 years and with thousands of cultivars available, it can be a difficult decision to choose just one for your garden. So, here a is a quick overview of some of the varieties that can be found locally, followed by some cultural advice.

‘Ben Morrison’ (Zone 7 / 4’ tall)

Spectacular bicolour blooms of salmon-pink generously edged in white make this hard-to-find cultivar worth looking for.

‘Blaauw’s Pink’ (Zone 6 / 3-4’ tall)

Lightly fragrant coral-pink flowers with a hose-in-hose form are very popular with local gardeners.

‘Blue Danube’ (Zone 5 / 4’ tall)

An older cultivar with unusual magenta-violet trumpet flowers accented with darker purple spotting. Good plant vigour.

‘Elsie Lee’ (Zone 5 / 3-4’ tall)

This ‘Desiree’ x ‘Rosebud’ hybrid features showy lavender-pink semidouble blooms, usually in May.

‘Gaiety’ (Zone 6 / 3’ tall)

Over the years, I have seen this variegated cultivar go by many names, including ‘Variegata’ and ‘Silver Sword’. The bright pink flowers age with reddish overtones and this variety is only semievergreen.

‘Girard’s Fuchsia’ (Zone 6 / 3-4’ tall)

One of my personal favourites, the intense fuchsia-coloured flowers literally glow at a distance.

‘Girard’s Hot Shot’ (Zone 5 / 3-4’ tall)

This cultivar has unusual reddish-orange ruffled blooms that mimic the intense colours we have come to expect from deciduous azaleas.

‘Gumpo Pink’ (Zone 7 / 2-3’ tall)

A compact variety with very dense foliage that hugs the ground, overlaid with large shell-pink flowers.

‘Hahn’s Red’ (Zone 6 / 3-4’ tall)

An older cultivar featuring large cherry-red blooms and bronze winter foliage.

‘Hino Crimson’ (Zone 6 / 3’ tall)

Our top-selling Japanese azalea! This one also adorns my front yard. It features tiny crimson blooms that literally smother the canopy.

‘Hino White’ (Zone 6 / 3’ tall)

Snow-white blossoms can be found on this variety from April to May. A dwarf cultivar, ‘Hino White Dwarf’ (2’ tall) is also available, with the latter entirely covering the foliage in pure white blooms.

‘Johanna’ (Zone 6 / 4’ tall)

The glossy green foliage turns an intense reddish-purple in winter and is covered with large ruffled red flowers in spring.

‘Perfecto Mundo Double Purple’ (Zone 6 / 3’ tall)

A reblooming azalea from Proven Winners with double lavender-purple blossoms until late summer.

‘Pink Macrantha’ (Zone 5 / 3-4’ tall)

Large hose-in-hose pink flowers are produced from mid-spring through to early summer.

‘Red Red’ (Zone 5 / 3’ tall)

Exceptionally large funnel-shaped bright red blooms typically envelop the entire foliage canopy.

‘Rosebud’ (Zone 6 / 3’ tall)

An Award of Garden Merit (AGM) winner with unusual rosy-pink double blooms in abundance.

‘Vuyk’s Scarlet’ (Zone 5 / 3’ tall)

Another AGM winner with masses of crimson-red blossoms that generally appear in early May.

Sun Exposure

Here in coastal BC, Japanese azaleas thrive in partial sun but can tolerate full sun exposures when planted in evenly moist soils and sheltered from drying winds. While they will grow in open shade, your flowering will be limited.

Soil Type

Japanese azaleas prefer well-drained, organic soils with an acidic pH of around 4.5-6. If you have sandy soils, consider adding Sea Soil compost to increase the water and nutrient holding capacity.

Watering

Being rhododendrons, Japanese azaleas have shallow, fibrous root systems that are prone to drying out, so be diligent with the watering when establishing new specimens. They prefer a natural mulch (to conserve moisture in summer and protect from ground frosts in winter) such as hemlock or fir, as opposed to aggregates like lava or river rock, as the latter reflect too much heat.

Pruning

Prune your Japanese azaleas as soon as the flowers fade or brown, using hand pruners or shears (for finer stems) to cut to just above last year’s canopy. Pruning later in the season will result in the loss of flower buds.

Fertilizing

Limit your bonemeal when planting (it raises the pH) and always use a dedicated rhododendron and azalea fertilizer, as it contains soil acidifiers and necessary trace elements. Fertilize in early spring, a second fertilization in June is often necessary here due to our excessive rains (which leaches the nutrients) or on sites with sandy soils.

Diseases

Most issues with Japanese azaleas are cultural in nature, including yellowed leaves (pH too high), scorched leaves (wind or sun exposure), and dead branches (winter damage). One fungal disease worth mentioning is Azalea leaf gall, symptoms of which are distorted fleshy leaves that turn whitish or pink-tinged and look quite ominous. The solution is to simply remove infected foliage and spray affected plants with fixed copper just before bud break in spring and three weeks later, as this provides a protective coating.