What happens to tree roots after stump grinding, and will the stump grow back?

Does stump grinding remove the roots?

A stump grinder removes the stump and the large lateral roots close to it. Iowa State Extension says these machines “chew away the stump and any large lateral roots, typically down 8 to 12 inches.” Everything below that depth, and the thinner roots that spread farther out, stays in the ground.

That is how most people expect grinding to work, and it explains most of the questions in this guide. A ground stump leaves a hole full of wood chips. It does not leave a root-free yard. The roots that remain are part of the same wood that was above ground. They will break down on their own schedule.

Here is what the pieces look like after grinding:

Cincinnati Stump Grinding grinds tree stumps in Dayton, Cincinnati and Northern Kentucky. The business describes its machine as “powerful” and “turf-friendly” and says it will “reduce your tree stump to wood chips quickly.” Grinding roots farther from the stump is a different job. Ask about it when you request your free estimate.

Do the roots die after grinding?

Often the roots break down over time, but no extension page we found says every root dies, or how soon. The best-supported fact is about speed. Purdue Extension says “it can take several years to fully decompose the stump unless it was ground very deeply or removed with an excavation machine.” Iowa State adds that natural decay depends on soil moisture, the amount of wood-decay fungi and the tree species, and “the process can take 10+ years.”

Roots can also stay alive for a while after the trunk is gone. Ohio State University Extension makes this point about ash trees killed by emerald ash borer: “EAB only kills the above-ground portion of their ash hosts.” New growth then “could and did resprout from the base.” That page is about ash, so it does not prove the same thing for every species. It does show that roots and stump bases can live after the visible tree is gone.

For the full answer, read Do roots die after stump grinding?.

Do the leftover roots cause problems?

Most leftover roots are slow to rot and quiet. A few situations make them matter. The table lists them, along with what the sources say.

Read more on this in Should you remove roots after stump grinding?. If you plan to replant, see Can you plant a tree after stump grinding? and Can you plant grass after stump grinding?.

Will a stump or root sprout again?

It can, and it depends on the tree. Iowa State Extension says “some stumps will resprout after the tree is cut down.” Purdue says sprouts “may be generated due to the roots acting as energy storage for the tree.”

Ash is the local example. Ohio State University Extension says “ash regeneration became evident in southwest Ohio as early as 2008 with regrowth from the basal portions of dead trees and stumps forming multi-stemmed ‘bush ash.’” The emerald ash borer arrived in Hamilton County in 2007, and the same page says the new stems were attacked once they grew large enough to support larvae.

The terms used for new growth are worth knowing:

• A stump sprout grows from the stump or its base.
• A sucker grows from a root, away from the stump.
• Resprouting is the general word for either one.

Penn State Extension warns about one case in its cut-stump video. Treatments on a stump of tree of heaven control the stump, “but not the roots, and the tree will resprout prolifically.” The video says that tree is an exception, because the herbicide moves down to the roots poorly. Do not read that as a rule for every species. Read the full guide at Will a stump grow back?.

What do extension pages say about stump killer?

Extension pages describe herbicide as a way to reduce resprouting, not as a way to remove a stump. Iowa State says “while herbicides can be used to prevent resprouting, they are not beneficial for promoting decay of the stump.” It also says commercial stump removal products “tend to simply be a form of fertilizer (often potassium or sodium nitrates), so regular fertilizers can work just as well.”

Herbicide labels differ by product, so follow the product label on every step. Iowa State says that herbicides “only need to be applied to the living cambium tissue, which is in a ring just below the bark,” and that if sprouts appear after treatment, you “cut the sprouts and reapply the herbicide.” Penn State adds that treatment timing matters and that cut-stump treatments “should not be applied in spring when upward sap flow renders them ineffective.”

Details are in Does stump killer work?. For other do-it-yourself options, see Does Epsom salt rot a stump? and Can you burn a tree stump?.

Do tree stumps attract termites?

A rotting stump is wood in the soil, and termites eat wood. The University of Kentucky Department of Entomology says what that means for your house: “Swarms of termites emerging from tree stumps, woodpiles, etc. out in the yard are not necessarily cause for concern, and do not automatically mean the house is infested.”

The same page adds the warning sign: “if swarmers are emerging next to the foundation or from abutting porches or patios, there’s a good chance the home is infested as well.” The sister publication says “where practical, remove stumps and dead roots around and beneath buildings.”

Ohio State University Extension notes that “control of subterranean termites requires certified professionals.” If you see winged insects indoors, mud tubes or damaged wood, ask a licensed pest professional to inspect. The full explanation is in Do tree stumps attract termites?. A subterranean termite and a carpenter ant look alike in swarm season, so do not guess.

Why do mushrooms grow on old stumps?

Mushrooms are the fruiting bodies of fungi that break down wood. Illinois Extension says “spring and late summer/early fall are the prime times for decay fungal growth to be visible as mushrooms of all sizes, shapes and colors.” The same page says that where an ash was removed, mushrooms come up in the lawn “as the decay follows the path of the tree root,” and that “this happens even if the stump was ‘ground out.’”

Penn State Extension covers common fungi in landscape mulch. It says those fungi “are not harmful to landscape plants, and no known health hazards are associated with them unless they are eaten,” and that mushrooms “may be poisonous if eaten.” That page is about mulch, not stumps. It is still the clearest extension statement on whether mushrooms in wood debris hurt plants.

If mushrooms grow on the trunk of a tree that is still standing, treat it differently. Illinois says a mushroom on a trunk “suggests that the internal dead woody tissue has been invaded.” Ask an ISA Certified Arborist to look at it. See Mushrooms on tree stumps and the glossary entry for stump fungi.

Should I remove surface roots?

Usually not by cutting. University of Wisconsin Extension says “damaging these roots, such as by hitting them with a lawn mower or trying to prune them away can seriously affect the health of the tree.” Its options are to add “a shallow layer of topsoil” and cover the roots by “about a half inch,” or to “eliminate the grass and cover the area with mulch such as shredded wood.”

The same page warns that “applying too much soil over the roots of a tree can suffocate them and cause tree damage or death.” Surface roots belong to a living tree. They are not the same as roots left behind by a stump you had ground. Read Exposed surface roots before you cut anything.

How long do roots take to rot?

No source we opened gives one number for all trees. The ranges in the sources are:

Soil moisture, the amount of wood-decay fungi and the tree species all change the timeline, according to Iowa State. For details on how decay works, see the glossary entries for natural decay and lateral roots.

What should I do next?

Match the question to the step.

1. You want the stump gone. Grinding removes it above ground and the large lateral roots. Read Stump grinding vs stump removal if you are comparing it with digging.
2. You want to know if the roots are a problem. They rarely are. Check the table in the section on leftover roots, then decide.
3. You see sprouts. Cut them early. Follow the product label for any herbicide, and use the pages above for timing.
4. You see termites or swarmers. Call a licensed pest professional. Do not rely on a web page.
5. You see mushrooms. Check where they grow. Stump or lawn is usually just decay. Trunk of a standing tree needs an arborist.

Before you dig anywhere in the yard, read Before you grind: 811, tree lawns and permits.

Next step

If you are ready to remove the stump, read How stump grinding works for what to expect, or see the stump grinding service. Call (513) 587-6772 or send photos for a free estimate.