Walnut Guild 🌳
A large black walnut tree lives in the back yard.
I would like to find California native companion plants for it, but have had a difficult time.
Something about the soil makes me think it's poor. It's clay to begin with, but also full of gravel, construction debris and covered by barrier plastic and pea gravel, pavers and bricks in many places. Few things grow well.
The walnut and neighboring buildings cast the yard in shade. California is frequently in drought, so it's dry. I've recently learned walnuts are allelopathic, releasing the toxin juglone. Fwiw, neither an arborist we consulted regarding the health of the walnut, nor the city arborist, expressed concern about juglone toxicity wrt other trees in the yard.
The Black Walnut Dispatch inspires me to take and share notes so we might all learn together.
The permaculture discipline has also been helpful, not least because it has many handy phrases like guild (recreations of plant communities found in nature) and companion plants (symbiotic or mutually supportive), and concepts like a seven-layer garden and soil building.
I've found Gaia's Garden by Toby Hemenway a concise introduction to permaculture, and it even has an in-depth description of a walnut guild!
Paul Stamets, a hero, is a fan of permaculture and proposes a Stametsian Model with an eighth layer for fungi.
Las Pilitas Nursary is a rich source of native plant and permaculture information. CNPS also enables us to search shade plants by zipcode. Lists of juglone-tolerant species abound, eg 1.
So, the challenge is: build a juglone-, drought- and shade-tolerant California native guild around the walnut.
Update 5/22/18
Due to decay in the base of the trunk, as indicated by a large hole in the side and saprophytic oyster mushrooms growing opposite the hole Spring 18, and confirmed by several arborists, we had to cut our beautiful walnut down ðŸ˜
This is a significant change for the yard, so I've generalized the plant list that used to be here and moved it to a post focused on coastal sage scrub permaculture.