Q: I would like to make a raised bed to plant perennials and annual flowers. The area has a lot of tree roots. My husband suggested using Roundup to kill the grass in the area before adding soil.
A: You’ll be taking a gamble by spraying glyphosate (Roundup) weedkiller on the roots of a tree. Typically roots don’t absorb much of the chemical but I’d hate for your tree to be hurt. It would be safest to just pull the weeds by hand. You could also choose to wipe herbicide onto the grass using a foam paintbrush. The soil in the new bed needs to be at least six inches deep. If you use one of the bagged garden soil (not topsoil) products, that depth of material should not hurt the tree roots.