QUESTION: Can you give me advice on eradicating mugwort from my flower beds? We weeded it out last summer only to have it return with a vengeance this season.ANSWER: Best advice is not to yearn for perfection. Mugwort (Artemisia vulgaris) is called chrysanthemum weed, because it looks somewhat like a rangy mum without flowers. It has a vigorous root and rhizome structure, meaning you can't just pull it - each above-ground bit of the plant is attached underground to others. And, to make things worse, it can regenerate from broken pieces of root as small as one-quarter inch in length, according to the Journal of Environmental Horticulture. (Therefore, never rototill a mugwort patch; you would just exacerbate the situation.)Here's what Penn State's online Hortweb has to say: "The only way to eliminate mugwort from many plantings is to kill everything in the area and start over." Gulp.More bad news. Roundup, the herbicide with less residue, is reported to have only so-so effect. One herbicide for which success has been reported is so toxic that you have to wait two years to replant the area.So, weed what you can. I suspect that repeated applications of Roundup would help - be sure to get the undersides of the leaves (as always, do this on a day with no breeze and keep the herbicide from touching desirable plants). And don't give away plants from infested beds without full disclosure.

QUESTION: I recently placed garden soil in my flower bed because the bed looked as if it had sunk a little. Then I put mulch over the top to help with weeds. I'm having second thoughts. I have many perennials and don't know where everything is. Could I be causing my flowers not to bloom?ANSWER: You may have gone overboard. Most perennials grow at a particular level in relation to the soil surface, many with the crown (the juncture of roots and above-ground growth) even with the surface. Others grow from rhizomes or tubers that should be close to the surface (such as bearded iris) or a certain depth below (such as peonies, two inches deep). If you raise the surface of the bed without adjusting the plants, they will be unhappy (peonies won't bloom if too deep) or smothered.Mulch is best applied as perennials are beginning new growth. Do not cover them; loosely surround the crown with mulch. (Too much mulch close to the crown invites decay and insect damage.) Do not overmulch; a two-inch layer is the maximum, and an inch is usually adequate.Many people think the main purpose of mulch is to get rid of weeds with a one-dump approach. Weed suppression (not elimination) is indeed one of the functions of mulch, but the main reason to apply mulch is to conserve moisture and moderate the effects of the sun heating the surface. Organic mulches also break down over a year or two and add humus to the soil.Send your gardening questions to Michael Martin Mills, The Philadelphia Inquirer, Box 8263, Philadelphia, Pa. 19101, or send e-mail to Millsm@phillynews.com