One of the major challenges of urban gardening is finding the right space for your garden. Ideally, a space that gets six to eight hours of sun each day, is conveniently located near a water supply, gardening equipment, and the gardener.
I’ve found that spot, just. In my tree-filled yard, it’s the only place big enough and sunny enough to make a go of it. Problem is, it’s flanked by two of the deadliest characters known to gardening: black walnut trees. Over sixty years old, they’re no pushovers. Handsome, but terminally toxic to many of my favorite things including nightshades (tomatoes, potatoes, eggplant), as well as blueberries, blackberries, raspberries, asparagus, and rhubarb, among others.
It’s known as allelopathy, or when a plant exudes chemicals which kill or reduce the growth of surrounding plants. In the case of the black walnut, it’s a chemical called juglone, and it’s most concentrated in the roots. Everything growing within the root zone of my black walnut trees is subject to the effects of juglone, which can cause plants to yellow and wither.
I’ve considered hiring someone “to take care of my problem.” But I can’t bring myself to do it. Planted by my grandfather, they have a place here. And luckily, I prefer raised bed gardening anyway. Besides, the toxicity remains in the soil for many years even after the trees are gone, so cutting down the trees wouldn’t be of much help. Also luckily, many plants completely ignore juglone, apparently, such as melons, beans, beets and even the black variety of raspberries.
I discovered recently when looking into putting a bird feeder at the edge of the garden that sunflowers and their seeds are also allelopathic. So the feeder is going to be put further from the edge of the garden than I’d planned, and the sunflowers I was going to scatter among other flowers are going to have their own spot.
What challenges do you face in your urban/suburban yard?