GardenWizzPlant Care Card
Rhododendron arborescens
Rhododendron arborescens · Shrub
Hardiness
H6 Hardy — very cold winter (to −15 to −20°C)
Position
Full sun, Partial shade
Height × Spread
2.4–5.5 m × —
Soil
moist but well-drained, leafy, humus-rich acid soil
Toxicity
Harmful if eaten. Contains andromedotoxins (grayanotoxins). Symptoms include depression, vomiting, diarrhea, difficulty in breathing, coma, drooling, burning sensation in mouth, muscular weakness, weak vision, bradycardia, hypotension.
The Gardening Year
J
F
M
A
M
J
J
A
S
O
N
D
🪴 Plant out
🌸 In flower
Watch out for
Powdery mildew: Tolerate unless severe; improve air circulation and avoid overhead watering to reduce humidity.
Bud blast: Remove and destroy infected buds promptly if practical to prevent spread.
Vine weevil: Use nematode treatments in autumn or apply biological controls like Steinernema carpocapsae.
Silver leaf: Prune out infected branches well below the visible symptoms and destroy them immediately.
Pieris caterpillars: Hand-pick caterpillars early in spring or use biological controls like nematodes.