Northern California walnut tree
Planting areas: USDA Zones 4 to 9
Size: 30 to 60 feet tall
Bloom season: April to May
Exposure: Prefers north-facing hills. Can tolerate full sun.
Pruning needs: Remove dead wood as needed.
Water needs: Adaptable to drought conditions.
This is a tree of many common names: Northern California walnut, Hind’s black walnut or Claro walnut. It is native to Northern California, ranging from San Joaquin Valley to the California coastal ranges.
Northern California walnut can be identified by its short bulky, black trunk and the absence of branches for 10 to 40 feet.
Its immense crown can span 60 feet, making it a fantastic shade tree during hot summer months. Its leaves measure one foot long with 13 to 21 leaflets.
This tree is resistant to frost and does not leaf out until late spring when the soil is warm.
The Northern California walnut does best when planted in fertile, lowland soils with high water tables.
Sandy loam, loam or silt loam is best because these types of soils can hold large quantities of water accessible by the tree’s long taproot, which is why Northern California walnut lends itself to dry farming in a commercial setting. (Transplanting larger trees is not recommended because of the taproot.)
This walnut has been a commercially important rootstock for the English walnut, prized for its resistance to nematodes and tolerance of drought conditions.
The Northern California walnut is also allelopathic. It releases the juglone toxin from roots and leaves which can harm other organisms, giving the tree a competitive advantage.
For a private setting, the tree is a great choice to integrate in wildlife gardens, habitat gardens and drought-tolerant gardens.
A majestic shade tree, it produces delicious and nutritious walnuts that can be harvested once a year between October and November.