Alpenrose

Alpenrose: how do you recognise it?

Habit

Low, dense, evergreen shrub about 0.8 m tall and 1 m wide; slow growing.

Foliage

Leathery leaves 2–4 cm long; glossy dark green above, rusty brown below because of small scales. The leaf edge is hairless.

Flower

Small funnel-shaped flowers in clusters at the shoot tips, dark pink to carmine, in June–July.

Fruit

Small capsules that split open in autumn; the seed is as fine as dust.

Roots

Shallow and fibrous. They dry out quickly and like cool, moist soil.

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

Why grow it?

• A compact, evergreen shrub that stays attractive in winter too.
• Flowers in June–July, when most other rhododendrons have finished.
• Fully hardy, to about −30 °C.
• Suits a rock garden, heather garden or cool border and gives it a mountain feel.
• The flowers are visited by bees and bumblebees.

Alpenrose: where does it grow best?

• Half shade is the safest in Flanders; sun is fine if the soil stays cool and moist. Avoid hot afternoon sun.
• Acid, humus-rich, loose soil (pH about 4.5–5.5): sand, loam or peaty soil, well drained. No lime.
• Evenly moist, with no standing water. It does not tolerate prolonged drought or heat.
• A north-facing spot or a place between stones in a rock garden is ideal. Allow 80–100 cm per plant.

Light

Sun and partial shade

Soil type

Sand, loam or peat

Acidity

Acid

Moisture

Normal or wet

Size

0.8 m tall, 1 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Ling heather: Acid-loving heather for the same position, with a long flowering season.
• Cowberry: A low, evergreen acid-loving plant that covers the ground.
• Mountain pine: A small conifer for a mountain feel.
• Ferns: Fresh foliage in half shade and humus-rich soil.

Alpenrose: when and how to plant it?

Plant in March–April and September–October.

1. Plant in March–April or September–October.
2. Dig a wide but shallow hole and mix the soil with leaf mould or peat-free ericaceous compost. Add a few handfuls of coarse sand for drainage.
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 plant at the same depth as in its pot, preferably slightly higher, and firm the soil. Water straight away with rainwater.
5. Spread a 5 cm layer of needle mulch or pine bark around the base. Flat stones between the plants keep the roots cool.

Care

Water

Never let it dry out completely, especially in the first two years and in a pot. In dry, hot weather water with rainwater; tap water often contains lime.

Feeding

Little: a light dose of ericaceous fertiliser in April. In nature it grows on poor soil.

Mulching

Renew the needle mulch or pine bark every year; leaf mould also works.

Spent flowers

Not essential. You can snap off the spent clusters by hand to limit seed formation.

Soil

Do not dig or hoe around the plant: the roots lie just below the surface.

Tip: Water it with rainwater and lay flat stones around the base: they keep the roots cool, as in the mountains.

Alpenrose: when to prune it?

When: It is hardly pruned. Cut off dead twigs in March and remove spent clusters in July–August.

How:

• Snap or cut off spent clusters without damaging the young shoots below.
• In spring, cut dead or frosted twigs back to healthy wood.
• Do not clip it into shape: keep the natural, rounded habit.

Caution: It grows slowly, so prune as little as possible.

Pruning calendar and basic rules

Propagation

Layering

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

Seed

Scatter the dust-fine seed in January–March on moist acid seed compost without covering it, and keep it light and cool. Seedlings grow slowly and flower only after many years.

Alpenrose: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C. In the mountains a thick blanket of snow protects it from hard frost.
• Evergreen leaves can scorch in bright winter sun and dry wind when the ground is frozen: put it in half shade or shelter it, and water on frost-free days.
• In a pot: stand the pot against a wall and wrap it in hessian so the roots do not freeze.

Diseases and pests

• Heat and drought damage: Brown leaf edges and curling leaves in summer. Move it somewhere cooler or shadier, water with rainwater and apply a thick mulch.
• Chlorosis: Yellow leaves with green veins on soil that is too chalky. Acidify the soil with needle mulch and leaf mould and water with rainwater.
• 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.
• Root rot: Limp, wilting leaves while the soil is wet. Improve drainage with coarse sand or plant on a slight mound.

Through the year

• March: Plant. Cut off dead twigs. Top up the mulch.
• April: Plant. Feed lightly with an ericaceous fertiliser.
• May: Water with rainwater in dry weather.
• June: Flowering begins.
• July: Flowering. In hot weather water and keep cool.
• August: Remove spent clusters. Apply nematodes against vine weevil grubs.
• September: Plant. Collect seed when the capsules open.
• October: Plant. Top up the mulch.
• December: Rest. In frost and dry weather, water on frost-free days.

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 ferrugineum comes from the Latin word for rust and refers to the rusty-brown scales under the leaves.
• Where it grows alongside the hairy alpenrose, which grows on limestone, natural hybrids sometimes occur.
• In the mountains, whole slopes turn pink in June–July thanks to this alpenrose.