Nova Zembla rhododendron

Sun

Partial shade or dappled light; morning sun with afternoon shade is ideal. More sun is tolerated in cool climates if the roots stay moist.

Water

Keep the shallow root zone evenly moist but never waterlogged. Water deeply during dry spells, including dry autumn weather before the ground freezes.

Soil

Acidic, humus-rich, well-drained soil, ideally pH 4.5-6.0. Avoid chalk, lime and compacted clay; use a broad raised bed where drainage is poor.

Height

6-8 ft (1.8-2.4 m), sometimes taller with age

Spread

5-7 ft (1.5-2.1 m)

Flowers

Late spring to early summer; rounded clusters of ruby-red to crimson flowers with darker blotches.

Foliage

Evergreen. Large, leathery, dark green leaves retained through winter; leaves may curl and droop in freezing weather.

Growth

Moderate; slower in cold, exposed or less suitable conditions.

Care needed

Medium

• Pollinators
• Cold hardy
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1.6 ft (0.5 m)

2. After 1 year

   2.4 ft (0.75 m)

3. After 2 years

   3 ft (0.99 m)

4. After 3 years

   4 ft (1.2 m)

5. After 5 years

   6 ft (1.7 m)

About 7 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Growth rate

Slow

• Plant with the top of the root ball level with or slightly above the surrounding soil; do not bury the stem base.
• Water the root zone during dry weather, especially through the first two growing seasons; use rainwater if your tap water is hard.
• Apply 2-3 in (5-8 cm) of leaf mould or composted pine bark, keeping it clear of the stems.
• If growth is weak, apply a light dose of rhododendron fertiliser in spring according to the label; avoid late-season feeding.
• Avoid digging around the shallow roots, and shelter the shrub from drying winds and strong winter sun.

Pruning. Prune lightly just after flowering, removing dead or damaged wood and shortening only shoots that need shaping. Spent flower clusters can be snapped off carefully without damaging the new shoots below; late pruning removes next year's flower buds.

Early spring

Check soil moisture, refresh mulch and feed lightly only if needed.

Spring

Plant while the soil is workable and moist, keeping the root ball shallow and watering thoroughly.

Late spring to early summer

After flowering, remove spent clusters if wanted and carry out any light shaping.

Summer

Water deeply during dry spells; drought now can reduce next year's flower buds.

Autumn

Replenish mulch and water well during dry weather before winter.

Winter

Check exposed plants for wind damage; protect young shrubs with a windbreak rather than wrapping the foliage tightly.

• Plant at a woodland edge with ferns and hostas for red flowers above layered shade foliage.
• Use as an evergreen backdrop in a mixed border, allowing room for its mature width.
• Group several in a spacious acidic-soil garden for a strong late-spring display.
• Place near an entrance or path where its flowers can be seen closely, but keep it clear of narrow walkways.

Garden styles it suits: Woodland, Traditional, English country, Grand estate, Pacific Northwest woodland and Japanese.

Plant it with: Japanese maple, Japanese pieris, Mountain laurel, Hostas, Japanese painted fern and Astilbes.

Wildlife: Flowers are visited by bumblebees and other insects, and dense evergreen branches provide shelter for small birds. It is not a native habitat substitute in any of the regions covered here.

• Yellow leaves with green veins often indicate alkaline soil or impaired roots: check soil pH and drainage, avoid lime, and move to a suitable raised bed if necessary.
• Phytophthora root rot causes wilting and dieback in wet soil: improve drainage, avoid overwatering and remove badly affected plants; do not replant into the same wet conditions.
• Vine weevil adults notch leaf edges, while larvae eat roots: inspect plants and use appropriate beneficial nematodes when soil conditions meet the product instructions.
• Winter scorch leaves brown leaf edges or patches: shelter from drying winds and strong winter sun, maintain mulch and water before freezing weather if the soil is dry.

Toxic to people, cats, dogs and horses. All parts, including leaves, flowers and nectar, contain grayanotoxins; ingestion can cause vomiting, weakness, dangerous heart disturbances and, in severe cases, death. Seek urgent medical or veterinary advice after suspected ingestion.

• Catawba rhododendron (Rhododendron catawbiense)

  Has similar broad evergreen leaves and rounded flower clusters, but the species usually flowers lilac-purple rather than ruby red. Leaves alone are not a reliable way to identify 'Nova Zembla'.

Rhododendron comes from Greek words meaning 'rose tree', while 'Nova Zembla' refers to Novaya Zemlya, the Russian Arctic archipelago.

Propagation. Propagate by layering a low branch or by taking semi-ripe cuttings in late summer; cuttings usually need an acidic propagation medium, humidity and bottom heat. Seed will not produce plants true to 'Nova Zembla'.

Accepted botanical name

Rhododendron

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