The deadly juglone of black walnut trees

The following is by Linn County Master Gardener, Claire Smith:

    The seeder wagon is in place.  The lawn mower towed it out of the shed down to the water way and then with two planks and my favorite son’s strong back we pushed and pulled it to the other side of the ditch.  With the addition of an old wire garden gate staked behind a sapling, a hand pump from my parent’s former home and a rock lined pseudo fire pit filled with Petunias that were on the end-of-season sale, the area reflects the peaceful primitive atmosphere I was striving for.  This is the area I mentioned in an earlier blog that became inaccessible to mow due to last year’s flood.  Hosta, native grasses and prairie perennials will grace the space next year.  We continued our zeroscaping to include a part of the road ditch that I learned is also impossible to mow after the mower and I suffered a close encounter with the culvert.  Now that waterway is filled with large rocks and what was a sloping grassy space is mulched. 

            Hosta will ring the two Black Walnut trees in the roadway ditch.  Hosta is a plant of choice there because I have some that need transplanting and they are not sensitive to Juglone, a chemical secretion from Black Walnut Trees. 

             Discovered in the 1880s, Juglone is produced in the fruit, leaves, branches and root system of several trees with Black Walnuts exhibiting the highest concentration.  The greatest intensity in the soil exists within the tree’s drip line, on an average 50 ft. radius from the trunk of a mature tree.  Plants susceptible to Juglone display yellowing leaves, wilting and eventual death.  Plants sensitive to Juglone include Peonies, Hydrangea, Asian Lilies, and Lilacs.  There are multiple choices that will withstand close proximity to Walnut trees such as most grasses, Phlox, Sedum, Daylilies, Iris and Hosta.

            Now my challenge is to determine plants that are not only resistant to Juglone, but also to the deer population in this neighborhood.  Unfortunately, Hosta is one of the critters’ favorite choices.  They have already decimated the Hosta and Bee Balm in the ditch on the other side of the lane.  A great winter  pastime will be comparison shopping perennials and grasses that are both deer and Juglone resistant as well as low maintenance for those landscapes. 

             I actually enjoy mowing.  And I like the challenge of creating and maintaining flower beds, but the  simple clean lines of zeroscaping does appeal to me.  A few plants and shrubs easily embellish the area without overstating the purpose of low maintenance.

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