Q: I have thousands of naturally growing mahonia bushes in front of my house in the woods. If you'd like I will donate them to you to dig all you want. Shipp Cain, Canton

A: Thank you, but I have plenty for now. These evergreen, bird-feeding, burglar-repelling shrubs can easily become more than you can handle. They spread rampantly if not removed. If you want to control them, I know of two methods that work and one that doesn't. The one that doesn't work is pruning them to the ground. They will inevitably sprout back again. Digging each one out of the ground works very well but it is a lot of labor. If you decide to spray, glyphosate plus triclopyr (Roundup Poison Ivy Plus) will kill them deader than a hammer.

Q: In floral arrangements I often see a cut flower that looks like a clump of moss on a long stem. Do you have any idea what it could be? Patsy VanHoy, email

A: Cool looking isn't it!? I have no doubt you are seeing 'Green Ball' or 'Green Trick' dianthus. The Latin name, Dianthus barbatus, tells us that it is close kin to carnations, Sweet William, and garden pinks. Most dianthus are biennial plants. You plant the seed in late spring, a green rosette of leaves appears in summer and flowers emerge the following spring. Dianthus plants you buy at a nursery were propagated in a greenhouse the previous year, so they are ready to flower after you plant them.

Q: What is the difference between annual bluegrass and rough bluegrass? Vivian Kral, email

A: Annual bluegrass, Poa annua, is a very common grassy weed in local lawns. It is a lighter green than fescue and really stands out against the brown of dormant bermuda grass. Clumps are usually covered with hundreds of white/silver seed heads. Rough bluegrass, Poa trivialis, is a perennial weed. Both grasses fade away in May, leaving dead spots in your lawn, but rough bluegrass returns in September. Annual bluegrass can be controlled with pre-emergent herbicide applied in September but controlling rough bluegrass is limited to two methods: dig up the clump or spray it with glyphosate (Roundup, etc). Replanting with your desired grass is necessary with whichever control you choose.

Q: I have some unused diatomaceous earth that I had for my pool but no longer need. Does it have any useful purpose for either the garden, lawn or flower bed? Graham Edmunds, Snellville

A: Diatomaceous earth used for a pool filter is not the same as diatomaceous earth used for an insecticide. The pool filter product has been treated to remove the sharp edges of each particle. This defeats the purpose of cutting the skin of pest insects. I don't know of an alternative use for the product other than giving it to another pool owner or putting it in the garbage.