Not sure about dog proof, but here's some things that are suppose to grow under and around black walnut. astilbe, bee balm, begonia, bellflower, bergamot, bloodroot, Kentucky bluegrass, spanish bluebell, virginia bluebell, bugleweed, some chrysanthemum, coral bells, cranesbill, crocus, shasta daisy, daylily, dutchman's breeches, ferns, wild ginger, glory-of-the-snow, grape-hyacinth, herb robert, hollyhock, hosta, hyacinth, siberiean iris, jack-in-the-pulpit, jacob's ladder, jerusalem artichoke, lamb's ear, leopard's bane, lungwort, mayapple, merrybells, morning glory, narcissus (some) pansy, peony (some), phlox, polyanthus primrose, snowdrop, solomon's seal, spiderwort, spring beauty, siberian squill, stonecrop, sundrop, sweet cicely, sweet woodruff, trillium, tulip, violet, virginia waterleaf, winter aconite, zinnia.

It is not just the shade of BW tree, There is more. BW tree releases a chemical, which I think is called Joglanole. This chemical exists in all part of the tree from root, to bark, and leave. Additionally, the root line might be even bigger than its canapy. I have read an illinois univrsity study about this, which has listed plants that are compatible and others that cannot thrive. Over the years, BW would contaminate the soil to the extent that you cannot change it. And there is no chemical to nullify that joglanole. Last year I planted tomato in a soils brough from another location. Tomato plants weredoing fine. But when thir roots reached the existing soil, they wilted and died' But there are a lot of things that are gowing just fine under BW tree, Automn olive, hawthorn, creeping myrtle (vinca?), something from hosta family, honeysucle,..But maple, pine, BW own seeding will not survive.

I haven't tried those under a walnut, but I know from experience that Chamaecyparis, Cryptomeria, Cornus florida, C. kousa, Clerodendron bungei, Choisya ternata, & Eleagnus pungens will thrive in part shade under a black walnut.

I use containers that range in size from 2 liter soda bottles to 30 gallon tubs. I have begun this year to build some SWC's, but will have most of my tomatoes in 18 gallon plastic pots with two plants per pot. A few years ago, a neighbor took down a very old and very large (30 inches in diameter) black walnut tree. I tried to get some of the main trunk, but after a lot of "begging", was finally told that he had sold it all but that if I wanted, I could have the stump. As he told me I'd have to dig it out, he was grinning in that way that makes me wander if he was laughing at me. After digging for "a while", I finally used my truck to jerk the thing out of the ground. I smiled and as he helped me load it, I thanked the "gift horse" for being so generous. He laughed and asked me what I could possibly do with that "worthless" stump. I just smiled and said, "I might get a bowl or two turned out of some of it.". He just shook his head and laughed again. I just kept smiling as I drove off with the bed of my truck covered with the best part of the tree. Ted