Black walnut

Juglans nigra

Native range

Native to east and central north America, but grown in southern Britain and western Europe for nearly four centuries.

Provenance choice

Late flushing varieties identified in French breeding programmes or provenances from the northern part of the natural distribution (New England, southern Ontario) should be preferred. A hybrid between black and common walnuts (Juglans x intermedia) is reportedly less sensitive to frost.

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

Generally considered to be more resistant to Armillaria root rot (honey fungus) than common walnut.

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.