I grow heuchera and astilbe under the black walnut tree, Andi. They love it. But I grow roses under there too. There's even a pear tree growing under the black walnut, not more than 12 feet from its trunk, and it produces lots of pears every year. I tend to think of the juglone stories as myths.
Here's a photo I posted in the California forum earlier this year to show how much rain we'd had the night before. Things were just waking up, so there's not that much in the picture, but I'm standing right by the trunk as I take the photo, and you can see camellias, rhododendrons, hydrangeas, ranunculus, azaleas, bearded irises, daylilies, dianthus, and primulas just in this one spot under the tree.
It's a huge tree, by the way. People have told me it's the biggest black walnut tree in the county, so it's not as though the juglone hasn't had a long time to work its "evil."
