Western azalea

Western azalea: how do you recognise it?

Habit

Open, deciduous shrub about 2 m tall and wide, developing a broader crown over the years.

Foliage

Elliptic to obovate, 4–8 cm long, bright green; turns yellow, orange or red in autumn.

Flower

Funnel-shaped, up to about 6 cm, white to pale pink with a yellow to orange blotch, in clusters in May–June.

Scent

The flowers smell sweet, especially on a warm, still day.

Roots

Shallow and finely branched: they dry out quickly and must not be disturbed by digging or hoeing.

Flowering: May–June · Plants: March–April and September–October · Pruning: June–July

Why grow it?

• Large, sweetly scented flowers in May–June, ideal next to a terrace or along a path.
• White to pink flowers with a yellow blotch: a soft, light colour scheme in half shade.
• The leaves often turn yellow to orange-red in autumn.
• The flowers are visited by bees and bumblebees.
• Little work: hardly any pruning.

Western azalea: where does it grow best?

• Half shade or light shade; also a sunnier spot if the soil stays moist. Avoid hot afternoon sun.
• Acid soil (pH about 4.5–5.5): sand or loam rich in humus. Never use lime or chalky compost.
• Evenly moist but well drained; it dislikes both wet feet and drying out.
• Sheltered from cold east wind. Plant it near the terrace or along a path so you notice the scent. Allow 1.5–2 m of space.

Light

Sun and partial shade

Soil type

Sand, loam or peat

Acidity

Acid

Moisture

Normal

Size

2 m tall, 2 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Ferns: Fresh green foliage in the same moist, acid soil.
• Japanese maple: Fine leaves and good autumn colour above the azalea.
• Hosta: Large leaves in the same half shade.
• Wood anemone: A native spring flower for underplanting in light shade.

Western azalea: when and how to plant it?

Plant in March–April and September–October.

1. Plant in March–April or September–October, when the soil is neither frozen nor waterlogged.
2. Dig a hole 2–3 times as wide as the root ball, but no deeper. Mix the excavated soil with leaf mould or peat-free ericaceous compost.
3. Soak the root ball in a bucket of water until no more air bubbles rise, then gently tease out the roots.
4. Set the root ball so its top is level with, or slightly above, the soil: never plant deeper than in the pot.
5. Firm the soil and water straight away, preferably with rainwater.
6. Spread a 5–8 cm layer of leaf mould or pine-needle mulch around the base.

Care

Water

In dry weather give a good watering every week, preferably rainwater: tap water often contains lime and makes the soil less acid.

Feeding

In April–May, an ericaceous fertiliser or organic fertiliser. Not after July.

Mulching

Renew the leaf mould or needle mulch every spring. Do not dig or hoe around the shrub: the roots lie just below the surface.

Spent flowers

You may snap off spent trusses by hand without damaging the young buds below. It is not essential.

Avoid lime

Do not use lime, dolomite or chalky compost nearby; the leaves would turn yellow.

Tip: Plant it near the terrace or along a path, sheltered from cold wind: you enjoy the scent in May–June and run less risk of frost damage to the buds.

Western azalea: when to prune it?

Pruning months: June–July.

When: It needs little pruning. Do it just after flowering, in June–July, because next year’s flower buds form in summer.

How:

• Snap or cut off spent trusses if you wish.
• Remove dead, weak and crossing branches at the base.
• Shorten overlong branches just above a side shoot to adjust the shape.
• An old, bare shrub can be cut back to 30–50 cm above the ground in March: it usually regrows, but will not flower that year.

Caution: Do not prune in late summer or autumn: you would cut off next year’s flower buds.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Layering

In spring, bend a low, flexible branch down, peg it into acid, loose soil and put a stone on top. Separate it with its roots after one or two years.

Seed

Scatter the fine seed in January–March on moist acid seed compost without covering it, in the light at 15–20 °C. Seedlings grow slowly and do not always resemble the parent.

Western azalea: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: usually fine in Flanders in a sheltered spot.
• Protect young plants in the first winters with a thick layer of leaves or needle mulch around the base; in severe frost, cover them with fleece.
• In a pot the roots freeze more easily: stand the pot against a wall, wrap it in hessian and water on frost-free days.

Diseases and pests

• Chlorosis: Yellow leaves with green veins on soil that is too chalky. Acidify the soil with needle mulch and leaf mould, water with rainwater and give an ericaceous fertiliser.
• Powdery mildew: A white, powdery coating on the leaves, mainly in late summer in dry weather. Water at the base, leave space between plants and remove affected leaves.
• Vine weevil: Half-moon notches in the leaf edges in summer; the grubs eat the roots. Apply nematodes in August–September to warm, moist soil.
• Frost damage: Brown, shrivelled buds or shoot tips after severe frost or a late night frost. Plant in a sheltered spot, cover young shrubs with fleece and only prune once it is clear what is dead.

Through the year

• March: Plant. Ericaceous fertiliser. Renovate old shrubs if needed (no flowers that year).
• April: Plant. Top up the leaf mould or needle mulch.
• May: Flowering and scent begin. Water with rainwater in dry weather.
• June: Flowering. After flowering, remove spent trusses and prune lightly.
• July: Water in dry weather. Watch for notched leaf edges.
• August: Water in dry weather. Apply nematodes against vine weevil grubs.
• September: Plant. Collect seed when the capsules open.
• October: Plant. Autumn colour. Top up the mulch and prepare young plants for winter.
• November: Rest. Fallen leaves can stay as mulch.

Edible and useful

Not edible. Rhododendrons and azaleas are poisonous in all their parts, including the flowers and nectar: they contain grayanotoxins, which cause drooling, vomiting, weakness, a slow heartbeat and low blood pressure. Goats, sheep and alpacas above all, but also horses, cattle, rabbits and guinea pigs become seriously ill from them, sometimes after only a small quantity of leaves; dogs and cats are at risk too. So never throw clippings over the fence of a field or into a pen or hutch, do not give them to animals, and do not pick greens for rabbits among the shrubs; if in doubt, call your vet at once. In children who put a leaf or flower in their mouth or suck nectar from the flowers, as they do with dead-nettle, it usually goes no further than a burning mouth and nausea, but teach them not to do it. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The species name occidentale means ‘of the west’. Most wild azaleas come from the eastern United States or Asia; this one grows on the west coast.
• It is one of the wild parents of the fragrant azalea hybrids, including the Knap Hill–Exbury azaleas.
• In the wild it often grows along streams and in moist coastal areas in California and Oregon.