Troubleshooting
Silver Knight heather problems — and how to fix them
Silver Knight heather (Calluna vulgaris 'Silver Knight') 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.
Loss of silver colouring
Silver tones diminish in shade or overly fertile soil. Ensure full sun and avoid nitrogen-heavy fertilisers. The silver is most intense in winter — low-nitrogen, potassium-rich feeds support the best colour.
Botrytis on woolly foliage
The dense woolly hairs trap moisture and can develop grey mould in wet, still conditions. Improve air circulation by not crowding plants, and avoid wetting the foliage when watering. Remove any affected stems promptly.
Winter wet collar rot
Wet weather combined with poor drainage can rot the plant at the base during winter. Plant on a slight mound or in raised beds and ensure the crown is never in standing water. Grit mulch around the base helps.
Prevent silver knight heather problems before they start
Most silver knight heather issues are care-mismatch, not bad luck. Dial in the basics:
Silver Knight heather problems — FAQ
Why is my silver knight heather loss of silver colouring?
Silver tones diminish in shade or overly fertile soil. Ensure full sun and avoid nitrogen-heavy fertilisers. The silver is most intense in winter — low-nitrogen, potassium-rich feeds support the best colour.
Why is my silver knight heather botrytis on woolly foliage?
The dense woolly hairs trap moisture and can develop grey mould in wet, still conditions. Improve air circulation by not crowding plants, and avoid wetting the foliage when watering. Remove any affected stems promptly.
Why is my silver knight heather winter wet collar rot?
Wet weather combined with poor drainage can rot the plant at the base during winter. Plant on a slight mound or in raised beds and ensure the crown is never in standing water. Grit mulch around the base helps.