Q: I have a butterfly bush that is overgrown. When is it safe to prune it back and how far?— Beth Burnett, email

A: You can cut back the butterfly bush anytime after the first killing frost. It will undoubtedly still have leaves on it, but you can remove everything above 18 inches from the ground. This will stimulate the plant to put out vigorous new growth in April, and fragrant blooms will appear for the rest of the summer.

Q: My wife and son suggested we use decorative rocks in our flower beds instead of mulch. I had always heard that we should not use decorative rocks. What do you think?— Mark Schmetzer, Conyers

A: Stones are good for decor but not for mulch under plants. My biggest objection to stones is practical. If leaves and straw fall on the rocks, they are the very devil to keep clean! You’ll have to blow or sweep the site almost daily. In addition, if you change your mind in a few years, the rocks are almost impossible to remove. They seem to burrow into the earth and cement themselves in place. This latter concern might be avoided by covering the soil with landscape fabric before applying the rocks. My biggest objection, though, is that rock mulch doesn’t feed the soil like straw or wood chips would. Try the rocks if you like, but keep my concerns in mind.

Q: This summer a neighbor and I planted tomatoes and peppers in a very sunny spot. The plants did well, but due to our inattention, the plot became overwhelmed with weeds. Is there any way to eliminate weed seeds before next spring?— Dave Kummer, email

A: Unlike a financial institution from which you can withdraw your deposits at any time, a “seed bank” is not so flexible. Most weed seeds are well-equipped to survive winter cold. There are no fumigants to usher them out of existence. You could consider “solarizing” the plot by stretching clear plastic over it, but that only works during summer, not winter or spring. The best you can do is to fight them on all fronts as the weeds emerge next spring. For spot spraying, I use herbicidal soap (Bayer Natria Grass & Weed Killer) or plant oils such as citrus oil (Nature’s Avenger) or clove oil (BurnOut).

Q: Do squirrels return to the nest they have built year after year? Do “new” squirrels ever move in to take over the nest? Should we remove the nests?— Fran Sommerville, Marietta

A: Yes, gray squirrels do reuse their nests. But wild squirrels are not likely to live more than a couple of years, so new families move into unoccupied nests regularly. If a nest is lost during a storm, squirrels are quick to find another spot to build a new home. Removing the nest won’t do much good to control their numbers. Squirrel populations rise and fall naturally. There is little a homeowner can do to affect their numbers.

Q: Have you ever tried grinding straw for mulch? This year I dragged my ancient leaf chopper out of the basement and ran two bales of straw through it. I got the most beautiful golden mulch. It really creates a whole new look in the flower beds.— Candace Langford, Athens

A: I’m sure your mulch is beautiful, but I use wheat straw in my garden for a different reason: It attracts beneficial spiders. Arachnophobes might recoil at my suggestion, but when they see the diminished number of sucking insects, their convictions might change. I rarely see spiders during the day unless I go looking for them. My guess is that they hide during the day but go hunting for aphids at night. I use less insecticide as a result.