Q: A large linden grows in an opening in the paving in front of my house. It’s a beautiful, healthy tree, and I want to care for it well. How should I fertilize it? — William Morrow, Washington, D.C.
A: If your linden is thriving despite the rough conditions it has to endure, I suggest you continue the “fertilizer regime” of benign neglect. Fertilizer can easily burn roots, especially when concentrated in a small area like a sidewalk opening. Putting a 1-inch layer of organic mulch such as fine bark chips over the opening will protect the tree from the insults of human and canine traffic. If you must give the tree something, the best you can provide is water, applied generously during extended periods of drought and heat.