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Can You Compost Black Walnut Hulls?

Can you compost black walnut hulls?  

The mention of black walnut trees makes many gardeners groan, because all of the plants parts, from leaf to root tip, contain a substance called juglone that causes severe stunting of many plants, including tomato. In fall, black walnut hulls become a car-bashing, foot-bruising problem, too. After you harvest the nuts, you're left with that pile of tarry hulls. Is it really safe to compost them? 

Thanks to on-farm research done by Chris Chmiel in Athens, Ohio, the answer is yes. Looking at all the wasted hulls from black walnut processors in his area, Chmiel  launched into a three-year study that showed that a year of composting turned walnut hulls into a soil amendment with some surprising properties – such as an alkaline pH instead of an acidic one. 

Best known for championing the culture of native paw-paw trees, Chris Chmiel grows paw-paws, goats, and makes compost at Integration Acres in Ohio.

— Barbara Pleasant, contributing editor and author of The Complete Compost Gardening Guide