Black Walnut

Northern California Walnut Tree

By Jutta Thoerner    UCCE Master Gardener

Juglans hindsii 

Size of Tree: 30–60 feet

Bloom description and season: April to May, green catkins

Pruning needs: remove dead wood as needed.

Exposure: North facing hills, can tolerate full sun

Water needs: Adaptable to drought conditions.

Planting Zone: 4-9 USDA

Juglans hindsii is a tree of many common names: Northern California walnut, Hind's black walnut or Claro walnut. It is endemic to Northern California ranging from San Joaquin Valley to the California coastal ranges. There is now only one confirmed native stand remaining and it's listed as seriously endangered by the California Native Plant Society.

The tree is identified by its short bulky, black trunk and the absence of branches for 10-40 feet. Its immense crown can span 60 feet making it a fantastic shade tree during hot summer months. Its leaves are one foot in length with 13-21 leaflets.   This tree is resistant to frost and does not leaf out until late spring when the soil is warm. Transplanting larger trees is not recommended because of its large taproot.  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 long taproot, which is why this tree lends itself to dry farming in a commercial setting. Juglans hindsii has been a commercially important rootstock for the English walnut, prized for its resistance to nematodes and tolerance of drought conditions. The black 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 with delicious and nutritious walnuts that can be harvested once a year between October and November.