Azalea

Sun

Dappled shade or morning sun with afternoon shade; protect from hot afternoon sun and drying winds.

Water

Keep the shallow root zone evenly moist, especially during establishment, dry summers and container growth. Avoid standing water.

Soil

Acidic, humus-rich, well-drained soil, ideally pH 4.5-6.0. Use ericaceous potting mix in containers where garden soil is alkaline.

Height

2-4 ft (0.6-1.2 m)

Spread

2-4 ft (0.6-1.2 m)

Flowers

Late spring to early summer; typically red to orange-red in the species, with pink, white and patterned flowers among cultivated selections.

Foliage

Evergreen. Small, narrow, glossy dark-green leaves; some older leaves may drop or develop bronze tones in cold weather.

Growth

Slow to moderate.

Care needed

Medium

• Plant with the top of the root ball level with, or slightly above, the surrounding soil; do not bury the crown.
• Water deeply during dry spells, using rainwater where tap water is hard.
• Apply 2-3 in (5-8 cm) of pine bark or leaf mould, keeping mulch clear of the stems.
• Feed lightly with an ericaceous fertiliser in spring if growth is weak; avoid late-season feeding.
• Keep cultivation and digging away from the shallow roots.
• Use a container with drainage holes if your soil is alkaline or poorly drained.

Pruning. Prune immediately after flowering, shortening wayward shoots and removing dead or damaged wood. Avoid routine pruning later in the year because it removes developing flower buds.

Early spring

Check mulch depth and apply a light ericaceous feed if needed.

Spring

Plant when the soil is workable, watering thoroughly and leaving the crown unburied.

Late spring

Keep roots moist as flowers open, especially in pots.

Early summer

After flowering, lightly shape the shrub if necessary.

Summer

Water during dry spells and check leaf undersides for lace bugs.

Autumn

Renew organic mulch and water before winter if the soil is dry.

Winter

Shelter containers from drying winds and hard freezes; keep drainage holes clear.

• Plant in groups beneath open-canopied trees for a low flowering layer in acidic woodland borders.
• Combine with Japanese maples, ferns and mossy groundcover in Japanese-style gardens.
• Grow in ericaceous compost in courtyard containers where the garden soil is unsuitable.
• Use along shaded paths or at the front of shrub borders for a compact evergreen outline and seasonal colour.

Garden styles it suits: Japanese, Woodland, Modern courtyard, Traditional, Southern and Small-space.

Plant it with: Japanese maple, Japanese pieris, Camellia, Japanese painted fern, Hosta and Dwarf mondo grass.

Wildlife: Flowers are visited by bees and other insects. The evergreen branches provide modest shelter for small garden wildlife.

• Yellow leaves with green veins usually indicate iron deficiency caused by alkaline soil or water: check soil pH, use rainwater and move to ericaceous compost if necessary.
• Azalea lace bugs cause pale stippling above and dark specks beneath leaves: reduce drought stress, inspect undersides and use a locally approved insecticidal soap where labelled.
• Root rot causes wilting despite wet soil: improve drainage and avoid overwatering; remove badly affected plants rather than replanting into the same wet conditions.
• Brown leaf edges and scorched foliage can follow hot sun, drought or winter wind: provide afternoon shade, shelter and consistent moisture.

All parts, including leaves, flowers and nectar, contain grayanotoxins and are toxic to people, cats, dogs and horses. Eating them can cause vomiting, weakness, low blood pressure and dangerous heart disturbances; substantial ingestion can be fatal. Seek urgent medical or veterinary advice after suspected ingestion.

• Kurume azalea (Rhododendron Kurume Group)

  Usually flowers earlier in spring and often has smaller flowers in dense clusters. Cultivars overlap in appearance, so a reliable label may be needed.

• Japanese deciduous azalea (Rhododendron molle subsp. japonicum)

  Loses its leaves in winter and has larger leaves and conspicuous clusters of yellow, orange or red flowers.

• Common rhododendron (Rhododendron ponticum)

  Becomes a much larger shrub with broad, leathery leaves and rounded clusters of purple flowers, rather than the small leaves and few-flowered clusters of this azalea.

Azalea comes from the Greek azaleos, meaning dry, while indicum means 'of India', despite this species being native to Japan.

Propagation. Take semi-ripe cuttings in summer and root them in an acidic, free-draining medium under humid conditions. Low branches can also be layered. Seed-grown plants may differ from named selections.

Accepted botanical name

Rhododendron indicum

Native range

Japan.

Sources: GBIF (CC BY 4.0) and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.