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Rhododendron 'Hardy Gardenia'
Hardy Gardenia Azalea
Hybrid of garden origin; the double (hose-in-hose) flower form is rare among hardy evergreen azaleas — single-flowered cultivars dominate the trade — which makes this cultivar useful where a double white is specifically wanted
Overview
Rhododendron 'Hardy Gardenia' is an evergreen azalea reaching 2-3 feet (0.6-0.9 m) tall with a spread of 3-4 feet (0.9-1.2 m) and a compact, dense, low-mounding habit. The cultivar carries pure white double (hose-in-hose) flowers 2-2.5 inches (5-6 cm) wide in which the layered petals resemble a gardenia bloom and give the cultivar its common name. Flowers cover the plant densely in May-June; bloom duration is 3-4 weeks. Double-flowered evergreen azaleas that are cold-hardy to USDA zone 6 are rare in commerce — most hardy evergreen azaleas carry single flowers — so this cultivar fills a specific combination of hardiness, color, and flower form. Small elliptic leaves 1-1.5 inches (2.5-4 cm) long are glossy dark green. Growth rate is moderate. Hardy to USDA zone 6. Toxic to pets and humans if ingested. The double petals hold moisture longer than single petals after rain, so the cultivar benefits from good air circulation to reduce the risk of petal blight.
Native Range
Rhododendron 'Hardy Gardenia' is a hybrid of garden origin, propagated vegetatively.Suggested Uses
Used in mass plantings, mixed borders, foundation plantings, and container plantings in zones 6-9 at 3-4 foot (0.9-1.2 m) spacing. The double white hose-in-hose flower form serves specifically where a double white hardy evergreen azalea is wanted — single-flowered cultivars dominate the white azalea market, so the double form gives a texture that those cultivars cannot supply. Containers of 3 gallons (11 L) minimum suit the compact habit. The moisture-holding double petals call for a position with good air circulation rather than tight corners. Toxic to pets and humans if ingested. Also not suited to alkaline soils, full sun in hot climates, or dry sites.How to Identify
Appearance
Size & Dimensions
Height2' - 3'
Width/Spread3' - 4'
Reaches mature size in approximately 5 years
Bloom Information
Double (hose-in-hose) pure white flowers 2-2.5 inches (5-6 cm) wide with layered petals that give a gardenia-like appearance, densely covering the plant in May-June. Bloom duration is 3-4 weeks.Detailed Descriptions
Flower Description
Pure white double (hose-in-hose) flowers 2-2.5 inches (5-6 cm) wide with layered petals that recall a gardenia; densely covering the plant; May-JuneFoliage Description
Glossy dark green leathery leaves; small elliptic 1-1.5 inches (2.5-4 cm) long; evergreen year-roundGrowing Conditions
Sun Requirements
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
Care & Maintenance
Care Guide
Grows in partial shade in moist, well-drained, acidic soil at pH 4.5-6.0. Hardy to USDA zone 6. The double petals hold moisture longer than single-flowered azaleas after rain, so good air circulation around the plant reduces the risk of petal blight developing on wet flowers. Mulch the root zone 2-3 inches (5-8 cm) deep with pine bark, pine needles, or oak leaves to hold moisture and protect the shallow root system. Toxic to pets and humans if ingested.Pruning
Prune lightly after flowering to shape if wanted. Avoid pruning after July — next year's flower buds form in summer and are removed by late-season cuts.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
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D
summer
Maintenance Level
lowContainer Growing
✓ Suitable for container growing
Minimum container size: 3 gallons