Wild onions are the worst weed in my flower beds. Would it be safe to use an herbicide that only kills grass?

Wild onions and garlic are not grasses but bulbs, and cannot be controlled with a grass-selective herbicide. A broad-leaved herbicide should be used, though apply it very carefully to avoid injuring desirable plants. The waxy coating of onion and garlic leaves repels liquids. To increase herbicide absorption, crush the foliage before applying. Multiple applications will probably be needed. It is often easiest to hand dig the clusters of bulbs and take them all out in one effort. Garlic and onion bulbs multiply underground, but their flowers also produce bulblets that fall to the ground. Don’t let the flowers mature. For details, search wild onion or garlic on the HGIC website below.

I’m battling scale infestation on Kentia palms that I’ve had over 15 years with little success. I apply Bonide twice a month and soap once or twice a month. This is very time consuming. Should I use other chemicals? Should I apply more frequently? (The manufacturer was not helpful when I called.) Any other suggestions?

Houseplant scales are notoriously difficult to eradicate. With indoor climates, there are many more generations of scale a year, and they can overlap. This is the heart of the difficulty in controlling indoor scale. Horticultural soap will only be effective on the crawler stage, which has no protective cover. Scout carefully for crawlers and apply then. Your best bet is a systemic pesticide formulated for houseplants with the ingredient imidicloprid. Follow label instructions regarding application intervals. Over-application will not increase effectiveness. An alternate approach is to place your plants outside over the summer, giving beneficial parasites of scale a chance to attack them. In truth, sometimes the best course of action is to discard scale-infested plants and buy new, clean ones.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.