Catalpa tree - planting underneath
I have what I assume is a common Catalpa tree. It is approximately 7' around at the base and in the area of 30' tall. The tree appears to be in excellent condition. Over the past several years many roots have become exposed - or worked their way up through the soil. Most of these exposed roots are large - several inches in diameter and are within several feet of the trunk. If I am correct, this is not an issue for concern and a natural occurrence for the tree. Can hostas be planted underneath this tree without injuring it? I have roughly 50 hostas to move that are currently located underneath a dying maple tree. My ideal would be to create a bed underneath this tree - or slightly off to one side. Will it harm the tree to have a depth of dirt placed over the roots? If I built a bed around the tree - should I have a well around the trunk where no dirt would touch it? Would the introduction of boulders (small - 6-10") 5 feet or so the perimeter (as bed border) of the tree cause damage? Thank you for any assistance you can provide!
Hennepin County Minnesota
Yes, you can plant hostas in between roots but no, do not fill with soil, build a bed or any of the other items you suggest. 50 may be too many hostas as each time you dig, you are destroying the small hair roots just below the surface that actually supply your tree with moisture and nutrients. You can put organic mulch down, keeping it away from the trunk of the tree. Like a maple, these roots are meant to be at the level they are and covering them with soil or building a raised bed over the root system will lead to its demise as your maple is doing. The roots of a tree are not just by the trunk but spread out far beyond the canopy. A well around the trunk doesn't take care of the roots. Maybe you can share some of your hostas with friends or find a shaded area on the east side of your property for them.