Common walnut - Forest Research

Native range

Native to southern Europe but widely planted further north for nuts and timber including in southern Britain.

Provenance Choice

Limited provenance trials have been undertaken suggesting that preferred material should be late flushing varieties identified in French breeding programmes. Unless interested in growing walnuts for the nuts, avoid using material sourced from open grown trees which often have poor form.

Site Requirements

This is a light demanding species which is very vulnerable to spring and autumn frosts. It produces a very high value timber on suitable sites. It is moderately tolerant of exposure. It should be planted on medium to very rich soils of fresh to moist soil moisture; availability of soil moisture is important for good growth in dry spells. Alkaline soils of good rooting depth are also suitable. Very dry, very nutrient poor or very wet soils should be avoided. Trials suggest that the use of nitrogen fixing nurse crops can be beneficial.

Pests and Pathogens

Considered particularly susceptible to Armillaria root rot (honey fungus).

Use

While it is likely to remain confined to lowland parts of Britain, climate warming should increase the range of suitable sites for this species in northern England, Wales, and parts of Scotland.

Common walnut is categorised as a secondary tree species. These are species that have been planted on a much smaller scale than the principal species but are reasonably well understood and have demonstrated their suitability for forestry in terms of stem form, growth rate and hardiness under current conditions and so have potential for wider use in future.