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Rhododendron 'Autumn Amethyst'
Autumn Amethyst Encore Azalea
Overview
Rhododendron 'Autumn Amethyst' is a reblooming evergreen azalea in the Encore series, reaching 4-5 feet (1.2-1.5 m) tall and 3.5-4.5 feet (1.1-1.4 m) wide. Single purple flowers about 2.5-3 inches (6-7.5 cm) across open in a spring flush from April to May and again from midsummer into fall. The dark green leaves are 1-2 inches (2.5-5 cm) long and evergreen, bronzing in winter. It is among the more cold-tolerant selections in the group, growing in USDA zones 6 to 10. Acidic, well-drained soil between pH 4.5 and 6.0 is required; foliage yellows with interveinal chlorosis at higher pH. Late spring frost can damage open buds, and the upright form needs more room than dwarf azaleas. All parts contain grayanotoxins toxic to pets and humans if eaten.
Native Range
This azalea is a hybrid of garden origin and does not occur in the wild. Its parentage traces to evergreen azalea species native to East Asia, chiefly Japan, southern China, and Korea.Suggested Uses
Used as an informal hedge, screen, or border backdrop, spaced 4-4.5 feet (1.2-1.4 m) apart. The upright size gives height behind lower shrubs and along building walls.How to Identify
Appearance
Size & Dimensions
Height4' - 5'
Width/Spread3'6" - 4'6"
Reaches mature size in approximately 5 years
Bloom Information
Opens a heavy spring flush from April to May, then reblooms from midsummer through mid-fall, roughly July to October. The fall flush is lighter than the spring display and shifts with summer moisture and heat. Late spring frost can damage open buds and shorten the first flush.
Detailed Descriptions
Foliage Description
Dark greenGrowing Conditions
Sun Requirements
Requires 4-6 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
Care & Maintenance
Care Guide
Grows in part sun and flowers most heavily with 4-6 hours of direct light, with bloom thinning in deep shade. Requires acidic soil between pH 4.5 and 6.0 that drains freely while holding even moisture around its shallow, fibrous roots. Water deeply through the first two growing seasons and during summer dry spells, since drought stress reduces the late-season flush. A 2-3 inch (5-7.5 cm) layer of pine bark or pine straw mulch conserves moisture and maintains soil acidity. Where soil pH rises above 6.0, leaves show interveinal yellowing that calls for an acidifying amendment. Lace bugs and spider mites can stipple foliage in hot, exposed positions.Pruning
Prune within three weeks after the spring flush, before buds set for the later flushes. Light shaping keeps the form even, while hard cuts reduce the following season's bloom. Established plants tolerate cutting back by up to one-third to renew density.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
late spring
Container Growing
✓ Suitable for container growing
Minimum container size: 7 gallons