These are actually in the genus Rhododendron (refer to Rhododendron) though they are generally treated separately. They are smaller growing shrubs than other rhododendrons, with both smaller leaves, and generally a lesser height. (see classification below).
The Indicas and Kurumes are adaptable shrubs and have a wide variety of uses, including (depending on variety). Mollis azaleas are less hardy and do not do well in milder climates.
All are useful for providing spot colour in a shrubbery, or as a massed display for an overwhelmingly spectacular effect.
They are also used as hedges; tub plants (need to watered very regularly), in hanging baskets (temporary - remove after three or so years and plant into the garden - keep well watered) or as a bonsai specimen.
Low growing varieties may be used as borders.
Azaleas are also trained as Standards (usually tall Indica varieties).
Azaleas are generally low growing forms of rhododendron which fall into one of three different groups (see below under Cultivars); few grow more than 1m tall, leaves are mainly around 2-3cm long or shorter.
Flowers are to be found in a wide and brilliant range of colours.
A protected position in full sun to part shade is best. Avoid areas with hot, dry winds. All grow well in temperate climates, indicas grow better into the sub-tropics than the others.
They prefer acidic, fertile and moist soil. Feed with well rotted manure or compost at least twice annually.
Lightly prune annually to maintain shape and improve vigor.
Propagate by semi-hardwood cuttings.
There are a range of pests that attach Azaleas. Some authorities recommend companion planting lilies, garlic or chives to deter pests. Pests may include lacewings, leaf miners or mites. Mites are the most likely but can usually be controlled by releasing predatory mites.
Diseases may include leaf spots, petal blight and root rots. These are less likely if drainage is good and humidity is minimised. In warmer, wet climates, space plants to improve ventilation.
Most modern azaleas have resulted from a lot of plant breeding (hybridizing), carried out over the past 200 years or so.
The Azaleas most commonly cultivated in Australia fall into three main groups:
1/ Indica Hybrids
These are evergreen, sometimes tender, small shrubs derived mostly from R. indicum,
R. mucronatum, and R. Simsii. Flower colours include white, pinks, reds, mauves, and purples.
Single flowered Indicas are usually quite hardy, and have a tall upright habit (growing to 3m tall), with foliage remaining fairly dense. Flowering generally begins around Mid-September and lasts for about three weeks. Double and Semi-double Indicas are available in a wide range of flower sizes, shapes and colours (e.g. pinks, reds, mauves, purples), including stripes and flecks. Indicas vary considerably in their degree of hardiness, height and competitiveness. There is also wide variation
in the length of the flowering season, with some carrying odd blooms for all but the hottest months with peak flushes in spring or sometimes autumn, while others have only a spring flush. Example A. indica ‘Gretel’.
2/ Kurume Hybrids
Derived mainly from R. Kaempferi and R. kiusianum. They are small, evergreen shrubs. Some may be tender in colder areas. Flower colours include white, pink, scarlet to purple, sometimes striped or flecked. Kurumes are sometimes offered as miniatures or dwarfs. Some varieties can reach up to 3m tall. They tend to be twiggier, and have denser foliage than the Indicas. Like the Indicas there is great variation in height and spread. Flowers and leaves are small, so spot flowers often go unnoticed, but usually they have a mass of flowers in spring creating a spectacular show. They are good for hedging and topiary. The Indicas are less suited to hedging because of their more open growth habit. Example A. kurume ‘Best Pink’.
3/ Mollis Hybrids
Deciduous small shrubs derived from R. molle and R. japonicum. They have trumpet-shaped flowers to 6-7cm across in early spring, with colours including white, yellow, and orange.
Growth is generally upright. Foliage is more open than for Indicas and Kurumes, and leaves are larger. They generally prefer more sheltered conditions than Indicas or Kurumes. Example R. azalea mollis ‘Brilliance’.
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