There are several plants, shrubs, vines and trees which can be grown closer to juglone. Such species include marigold, summer phlox, morning glory, squash, plum, corn, carrots, pansy, melons, cherry and nectarine. However, you have to keep monitoring the seedlings thoroughly to see for any symptoms of toxic infection.
As for the plants sensitive to juglone, you have to plant them at a safe distance from the drip line of the black walnut tree, so that they can thrive without being affected by toxic substances. An 80-foot radius away from the drip line is considered to be ideally safe for growing sensitive plants.
You should make a visible barrier between the black walnut tree and the sensitive plants you are to grow. A rock wall can be made for this purpose, demarcating the safe area for your garden and minimizing any possible toxic effects from the roots of the tree.
You have to construct a raised bed outside the 80-foot radius by arranging rows of bricks. Landscape timbers, railroad ties or any other suitable material can also be used as an alternate to the bricks. It is further advised to lay down a barrier of plastic or plywood to prevent the walnut roots form penetrating the container garden.
Fill the raised bed with good quality potting soil to plant seedlings. It is better to use natural compost instead of synthetic fertilisers for your plants in the beds.
Prevent leaves, twigs and nuts of walnut tree from entering the raised bed. This might leach some juglone into the soil and you should regularly rake any debris from the black walnut tree.
Make sure your raised bed is doesn’t get dry and keep watering the plants regularly.