Troubleshooting
Castlewellan Cypress problems — and how to fix them
Castlewellan Cypress (x Cupressocyparis leylandii 'Castlewellan') 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.
Seiridium canker
Fungal disease causing patches of dead, brown foliage; remove affected branches promptly and improve airflow.
Honey fungus (Armillaria)
Root rot in waterlogged or stressed trees; no chemical treatment — remove affected stumps and roots.
Excessive size
Grows very fast and can become difficult to manage; clip at least twice a year and never cut back into bare brown wood.
Neighbourhood disputes
High Hedges legislation (UK) applies to hedges over 2 m blocking light; maintain at appropriate height.
Prevent castlewellan cypress problems before they start
Most castlewellan cypress issues are care-mismatch, not bad luck. Dial in the basics:
Castlewellan Cypress problems — FAQ
Why is my castlewellan cypress seiridium canker?
Fungal disease causing patches of dead, brown foliage; remove affected branches promptly and improve airflow.
Why is my castlewellan cypress honey fungus (armillaria)?
Root rot in waterlogged or stressed trees; no chemical treatment — remove affected stumps and roots.
Why is my castlewellan cypress excessive size?
Grows very fast and can become difficult to manage; clip at least twice a year and never cut back into bare brown wood.
Why is my castlewellan cypress neighbourhood disputes?
High Hedges legislation (UK) applies to hedges over 2 m blocking light; maintain at appropriate height.