Do tree roots die after stump grinding?

What happens to roots when a stump is ground?

A grinder cuts away the stump and the large roots next to it, and the rest of the root system stays in the soil. Iowa State Extension says grinders “chew away the stump and any large lateral roots, typically down 8 to 12 inches.”

Think of three zones. The first is the stump above ground and just below it. The grinder turns that into chips. The second is the large lateral roots that run out sideways from the base. The grinder reaches those too, to about the same depth. The third zone is everything else: thinner roots, roots that go deeper, and roots farther out from the trunk. Those stay.

The table shows what each zone looks like after the job.

Cincinnati Stump Grinding grinds tree stumps in Dayton, Cincinnati and Northern Kentucky. Ask about roots beyond the stump when you request your free estimate.

Do the leftover roots die?

Leftover roots lose their trunk, and over time they break down. Beyond that, the sources are careful. None of the extension pages we opened says that every root dies after grinding. None gives a number of days or months for it to happen.

What the pages do say is about decay 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 Extension says natural decay depends on soil moisture, the amount of wood-decay fungi and tree species, and “the process can take 10+ years.”

Your own yard will not match a table. The sources say moisture, fungi and species matter, but they do not rank them or give a formula. Do not expect an exact date.

Can roots stay alive after the trunk is gone?

Yes, in some species, and the local example is ash. Ohio State University Extension describes what happened after emerald ash borer killed ash trees in southwest Ohio: “EAB only kills the above-ground portion of their ash hosts.” Then “this meant new growth could and did resprout from the base.”

That page is about ash, and about a pest that kills the top of the tree. It is not a claim that grinding leaves every species alive. It does show that roots and stump bases can hold life after the visible tree is gone.

Purdue Extension makes a similar point for ground stumps: “Also, sprouts may be generated due to the roots acting as energy storage for the tree.” Purdue’s advice for sprouts is short. “Simply treat them with typical lawn herbicide as needed at the label recommended rates.”

For a closer look at which trees resprout, read Will a stump grow back?. For the pest background, see the glossary entry for bush ash.

How do you know if roots are still alive?

The sources do not describe a test. What a homeowner can see is the signs on top of the ground:

• Sprouts or suckers. A stump sprout or a sucker is new growth from the stump base or from a root. Both mean living tissue is nearby.
• Mushrooms in the lawn. Illinois Extension says that where an ash was removed, “you will see mushrooms coming up in the lawn as the decay follows the path of the tree root.” Mushrooms mean decay is in progress, not that the root is alive. See Mushrooms on tree stumps.
• Soft ground. As roots rot, the ground can settle. Purdue says “the soil should be added to replace the below ground roots and stump.” See Does the hole sink after stump grinding?.

If you cannot tell what you are looking at, an ISA Certified Arborist can inspect it.

Do leftover roots cause problems?

Usually they sit in the ground and rot. They matter in four places.

What if I want the roots gone?

Roots can be dug out by hand or by machine, but extension pages treat that as heavy work. Iowa State describes digging as “very labor-intensive.” Other ways to speed decay are slow. Read Should you remove roots after stump grinding?, Does stump killer work? and Stump grinding vs stump removal. The stump removal glossary entry explains the terms.

Root grinding beyond the stump is a separate question. Ask about it when you request your free estimate.

Next step

For the full picture on roots, regrowth, termites and mushrooms, read Tree roots, stumps and regrowth. Call (513) 587-6772 or send photos for a free estimate.