1 / 14

Rhododendron indicum

southern Indian azalea

Ericaceae Southern Japan

Attracts Pollinators Attracts Butterflies Attracts Hummingbirds Container Friendly

SunPart Shade

WaterMedium

HardinessZones 6–9

Overview

Southern Indian azalea is a low, spreading evergreen shrub in the heath family, growing 2-6 feet (0.6-1.8 m) tall and 3-5 feet (0.9-1.5 m) wide, wider than tall with dense, twiggy branching. The small, glossy dark green leaves are 0.75-1.5 inches (2-4 cm) long, lance-shaped, and often turn bronze-red in winter cold. In late spring and early summer it bears funnel-shaped flowers 2-3 inches (5-8 cm) across in shades of red, pink, white, and bicolors, single or in small clusters at the branch tips. Rhododendron indicum blooms later than most azaleas, after the main spring flush has passed, and its flowers vary widely between named forms. It needs acid, moist, well-drained soil and shelter from harsh sun and wind, struggling in alkaline or dry ground. The dense, low habit and late bloom have made it a long-standing subject for bonsai, where it is known as the Satsuki azalea. All parts contain grayanotoxins and are toxic to people and animals if eaten.

Native Range

Native to southern Japan, where it grows on rocky stream banks, wet cliffs, and mountain slopes. Rhododendron indicum has been cultivated in Japan for centuries and is the parent of many Satsuki azalea forms.

Suggested Uses

Grown in shaded borders, foundation plantings, and woodland gardens on acid soil, and widely trained as Satsuki bonsai. The low, spreading habit suits the front of beds, slopes, and large containers. It pairs with other acid-loving shrubs such as camellias and pieris.

How to Identify

Recognized by a low, wide evergreen shrub with small, glossy, lance-shaped leaves and funnel-shaped late-spring flowers at the branch tips. The flowers are large for the leaf size and range across red, pink, and white, often with stripes or flecks. Its late bloom and small, dense leaves separate it from the earlier, larger-leaved Rhododendron spp. hybrids.

Appearance

Size & Dimensions

Height2' - 6'

Width/Spread3' - 5'

Colors

Flower Colors

red

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~4 weeks

Spring Summer

Blooms in late spring to early summer, usually May to June, weeks after most evergreen azaleas finish. Funnel-shaped flowers open at the branch tips, and a single plant can carry several flower colors or patterns in some forms. The late flowering extends the azalea season into early summer.

Detailed Descriptions

Flower Description

red, pink, white

Foliage Description

dark green

Growing Conditions

Sun Requirements

SunPartial Shade

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

loam peat sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

3-5 years

Care & Maintenance

Care Guide

Grows in part shade to filtered sun in acid, moist, humus-rich, well-drained soil with a pH from 4.5 to 6.0. The shallow roots need steady moisture and a cool root run, helped by a mulch of bark, pine needles, or leaf mold. Hot afternoon sun and dry or alkaline soil scorch the leaves and stunt growth. It needs little feeding beyond an acidic fertilizer after bloom, and lime or hard water harms it. Plants are shallow-rooted and easy to move when young, and they take well to shaping. Cold below about 5 F (-15 C) can damage buds and stems at the edge of its range.

Pruning

Pruning and shaping are done right after flowering, before next year's buds form in summer. Light tip pruning keeps the dense habit and suits the plant to bonsai and clipped forms. Cutting later in the season removes the coming year's flower buds.