I have a beautiful old tree in my front yard growing on an incline. Over the years the root system has spread out and on the downslope they are sticking up out of the ground several inches. It ends up being a pain to mow around and it spans about 15 feet in circumference around the tree so weed wacking it becomes burdensome. Someone suggested I build a little retaining wall from stone or ? And cover the roots with topsoil and plant something in there. Does that sound like a reasonable idea, will it interfere with drainage, anybody got any other ideas. 2 lawnmower blades later I am trying to prepare for the coming season, Thanks!

Anytime you add soil to the surface above a root system you compromise the tree. In your case there may have been erosion that helped expose the roots. I would not add nore than an in or two of soil above the surface of the root.

How steep is the slope? Is grass still growing well? I have cut exposed roots off silver maple and osage orange trees without hurting them.

The grass cover over the tree roots has probably been eroded by weather, but they also supply the tree with a good healthy supply of oxygen. If you cover them with soil, you could suffocate the tree. Instead, I wonder if you could put an inch or two of mulch inside the dripline of the tree. You could put bricks or something around it to define this area and just mow around the boundary. If you do opt for soil, then the coarsest top quality soil that you can get and definitely keep it below 2 inches.

I say, why mess with mother nature? Make a barrier of some kind and let it grow wild under there. You could try adding some ferns (which don't have deep roots) into the area, and I would sprinkle a mixture of seeds of other shallow rooted shade plants, such as purple coneflower, lobelia, coral bells and columbine. If there are areas less full of roots, plant day lilies. It could be a really beautiful site!

Didi

You can place soil over the roots of trees with no adverse effect. Certainly better than chopping them up with a mower blade. What you don't want to do is install a lot of heavy, clay soil. Both water and oxygen are necessary for a tree to have healthy roots. You can build a beautiful stone wall on the down hill side, backfill it with good, sandy, loamy soil that has plenty of air in it. Generally grass and shade don't go together and your soil has both eroded away from the lack of sod and the roots have grown healthier in size.

Trees don't really care about the weight of something on the soil around them as much as they care about the surface being modified or compacted in such a manner that air and water penetration is limited. Parking a car under a tree repeatedly for example will compact the soil to the point it might as well be asphalt.

On the other hand sometimes it is necessary to raise the level of soil around a tree three feet or more. To save the tree, place large rock, 6" or larger around the root zone, build a stone tree well to keep the soil off the trunk of the tree, install some 2" or 4" pipe into this layer of stone so that air and water can reach the original grade. Install filter fabric over the stone and then add topsoil to the desired new height. By doing this you are still allowing air and water to reach the original soil level. This is not always 100
% successful but if properly installed and maintained good success is usually occurs.