Techniques for Gardening Under Black Walnut Trees
Prized for their valuable lumber, black walnuts are a curse for many home gardeners.
Every part of this tree contains juglone, a substance toxic to many plants. The greatest concentration of the toxic juglone is within 60 feet of the tree. Minimize your frustration by growing susceptible plants outside this zone. The further you move away from the tree, the lesser the concentration of juglone.
Try growing juglone-tolerant plants like hosta, coral bells, arborvitae and ninebark. Check the Internet for University prepared lists of juglone susceptible and resistant plants. These lists are by no means complete, but do provide a good starting point.
Or create a juglone-free raised bed. Try straw bale gardens or build a raised bed lined with water permeable landscape fabric to help slow or prevent the invasion of black walnut roots into the garden.
A bit more information: Wear gloves when harvesting and processing black walnuts. The juice in the green outer covering is a natural dye that will also stain hands, clothes, tools and work surfaces. Remove husks immediately after collecting the nuts. Allow the nuts to cure before removing them from their shells.