Ash (AH)

Fraxinus excelsior

Native range

Native to the British Isles and much of western Europe except the far north.

Provenance choice

Material from good quality British stands should be preferred with provenances in northern France as an alternative in southern Britain.

Site requirements

Has intermediate shade tolerance when young but needs early thinning for good growth. The species is cold hardy and moderately tolerant of exposure, but is susceptible to late frost damage which can cause forking. This is a very site demanding species. Grows best on moist, well-drained deep and rich soils with a high nitrogen content, and often overlying calcareous bedrock; requires pH values of 5 or above. Nutrient poor dry and waterlogged soils should be avoided.

Pests and pathogens

In Britain, ash trees can suffer from a variety of root and butt rots that can cause late flushing, thinning foliage and decline leading to eventual death. Ash can also suffer from a condition called ash dieback, involving the death of scattered twigs, branches or limbs, especially in the eastern drier parts of the country. It is commonly affected by ash bud moth (Prays fraxinella), which causes wilt and dieback of some small twigs.

Mortality of ash has been increasingly observed in European countries during the last ten years associated with a new species of fungal pathogen, Chalara fraxinea. Another threat comes from an exotic beetle pest (emerald ash borer) that causes significant damage to North American ash trees following its recent introduction into that region. Although there is no evidence that this insect has arrived in the UK, the increase in global movement of imported wood, wood packaging and dunnage poses a significant risk of its accidental introduction.


A warming climate should increase the productivity of ash on suitable sites in northern Britain.