Minimizing Root Competition
Some trees, such as maples and elms, naturally produce a great mass of surface roots. Other trees that are normally deep-rooting will often produce quantities of surface roots when planted in a garden situation merely to take advantage of the frequent, shallow irrigation from sprinklers. In either case, too many roots in a planting area beneath trees causes problems for smaller plants. Often the competition for nutrients and water is so rigorous that the smaller plant either dies or ply never grows. Here are some ways to deal with this.
Choose plants that compete well with the tree roots. Your local nursery people can . advise you on these choices. A watering and feeding system that places the water and nutrients directly to the area around these plants is another obvious way to help them compete.
Root pruning outside the drip line of the tree can also help. This is done by digging a 16 to 18-inch trench, cutting and clearing the planting area of tree roots. After this is done once, it’s easier in subsequent years. If you lay a sheet of black plastic against the side of the trench as a further deterrent to invading tree roots, you may be able to skip a year or two.
It’s important to remember that as you improve the soil for the plants you are adding, you are also encouraging the tree roots to grow into that area.
If all you really desire is a little color under an aging shade tree, and the previous suggestions sound like too much work, there’s yet another solution. You can build a simple portable deck, and place containers of colorful, shade-loving annuals on top of it. This can be especially useful under oak trees with a susceptibility to oak root fungus. One of the major deterrents to oak root fungus is keeping the surface soil as dry as possible. With a portable deck, and a few containers, you can have your flowers and the oaks too.
