PlantsRhododendrons→Swamp azalea (Rhododendron viscosum)

Common names:
Give a thumbs up Swamp azalea
Give a thumbs up Clammy azalea
Give a thumbs up Cory azalea
Give a thumbs up Swamp Honeysuckle
Give a thumbs up Rhododendron

General Plant Information (Edit)
Plant Habit: Shrub
Life cycle: Perennial
Sun Requirements: Full Sun to Partial Shade
Water Preferences: Wet
Wet Mesic
Soil pH Preferences: Very strongly acid (4.5 – 5.0)
Strongly acid (5.1 – 5.5)
Moderately acid (5.6 – 6.0)
Minimum cold hardiness: Zone 4a -34.4 °C (-30 °F) to -31.7 °C (-25 °F)
Maximum recommended zone: Zone 9b
Plant Height: 6 to 12 feet
Plant Spread: 6 to 12 feet
Leaves: Good fall color
Flowers: Showy
Flower Color: White
Flower Time: Summer
Suitable Locations: Bog gardening
Uses: Cut Flower
Will Naturalize
Wildlife Attractant: Bees
Resistances: Flood Resistant
Propagation: Other methods: Cuttings: Tip
Other: Tissue Culture
Pollinators: Moths and Butterflies
Miscellaneous: Monoecious


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Posted by ILPARW (southeast Pennsylvania - Zone 6b) on Jan 23, 2018 7:15 PM

One of my customers planted three small plants that she ordered form a mail order specialty nursery in her yard about 2010 near the house and artificial waterfall and pond. They were doing fine until 2017 when I noticed they had yellow leaves and were dying. I am suspecting that the soil of pH 6.5 is not acid enough or that the good quality clay soil is still too heavy for them. I applied some iron sulfate and sulfur to around the plants and we'll see if they snap out of it in 2018. One author says that this species needs truly acid soil. This is a very nice species, similar to the Sweet Azalea that is more common. The tubular funnel-shaped bell white flowers are about 1 inch in diameter with hairy funnels and in clusters of 4 to 9 flowers blooming in July, and twigs are densely velvety brown. Its native range is from southern New England down the coastal plain of the Atlantic into central Florida, plus some spots in the Appalachians and a little west of them, and along the Gulf coastal plain into Louisiana with one spot in east Texas.

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Discussion Threads about this plant
Thread Title Last Reply Replies
spring purple flowering shrub by tofitropic Feb 28, 2018 7:19 PM 11
North American Wildflowers 2016 by flaflwrgrl May 9, 2016 6:55 PM 60

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