Gumpo White azalea

Sun

Partial shade, ideally morning sun and afternoon shade. Avoid hot reflected sun and exposed, drying sites.

Water

Keep the root zone evenly moist but never waterlogged. Water during dry spells, including winter dry spells when the ground is not frozen.

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

1-2 ft (0.3-0.6 m)

Spread

2-3 ft (0.6-0.9 m)

Flowers

Late spring to early summer; large, ruffled white flowers, sometimes with small pink markings.

Foliage

Evergreen. Small, dense, dark green leaves that remain through winter; some older leaves may drop in autumn or cold weather.

Growth

Slow

Care needed

Medium

• Pollinators
• Heat tolerant
• Low allergen

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

Difficulty

Moderate

Toughness

Needs looking after

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

1. Planting day

   1.5 ft (0.45 m)

   full size

About 8 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 crown.
• Water deeply when the upper soil begins to dry, especially during the first two growing seasons.
• Maintain 2-3 in (5-8 cm) of pine bark or leaf mould mulch, keeping it away from the stems.
• If growth is weak, apply a modest amount of azalea fertiliser in spring according to the label; avoid late-season feeding.
• Use rainwater where possible if your tap water is hard, particularly for container plants.

Pruning. Prune lightly just after flowering to shorten stray shoots and remove dead or damaged wood. Avoid routine shearing or pruning later in the season, which removes developing flower buds.

Early spring

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

Spring

Plant while conditions are mild, keeping the root ball shallow and watering it thoroughly.

Late spring to early summer

Enjoy flowering, then prune only where shaping is necessary.

Summer

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

Autumn

Check moisture before winter and replenish mulch without covering the crown.

Winter

Shelter container plants from drying winds and prolonged root freezing; water during frost-free dry spells.

• Plant along the front of a woodland border with ferns and hostas for contrasting leaf shapes.
• Repeat in small groups beside a shaded path to create a low, flowering edge.
• Grow in a broad container filled with ericaceous potting mix for a courtyard with alkaline soil.
• Combine with other white-flowered, shade-tolerant plants in a white garden.

Garden styles it suits: Japanese, Woodland, White garden, Traditional, Small-space and Southern.

Plant it with: Japanese pieris, Japanese maple, Hosta, Japanese painted fern, Camellia and Lilyturf.

Wildlife: Flowers may attract bees, though this cultivated azalea is not a substitute for locally native shrubs that support a wider range of insects.

• Azalea lace bugs cause pale stippling on leaves: reduce drought stress and excessive sun, inspect leaf undersides, and use an insecticidal soap labelled for azaleas if needed.
• Phytophthora root rot causes wilting and root decay in wet soil: improve drainage and remove badly affected plants; do not replant into the same waterlogged conditions.
• Yellow leaves with green veins often indicate alkaline soil or water: test soil pH and use an ericaceous container mix if the ground is unsuitable.
• Petal blight produces watery spots and rapidly collapsing flowers: remove affected blooms and fallen petals, and avoid overhead watering during flowering.

All parts are toxic if eaten by people, cats, dogs and horses. Grayanotoxins can cause vomiting, weakness, dangerous heart effects and potentially fatal poisoning; seek urgent medical or veterinary advice after ingestion.

• Gumpo Pink azalea (Rhododendron 'Gumpo Pink')

  Has a similarly compact habit and late flowering season, but its flowers are predominantly pink rather than white.

• Delaware Valley White azalea (Rhododendron 'Delaware Valley White')

  Usually grows substantially taller and flowers earlier in spring, with a less compact habit than Gumpo White.

Rhododendron comes from the Greek words for 'rose' and 'tree'.

Propagation. Take semi-ripe cuttings in summer and root them in a moist, free-draining acidic medium under high humidity. Low branches can also be layered; seed will not reliably reproduce the cultivar.

Accepted botanical name

Rhododendron

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