A Little Background on Walnuts...

3.10.2023

Walnuts are native to Asia, from Uzbekistan and Iran to south western China. But species of Black Walnut are native to North America, all the way from California throughout the eastern U.S. and south through Mexico. 

As with other horticultural crops (grapes, almonds, etc...), the species evolved in its place becoming adapted (tolerant or resistant) to a variety of diseases and herbivores. When they were brought to North America, they encountered an entirely new environment, and they didn't thrive in their new home. But when grafted onto roots of locally adapted, native species, the roots could thrive where they were adapted, and the scion could thrive to produce the nuts and fruits that were know from the old world.

Persian walnuts (Juglans regia) are grafted to either Northern California Black Walnut (Juglans hindsii) or a hybrid of Persian and Northern California Black Walnut called "Paradox". That's why you see the dark tree trunks and light gray branches in a mature walnut grove.

Persian (aka 'English') walnuts are grown in the U.S. really only in California. They will grow elsewhere (Oregon, Arizona, New Mexico, Texas), but not well enough for commercial purposes.

Just as with apples or grapes, walnuts come in many varieties. In California, nearly all of the commercial varieties were selected locally from seedlings grown from imported nuts or cuttings brought from southern Europe. They were selected for both their commercial traits of vigor, productivity, and disease resistance, but also for their flavor. Most varieties grown in the early 20th century have become obscure, out of favor and forgotten. A few persisted, like Payne, Franquette and Hartley. Here in Lake County, the otherwise unknown Poe is still found here and there.

The first walnut trees at Round River Farm were planted in the late 1800's and a number of them are still here, providing shade at the home or a warren for ground squirrels. By the start of the 20th century, an enterprising horticulturist named Poe began promoting a well adapted local variety that came to be known by his name. Our nonagenarian dean of walnut farming in Lake County, Alex Suchan, told me that he had grafted our orchard trees in about 1960, but that 'old man Poe grafted the big ones'. The first trees likely selected for grafting might have been 20 year old Northern California Black Walnut trees, planted for shade beside the homesteads of white settlers. Now they are enormous, declining trees that still bear a few delicious nuts most years.

That's one tree. It menaces our garage and any car parked under it. In the fall, we warn visitors that small, round and hard projectiles may dent their roof or hood. In the winter, a little snow or wind might bring down a 3 thousand pound limb.