How to Grow Grass Under Walnut Trees

Certain walnut trees, such as black walnuts, produce a chemical called juglone that is toxic to most grass and plants. Almost any type of grass you plant underneath the tree will die in a few months. However, Kentucky bluegrass and blue fescue grasses can thrive beneath black walnut trees. Even though these grass types tolerate the toxic chemicals emitted from the tree, you should still monitor the grass for one growing season to ensure that discoloration or bare patches don't appear.

Spade

Garden fork

Compost

Rake

Ground cover

Hand-pull any weeds surrounding the walnut tree area. Press a spade next to the base of weeds to lift them from underneath.

Break up the soil around the walnut tree with a garden fork. Avoid using a tiller. The walnut tree may have a shallow root system, though most have deep taproots.

Broadcast your blue fescue or Kentucky bluegrass seed in the early fall. You can distribute blue fescue at a rate of 6 to 8 pounds per 1,000 square feet. Kentucky bluegrass can be distributed at 2 to 3 pounds per 1,000 square feet.

Cover your grass seed with 1/2 inch of compost. Rake the compost so it completely covers the grass seed to prevent birds from picking off your seeds.

Water the area thoroughly so the ground is moist. Keep the ground moist for the first two weeks by spraying the area with a mist of water three times a day.

You can grow other types of ground cover underneath black walnut trees such as bee balm, hollyhock, goldenrod and fleabane.

Avoid piling on dirt and planting on top of walnut tree's roots, because it prevents the tree from absorbing ground moisture.