Skip to main content
Rhododendron 'Glacier' (Glacier Rhododendron)
1 / 4
© Katja Schulz from Washington, D. C., USA, some rights reserved (CC-BY) · Wikimedia Commons
Shrubs

Rhododendron 'Glacier'

Glacier Rhododendron

Ericaceae
Garden hybrid origin (B.Y. Morrison, USDA Glenn Dale MD; purest white Glenn Dale azalea; bridges Kurume and Southern Indian types)

At a Glance

TypeShrub
HabitUpright
FoliageSemi-evergreen
Height3-5 feet (0.9-1.5 m)
Width3-5 feet (0.9-1.5 m)
Maturity6 years

Growing Zones

USDA Hardiness Zones

6 - 9
Zone 6Zone 7Zone 8Zone 9
These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →
Frost Tolerancehardy

Key Features

Attracts PollinatorsAttracts ButterfliesAttracts HummingbirdsContainer Friendly
Maintenancelow

Overview

Rhododendron 'Glacier' is a semi-evergreen to evergreen azalea reaching 3-5 feet (0.9-1.5 m) tall with a spread of 3-5 feet (0.9-1.5 m) and a compact, dense, upright to rounded habit. A Glenn Dale hybrid (developed at the USDA Plant Introduction Station, Glenn Dale, Maryland by B.Y. Morrison), it produces single, funnel-shaped flowers 2-2.5 inches (5-6 cm) wide in pure white with a faint green tinge in the throat, densely covering the plant in May. The small, elliptic leaves 1-2 inches (2.5-5 cm) long are glossy medium to dark green. Growth rate is moderate. Hardy to zone 6. The Glenn Dale hybrids were bred to fill the gap between the small-flowered Kurume azaleas (hardy but small flowers) and the large-flowered Southern Indian azaleas (large flowers but tender). 'Glacier' is the purest white Glenn Dale.

Native Range

Rhododendron 'Glacier' is a hybrid of garden origin, developed by B.Y. Morrison at the USDA Glenn Dale station, Maryland.

Suggested Uses

Planted in mass plantings, borders, or foundation plantings at 3-4 foot (0.9-1.2 m) spacing. Pure white. Glenn Dale hybrid. Semi-evergreen. Not suitable for alkaline soils, full sun, or dry conditions.

How to Identify

Distinguished from 'Hardy Gardenia' (also white azalea) by the single (versus double) flowers and the slightly larger size. Distinguished from the Girard azaleas by the white (versus red/pink) color and the Glenn Dale (versus Girard) breeding. The purest white Glenn Dale azalea—single white flowers with faint green throat, densely covering the plant.

Appearance

Size & Dimensions

Height3' - 5'
Width/Spread3' - 5'

Reaches mature size in approximately 6 years

Colors

Flower Colors

white

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~4 weeks
J
F
M
A
M
J
J
A
S
O
N
D
Spring
Single funnel-shaped pure white flowers 2-2.5 inches (5-6 cm) with faint green throat tinge, densely covering the plant, May. Bloom duration 3-4 weeks.

Detailed Descriptions

Flower Description

Pure white with faint green throat tinge; single funnel-shaped 2-2.5 inches; densely covering plant; May

Foliage Description

Glossy medium to dark green; small elliptic 1-2 inches; semi-evergreen

Growing Conditions

Sun Requirements

Partial ShadeFull Sun
Requires 3-6 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
loampeatsand
Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-4 years

Care & Maintenance

Care Guide

Plant in partial shade in moist, well-drained, acidic soil (pH 4.5-6.0). Hardy to zone 6. Semi-evergreen—may lose foliage in cold winters. Mulch to protect shallow roots.

Pruning

Prune lightly after flowering to shape. Avoid pruning after July—next year''s buds form in summer.

Pruning Schedule

J
F
M
A
M
J
J
A
S
O
N
D
late spring

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 3 gallons

⚠️ Toxicity Warning

Toxic to pets and humans