In no case should mulch or chips be touching the tree itself. Thin layers of shredded mulch are acceptable. As they break down, the added organic matter may benefit the tree as well as your other plants. You may add a few inches of large wood chips, since water and oxygen can penetrate them. You can help us add to this list by emailing your observations to though it is, do not pile soil on top of tree roots in order to create a garden, as you will be suffocating the tree. This is an area that has not been studied enough to give us clear planting advice, but this spreadsheet lists some anecdotal observations by Virginia gardeners and naturalists of some plants thriving within a yard or so of a tree. Different tree species may tolerate different understory plants. Trees help each other to grow via underground fungal connections, but they also put out chemicals that inhibit the growth of other plants right next to them, thus reserving the space for their own needs. You may notice that there are few plants in the woods that grow right up against the trunk of the trees. The big problem with them is that although some shrubs and trees will survive in shady conditions, only a few will grow, flower or bear fruit, and fewer still can get by in bone dry conditions. Adding shrubs or other trees is more difficult but can be done if you are careful. Many plants can be found for sale as two inch plugs, which are easily installed and are much less expensive. Trees with damage to over a quarter of their roots may slowly die in some cases such as Tulip Poplars, compaction by heavy machinery is enough to threaten them. Half of the trees’ roots grow within the top six inches of soil, and most of the rest are within the top two or three feet. A rule of thumb, so to speak, would be not to cut a root that is wider than your thumb. Great caution needs to be taken to avoid damaging tree roots, which are quite shallow and extend quite a ways beyond the drip line. Weeding requirements are relatively light in the shade compared to in the sun. Connecting them by islands of naturalized areas where fallen leaves are left in place (and not piled deeper than normal) solves these problems. Lawns are not good for trees, given the compaction, lime and other chemicals that may be applied, and the risk of injury from lawn mowers and string trimmers.

If done carefully, adding other native plants can benefit your trees as well as add interest and habitat value to your yard. Special considerations are posed by thin, compacted soil and competition for moisture from tree roots.

Plants for shade