That is a really common concern, and honestly, the short answer is yes—tree roots can absolutely cause the ground under an outdoor bench to shift and become uneven over time. But it is not something that happens overnight, and there are a few smart ways to work around it so your bench stays stable for years.
Tree roots grow and expand as the tree matures. Shallow roots, especially from species like maples, willows, or oaks, tend to spread out just below the soil surface. As those roots thicken, they push the soil upward. If your bench legs are sitting right on top of that active root zone, you might start to see one end of the bench tilt up or the ground around the legs crack and buckle. The movement is usually slow—maybe a fraction of an inch per year—but after three or four years, a bench that was once perfectly level can become annoyingly wobbly.
Now, does that mean you should not put a bench near any tree? No, not at all. Plenty of people love having a shady spot under a tree, and with a little planning, you can absolutely make it work. The key is to avoid placing the bench directly over the thickest, most active roots. Walk around the tree and look at the ground. Do you see large roots breaking the surface? That is a sign that zone is actively lifting. Move the bench a few feet to the side where the ground is flatter and the roots are less visible or less aggressive.
You can also create a stable base to help deal with minor unevenness. A simple gravel pad, a few flat patio stones, or even a small deck platform under the bench can absorb some of the movement. If the ground shifts a little, you can re-level those stones without having to dig up a whole concrete slab. Concrete can crack from root pressure, so solid poured foundations are usually not the best idea right next to a tree.
Another trick is to choose a bench with adjustable feet or place small shims under the legs. That way, if one side starts to rise by half an inch, you can compensate without moving the whole bench. For heavy, permanently fixed benches, consider sinking some pressure-treated wood or metal post anchors into the soil at least a foot deep. But keep in mind—if you cut through a major root to dig that hole, you can actually damage the tree and make the remaining roots grow more aggressively around the cut. So always try to dig between large roots, not through them.
If you are just setting a freestanding bench on the grass, expect to check it once or twice a year. Sit on it, give it a gentle rock, and see if one side feels higher than the other. If it does, a small flat rock or a rubber shim under the low leg usually fixes it in two minutes. Over time, you may need to move the bench a foot or so as the tree grows. It is a small maintenance task for the pleasure of sitting under a mature tree.
One final thought: tree roots are not the only reason ground gets uneven. Soil settling, freeze-thaw cycles in colder climates, and even animal burrows can cause similar shifting. So if your bench starts to wobble soon after installation, do not automatically blame the tree. Check the soil moisture and look for other signs of movement first. But near a tree, roots are definitely the most likely culprit over the long haul.
So yes, roots can make the ground under your bench uneven, but with a little foresight and a few easy adjustments, you can enjoy a stable, comfortable seat in the shade without fighting nature too much.