I’ve been studying the front yard in an attempt to improve the landscape without doing a major overhaul. This area is right along the sidewalk to the front door. The biggest problem? Too much lawn and too many mature black walnut trees, that are too lovely to cut down and provide our only shade, but it’s really boring. If you look carefully, you can see the green garden hose outlining the proposed new bed. I picked up about 300 walnuts from this area. Aware that black walnut trees produce a plant-killing chemical called juglone, I began on-line research to learn what plants might survive beneath their canopy.
You see, I’d like to plant some flowering shrubs to add color, texture, screening, and to link the isolated lamp post bed to the nearest walnut trees, with a few perennials and spring bulbs added as well. And, I’d like an evergreen and maybe some clipped boxwood. Sounds easy enough, until one begins to read the numerous articles pertaining to juglone. That’s where my confusion begins because the articles don’t just disagree, many actually contradict one another. “Yews are tolerant,” says one. “Yews are very sensitive,” reports another. “Daffodils do well under black walnuts,” states one author. “Daffodils all died,” bemoans another. Lilacs are okay; lilacs are sensitive. Who to believe?
Apparently not all plants are as sensitive to juglone as others (So they take longer to die, but all eventually will? I’ve yet to find a definitive answer.) Black walnuts produce this chemical to inhibit growth around them. It is in all parts of the tree: leaves, nuts, bark, branches, and roots. Rain carries it from the tree canopy, so the entire area under a tree’s dripline, and any areas where run-off occurs, is affected. Some studies have been done by various universities, but even they don’t seem to agree. Obviously I don’t want to purchase and install a bunch of plants just to watch them die a slow, agonizing death, although some report highly sensitive plants expire rapidly. Is that less painful to watch?
I read some gardeners’ blogs who deal with the problem by planting areas under black walnuts with large potted shrubs and flowers, which they just plan to replace whenever the plant material begins to look pitiful. That sounds like an expensive method to achieve a pretty landscape, but maybe it’s the only solution. Others just give up and leave it bare, but I’m not happy with that option either. With all the information on the internet, finding plant material that works should be easy-peasy, but I’m finding it very frustrating.
Fortunately, the long winter months lie ahead, so I can continue to research and come up with a plan. If any of you have experience growing under mature (they’ve been poisoning the soil for over 50 years) black walnuts, I’d love to hear from you.