When you've ground up tree stumps in your yard, don't just throw the material away. Instead, turn it into landscaping material for your yard. Options include using the ground-up wood as mulch or even using it to create paths in your yard.
Installing Wood Chips for Paths
If you already have established paths of bark or tree mulch throughout your yard, simply spread 4 inches of the ground-up stumps' fresh wood chips over the existing paths. Make a new path by using a lawn mower or string trimmer to cut grass and weeds as close to the soil as possible where you want a path and then spreading a 4- to 6-inch-thick layer of the wood chips on the area.
Mulching Around Trees and Plants
The material left over from ground-up tree stumps also can be a viable mulch around trees and other plants, helping to keep the soil temperatures more stable, keeping some weeds away and cutting down on evaporation -- thus allowing the soil to retain its moisture, according to a Southwest Yard and Garden article from New Mexico State University Extension/Outreach. The chemicals found in woody plants can kill young plants or prevent seedlings from germinating, according to a Washington State University Extension fact sheet. That factor can actually help when you want to prevent weed growth around established plants. On the other hand, your stump mulch won't be a good addition to newly planted beds.
Ideally, add mulch around established trees and other plants in early spring, before weed seeds have a chance to germinate. If weeds are already established, mow them to a height as close to the soil as possible.
After mowing the weeds, use a shovel to spread a 4- to 6-inch-thick layer of your ground-up stump mulch around established plants. The mulch can take some time to break down and add nutrients to soil. So if you're worried about your plants getting enough nutrients in the meantime, add a 1-inch-thick layer of compost to the soil first, and then lay the stump mulch. Also avoid putting the mulch against the trunks of shrubs and trees or against plant stems because it can cause excess moisture, which invites unwanted pests to attack.
Adding Stump Mulch to Soil
Adding organic matter to soil is generally a good practice. In the case of stump material, however, don't do it -- at least not right away. When mixed with soil instead of placed on top of it, stump or tree mulch can "tie up" the nitrogen in the soil, making it less available for growing plants, according to an Oregon State University Extension Service article.
Composting the Material
If the ground-up stump material came from a tree that was diseased, then compost the material before using it as a topical mulch on any garden area. Likewise, the material that came from the deep parts of a stump probably are mixed with a lot of soil, which doesn't make good-looking mulch. In both cases, create a compost pile for your stump material, and let it sit for about one year before using it. Keep the pile evenly moist, and turn it over about every week to encourage sufficient aeration. After it has decomposed for one year, use the material that came from non-diseased trees in garden beds, but use material from diseased trees as only a mulch and not as a soil amendment.
Burning the Debris
If a tree stump was treated with a chemical to encourage it to decompose, the traditional way to deal with it is to burn the stump following the chemical treatment. If, however, a stump was ground after a chemical treatment, then avoid using the ground-up material in landscaping because it could contain substances that are harmful to plants and wildlife. If you plan to burn the material to get rid of it, check with your fire department or permit offices to ensure you have permission to burn the material.