Roots and Suckers After Stump Grinding: What's Left Underground and What to Expect

After stump grinding, the stump is gone, but the tree's side roots stay underground and break down slowly. Most cause no trouble for lawns or gardens. Some species, such as silver maple, black locust, poplars and tree-of-heaven, send up root suckers from those roots. For most of them, prompt and repeated removal handles it.

Below, you'll find what is actually left underground and which trees tend to sprout. You'll also find what to do about it.

What does grinding leave underground?

Grinding leaves the tree's lateral root system in the ground. The stump grinder removes the stump and the big surface roots it can reach. However, the roots that spread outward as the tree grew stay put. On a mature tree, they can reach well past the old canopy.

These roots no longer have a crown feeding them. So they can't keep growing the way they did. Instead, they break down slowly in place, at a pace set by species, root size, soil moisture and soil life.

For lawns, garden beds and general planting, this rarely matters. Rotting roots don't heave the lawn or harm nearby plants in normal conditions.

What are sucker sprouts and why do they happen?

Sucker sprouts are new shoots that grow from roots left in the ground after a tree comes down. Some species react to losing their crown by pushing stored root energy into new shoots. People call them root suckers or basal sprouts. They can pop up some distance from the old stump.

This is how the species behaves, so it isn't a grinding failure. The roots still hold stored energy that once fed the crown. Suckering is how certain trees try to grow back. Grinding dealt with the stump, but it doesn't reach the wider root system where those sprouts start.

Which trees sucker after removal?

Silver maple, Norway maple, tree-of-heaven, black locust, poplars and staghorn sumac are the common root-sprouters here. Conifers such as pines and spruces rarely sprout from their roots.

Strong suckering tendency:

• Silver maple (Acer saccharinum), a common yard tree that can sprout hard soon after removal
• Norway maple (Acer platanoides), widely planted and prone to suckering after removal
• Tree-of-heaven (Ailanthus altissima), an invasive tree with an aggressive suckering habit
• Black locust (Robinia pseudoacacia), known for stubborn sprouting after removal
• Poplars and aspens (Populus species), which can sprout across a wide root area
• Staghorn sumac (Rhus typhina), which spreads from its roots and suckers after removal

Many other species fall somewhere in between. If you're not sure what you had, a photo or a short description helps. Bark, leaf shape and fruit all narrow it down.

Tree-of-heaven deserves a special note. Penn State Extension reports that established trees send up root suckers as far as 50 feet from the parent tree.

How long does suckering last?

Sprouting is usually strongest soon after removal, then fades as the roots' stored energy runs down. That energy is limited, because no leaves are making more of it. Stubborn species like silver maple can keep going longer. Still, the same rule applies, and the energy runs out.

How do I get rid of sucker sprouts?

For most species, remove sprouts promptly while they're small, and keep at it. Each sprout you take early uses up stored energy without giving any back. In time, the sprouting slows and stops.

Remove them early. Timing matters most. A sprout with weeks of leaves has already sent energy back to the roots. In contrast, a sprout you take at two inches tall hasn't.

Cut or pull at the base. In a lawn, regular mowing handles low sprouts. If a sprout has some height, cut it at ground level instead. Pulling it after rain, when the soil is soft, also takes a short piece of root.

Stay consistent. Regular passes whenever you notice sprouts work better than one big effort followed by neglect.

What to avoid. Don't let sprouts grow large, since that refills the roots. Also be careful with herbicide near plants you want to keep. Suckers can share roots with nearby trees, so a product can travel to plants you didn't mean to treat.

Tree-of-heaven is different. Penn State Extension says cutting it triggers large numbers of stump sprouts and root suckers. Instead, it recommends systemic herbicide aimed at the roots in mid to late summer. If tree-of-heaven was the tree, ask before you start cutting sprouts. Follow the product label, too.

Can leftover roots damage pipes or a foundation?

Grinding stops new root growth from the stump, so the risk of future intrusion ends with the tree. Even so, roots that already reached a foundation, utility trench, irrigation line or patio are still there. They no longer grow, but they don't disappear.

In most cases, rotting roots near a foundation or pipe don't cause new problems. Roots that were already doing damage are different, for example roots inside a pipe or under a lifted slab. Those need a separate evaluation.

What does this mean for replanting?

Leftover roots compete a little with new plants for water and nutrients at first. For lawn and most garden plants, that hardly matters. For a new tree in the old stump hole, though, rotting roots and possible suckers add up. That's one reason planting a few feet away works better. See replanting after stump grinding for how to prepare the spot.

Questions about your situation?

If sprouts keep coming back, or roots sit near something you care about, talk to us. Shawn gives the estimates himself, so you speak with the person who will plan the job. Request a free assessment or call (518) 960-6057. For the full overview, see stump grinding in Dutchess County.