Torch azalea

Torch azalea: how do you recognise it?

Habit

Dense, branching shrub about 2 m tall and wide, semi-evergreen.

Foliage

Elliptic to lance-shaped, 3–7 cm, with brown hairs. There are two kinds of leaves: thin spring leaves that fall in autumn and smaller summer leaves that survive the winter.

Flower

Funnel-shaped, 4–5 cm, orange-red to salmon-red, in groups of 2–3 in May. Pink and red forms also exist.

Fruit

A small, hairy capsule that splits open in autumn.

Roots

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

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

Why grow it?

• Bright orange-red flowers in May, in half shade where few other shrubs flower so freely.
• Hardy to about −25 °C and one of the hardiest Japanese azaleas.
• Semi-evergreen: part of the foliage stays on the shrub in winter.
• The flowers are visited by bees and bumblebees.
• A compact, easy shrub that needs little pruning.

Torch azalea: where does it grow best?

• Half shade is ideal: in full sun the flowers fade quickly and the leaves can scorch.
• 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 and from morning sun after a night frost. Allow 1.5–2 m of space.

Light

Partial shade

Soil type

Sand, loam or peat

Acidity

Acid

Moisture

Normal

Size

2 m tall, 2 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Japanese maple: Fine leaves and good autumn colour above the azalea; a classic combination.
• Pieris: An evergreen ericaceous shrub that flowers in spring.
• Hosta: Large leaves in the same half shade.
• Coral bells: Coloured foliage at the base that makes the orange flowers stand out.
• Ferns: Fresh foliage in half shade and humus-rich soil.

Torch 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, pine-needle mulch or oak leaves 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 flowers 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 in half shade and keep the soil cool and acid with needle mulch or leaf mould: in full sun the flowers fade, on chalky soil the leaves turn yellow.

Torch azalea: when to prune it?

Pruning months: June.

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

How:

• Snap or cut off spent flowers if you wish.
• Shorten overlong branches just above a side shoot to adjust the shape.
• Remove dead, weak and crossing branches at the base.
• 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

Softwood and semi-ripe cuttings

In June–August: take 6–10 cm cuttings of this year’s shoots, remove the lower leaves and insert in a mix of acid seed compost and sand under plastic. They root slowly.

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.

Torch azalea: how does it get through the winter?

Hardy to −25 °C.

• Hardy to about −25 °C: usually fine in Flanders, but choose a sheltered spot.
• A layer of leaves or needle mulch around the base protects the shallow roots, especially on young plants.
• In severe frost and bright winter sun the persistent leaves can scorch; half shade and a windbreak prevent this.
• 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

• Azalea gall: Swollen, pale green, fleshy galls on leaves or shoots in spring. Remove them and bin them before they turn white and spread spores.
• Rhododendron lace bug: Pale speckles on the upper leaf surface and shiny black droplets underneath, mainly in sun. Move it to more shade, rinse the plants with water and remove badly affected leaves.
• 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.
• 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.

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. Water with rainwater in dry weather.
• June: After flowering, remove spent flowers and prune lightly.
• July: Water in dry weather. Watch for lace bug and notched leaf edges.
• August: Water in dry weather. Apply nematodes against vine weevil grubs.
• September: Plant. Top up the mulch.
• October: Plant. Top up the mulch. Part of the foliage falls.
• November: Rest. Fallen leaves can stay as mulch.
• December: Rest. In bright sun and frost, keep an eye on the persistent leaves.

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 is named after Engelbert Kaempfer, a German physician and naturalist who stayed in Japan from 1690 to 1692 and described plants there.
• The shrub has two kinds of leaves: large spring leaves that fall in autumn and smaller summer leaves that survive the winter. That is why it is called semi-evergreen.
• In the wild it grows on mountain slopes in Japan. Crossing it with other azaleas produced many hardy garden azaleas.