Black Walnut Toxicity

November 21, 2016

Melinda's Blog is brought to you by American Transmission Company.

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:  Woodland wildflowers and ferns are just a few options for creating beauty beneath a black walnut. And include a few other shade tolerant plants like coral bells, Canadian ginger and lungwort.

For more gardening tips, how-to videos, podcasts and more, visit