How deep should a stump be ground?

Short answer: 6 to 8 inches below grade is the standard. That is enough to backfill with soil, seed grass, and mow without hitting wood. Go 10 to 12 inches if you are replanting a tree, setting a fence post, or the stump keeps sprouting.

Why six inches is the number

Grass roots in Iowa lawns live in the top four to six inches of soil. If the stump is ground to that depth, there is enough soil above the remaining wood for turf to root, and the wood below is deep enough that it will not push up through the lawn as it decays.

Two inches is not enough. Plenty of cheap stump jobs stop at two or three inches, which leaves a disc of wood just under the surface. The grass comes up thin, the mower catches it, and the spot stays a scab for years. That is the difference between a grind and a "grind."

Depth by what you plan to do

Grass and mowing

6 to 8 inches. Backfill with soil, top it off after it settles, seed it. This is 90 percent of residential jobs.

Replanting a tree in the same spot

10 to 12 inches, and plant slightly off center from the old stump. The old root system is still there, and a new tree planted dead center competes with decaying wood and old roots. Grinding deeper plus a small offset gives the new tree a chance.

Fence posts, mailboxes, small structures

12 inches, or removal. A post needs solid ground, and grinding does not create solid ground, it creates a hole full of chips. If the post goes exactly where the stump was, take the stump and the root ball out.

Species that sucker

Willow, cottonwood, elm and tree of heaven can push shoots from the roots for a season or two. Grinding deeper helps. Some homeowners follow up with a stump killer applied to the fresh cuts, which is a decision for you, not something we apply.

How to tell what you got

Ask the company for the depth in inches, in writing, before the job. "Ground down" is not a number. Then check it yourself: after the grind, the hole should be deep enough that your hand disappears past the wrist when you reach in at the center.

One more thing worth knowing: deeper costs more. It is more machine time and more fill. A company that quotes the same price for 6 inches and 12 inches is not really offering both.

What happens to the hole

The grindings go back in and get raked level, and then they settle an inch or two over the first season. Top it off with a bag or two of soil before you seed, and check it again next spring. That settling is normal and it is why nobody should promise you a finished lawn the same day.