I love my black walnut tree. I almost love it as much as I hate it, but it's beautiful.
However, grass refuses to grow around it even though my wife and I are adament about cleaning up leaves and fruit that drops from it.
I live in zone 4b and am wondering what is the best species of grass to grow in the yard that has the tree.
I have tried bluegrass and it started to grow, but maybe I didn't do it right.
Is bluegrass the right species to grow around black walnut trees?
Black walnut gives off juglone, which is a chemical that makes it hard for other plants to grow.
Unfortunately, a quick search indicates that there aren't any native grasses that are juglone resistant, e.g. Mr. Smarty Pants at wildflower.org. Zoysia might work, but it doesn't sound like that's a clear winner either, and it grows best in USDA zones 6-9, which is warmer than where you are.
That site lists some other ground covers that you may want to consider:
You could probably plant an attractive mix of these species underneath your black walnut.
If you're willing to consider something other than grass, Toby Hemenway suggests a walnut "guild" in "Gaia's Garden" on pages 194-195. Species that are suggested are elderberry, hackberry, wolfberry, mulberry, Eleaegnus. Currants, if grown with hackberry, may work under walnut. He also suggests the possibility of tomatoes and peppers, as well as legumes.
I had read that mints like peppermint and spearmint tolerate juglone. So I planted some and they lived but did not spread like they usually do. Normally these become unruly and almost invasive which was what I was hoping for. It would look so much better than just dirt, to me. I have planted hostas and daylilies, they lived but did not come back the next year. I am in zone 5a. I have several woody ornamental I keep far away from the drip line of the trees that have been touted as juglone tolerant, I was waiting for them to get larger and stronger before I moved them closer but now I will never move them close. White fringetree, double mock orange, purple smoke bush are the ones I have and am protecting.
I grow tall fescue and 'merion' Kentucky Bluegrass under black walnut trees, and they do pretty well, if watered during dry weather. They also prefer black walnuts and their hulls to be removed soon after falling.
I seem to recall that bugle is a groundcover that is happy under walnuts. It's a pretty groundcover and it doesn't need mowing. We have it on some slopes that are hard to mow and it has spread happily into the woods. No walnuts, though, but eHow feels they're happy together.
Most grasses should not be affected by the Juglone. If you are having considerable trouble with growing grass, might be too much shade. Fine fescue works better in shade.
Juglone affects plants in the Ericaceae family the most.
Alternatively a number of native species are not affected by the juglone, which I have used.
Dogwoods, Spicebush, Maples (Sugar, Red), Serviceberry, Black Raspberry, Purple-Flowering Raspberry
False Solomon Seal, American Ginger, Joe-Pye weed, Mountain Mint, Black Cohosh, Foam Flower, Goldenrod (Giant, Wreathed), Asters (New England, New York, Smooth)
In Minnesota , I grew Perennial Rey grass , Kentucky Blue grass and Tall Fescue, this worked real well together. I planted it in late September. this combination has covered all the bare spots in the yard and looks good . I watered it every day for 30 min. The area that i spread the seed in was 100 x 40 feet . I bought it at the local farm seed store in bulk . one 25 lb bag was about $120. I raked the area and prepped the dirt before using a hand spreader. I tamped the seed into the dirt then watered it lightly. it took about 2 weeks before the grass started to grow . this year looks even better.
