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Rhododendron luteum

yellow azalea

Ericaceae

Caucasus, northeastern Turkey, eastern Europe

Attracts Pollinators Attracts Butterflies Deer Resistant Fragrant (strong)

SunFull Sun – Part Shade

WaterMedium

HardinessZones 5–8

Overview

Rhododendron luteum is a deciduous, suckering shrub reaching 6-12 feet (2-4 m) tall and wide, forming open thickets over time. The oblong, pointed leaves are 2-4 inches (5-10 cm) long, soft-hairy and sticky-edged, mid-green in summer and turning shades of red, orange, and purple before falling. Funnel-shaped yellow flowers 1.5-2 inches (4-5 cm) across open in rounded trusses in May, before or as the leaves expand, and carry a strong sweet scent. The flowers have long, projecting stamens and sticky, glandular hairs on the outside. Globe-shaped seed capsules follow. Growth is upright and twiggy, spreading by suckers into broad clumps. All parts contain grayanotoxins, and nectar taken by bees can produce toxic honey.

Native Range

Native to the Caucasus, northeastern Turkey, and parts of eastern Europe, growing in damp woodland, scrub, and stream sides on acidic soils. Widely planted in gardens elsewhere, it has naturalised locally in Britain and western Europe, sometimes forming dense stands.

Suggested Uses

Used in woodland gardens, shrub borders, and acidic-soil plantings, spaced 6-10 feet (1.8-3 m) apart, and as an informal screen or thicket. The scented spring flowers and autumn leaf colour suit naturalistic settings. Its suckering spread and toxic parts limit its use in small or grazed areas.

How to Identify

Recognised by the deciduous habit, strongly scented yellow funnel-shaped flowers 1.5-2 inches (4-5 cm) across in May, and sticky, glandular hairs on the flower tube. The hairy, oblong leaves turn red and orange in autumn. The yellow flowers and deciduous leaves separate it from evergreen rhododendrons and from pink-flowered deciduous azaleas.

Appearance

Size & Dimensions

Height6' - 12'

Width/Spread6' - 12'

Colors

Flower Colors

yellow

Foliage Colors

green

Fall Foliage Colors

red

orange

purple

Bloom Information

Bloom Period

~3 weeks

Spring

Flowers in May, before or as the new leaves appear, over about 2-3 weeks. Bloom is earlier in mild areas and later in cold or northern gardens. The scent carries on warm, still days. Late frosts can damage open flowers and shorten the display.

Detailed Descriptions

Foliage Description

mid-green, turning red, orange and purple in autumn

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-8 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range4.5 - 6.0(Acidic)

357912

Soil Types

loam peat sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

5-10 years

Care & Maintenance

Care Guide

Grows in full sun to partial shade on moist, acidic, humus-rich, well-drained soils and fails on chalky or alkaline ground. It needs steady moisture through summer but does not tolerate waterlogging. The shallow roots benefit from a mulch of leaf mould or bark, which keeps the soil cool and damp. Powdery mildew can affect the leaves in late summer in dry conditions. The plant suckers freely and can spread into a wide thicket. Vine weevil grubs sometimes damage the roots of container plants.

Pruning

Prune after flowering if size needs limiting, cutting back to a bud or branch fork. Remove suckers at the base to stop the clump widening. Old, congested plants tolerate hard renovation pruning in late winter, regrowing from the base over a season or two.