California Walnut (Carya californica)
At a glance
- Lifecycle
- Perennial (hardy)
- Exposure
- Full sun
- Frost limit
- −12.2 °C
Cultivation
Prefers a deep moisture-retentive loam in a sunny sheltered position, requiring a good summer for best development. This species is not hardy in the colder areas of the country, it tolerates temperatures down to between -5 and -10°c. Plants are strongly tap-rooted and should be planted in their permanent positions as soon as possible. Trees are late coming into leaf (usually late May to June) and lose their leaves early in the autumn (usually in October). Plants in this genus are notably resistant to honey fungus. Most species in this genus have quite a wide range of distribution and, in order to find trees more suited to this country, seed from the most appropriate provenances should be sought. This species is closely related to J. hindsii. Trees are self-fertile but larger crops of better quality seeds are produced if cross-pollination takes place.
Propagation
Seed - requires a period of cold stratification. It is best sown in a cold frame as soon as it is ripe (a plastic bottle with the top and bottom removed and a wire mesh top fitted to keep the mice out is ideal)
Edible uses
Seed - raw or cooked. Sweet but with a thick shell, the seed is said to have a better flavour than Juglans nigra. It is also used in cakes, pies, biscuits etc. The seed ripens in late autumn and, when stored in its shell in a cool place, will keep for at least 6 months[K].
Material uses
This species is sometimes used as a rootstock for the common walnut, Juglans regia.
Habitat
Not known
Native range
South-western N. America.