Q: We have a backyard full of several large trees, mainly silver maples, but the lawn is very thin under there. What can we do? — Alan and Jen Sanderfoot, Middleton, Wis.
A: The conditions under your trees are pretty awful for most plants — dry shade and a soil that has had the life sucked out of it by aggressive tree roots. Just a slight change to your maple grove can help: Remove some of the lower branches from the trees and thin their crowns. This will let in more light, allowing the grass to thicken a bit, although you still won't get dense growth. After having the trees pruned, you could also replace the grass with turf-type tall fescue, a more shade- and drought-tolerant lawn grass that is well adapted to your region. Several improved dwarf varieties are available; these have the fine texture of Kentucky bluegrass and need less mowing than the earlier tall fescue selections. If foot traffic is not heavy, another option is to kill the weak turf with glyphosate, wait the proper interval for it to dissipate and then plant a ground cover through the dead grass. This will serve as a mulch to the young plants as well as a bank of decaying organic matter to enrich the soil. Sweet woodruff (Galium odoratum), perfect for light, dry shade, is a pretty semievergreen ground cover whose fine texture belies its tough, quick-spreading ways. The most radical option, however, is to remove some of the trees, making sure to keep the healthiest ones.