Troubleshooting
Rhododendron 'English Roseum' problems — and how to fix them
Rhododendron 'English Roseum' (Rhododendron 'English Roseum') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Chlorosis from high pH
Yellowing of new growth in neutral or alkaline soil. Lower pH with garden sulphur; apply chelated iron as a corrective treatment and switch to rainwater irrigation.
Winter desiccation
Leaf margins turn brown in cold, drying winds. Select a sheltered site or erect a windbreak; anti-desiccant spray applied in late autumn reduces moisture loss.
Phytophthora root rot
Rapid root and crown decline in wet soils. Improve drainage before planting; do not plant in heavy clay without significant soil preparation.
Vine weevil
Larvae feed on fibrous roots causing wilting and death. Apply nematode biological controls in late summer or autumn to moist soil.
Leggy habit with age
Old specimens can become tall and straggly. Renovate by removing one-third of old stems to the base in early spring over three successive years.
Prevent rhododendron 'english roseum' problems before they start
Most rhododendron 'english roseum' issues are care-mismatch, not bad luck. Dial in the basics:
Rhododendron 'English Roseum' problems — FAQ
Why is my rhododendron 'english roseum' chlorosis from high ph?
Yellowing of new growth in neutral or alkaline soil. Lower pH with garden sulphur; apply chelated iron as a corrective treatment and switch to rainwater irrigation.
Why is my rhododendron 'english roseum' winter desiccation?
Leaf margins turn brown in cold, drying winds. Select a sheltered site or erect a windbreak; anti-desiccant spray applied in late autumn reduces moisture loss.
Why is my rhododendron 'english roseum' phytophthora root rot?
Rapid root and crown decline in wet soils. Improve drainage before planting; do not plant in heavy clay without significant soil preparation.
Why is my rhododendron 'english roseum' vine weevil?
Larvae feed on fibrous roots causing wilting and death. Apply nematode biological controls in late summer or autumn to moist soil.
Why is my rhododendron 'english roseum' leggy habit with age?
Old specimens can become tall and straggly. Renovate by removing one-third of old stems to the base in early spring over three successive years.