Q. A tall weed with clusters of small white flowers has taken over the edge of our woodland garden. When the leaves are crushed, it smells like garlic. Do you know what the weed is and how to control it?

A. This is garlic-mustard weed (Alliaria petiolata), a very prolific seeder that can be difficult to control, once it is established. The good news is that it is very easy to hand pull; however, you must pull it early in the growing season before it has an opportunity to reseed itself. Therefore it is important to know what garlic-mustard weed looks like when it is young. When you see the young seedlings, they should be pulled immediately. This weed has taken over large areas of our native woodland and is choking out native plant species. It grows in very diverse climates throughout the Northeastern and Midwestern states and has spread into states in the Southeast and Northwest.

Q. I would like to plant some bee balm in our yard. Can you give me some tips on what variety to select and how to best grow it?

A. Bee balm (Monarda didyma) is a native plant that is very easy to grow in most situations. It will grow in full sun or partial shade, and prefers well-drained soil that has been supplemented with organic matter. It thrives in a moist spot, but will survive drought conditions. The biggest problem with our native bee balm is that it is subject to powdery mildew disease. To avoid this problem, you should plant the native species in a sunny location with good air circulation. You might also consider purchasing one of the disease-resistant cultivars now available. Like other members of the mint family, bee balm spreads rapidly into dense clumps and tends to crowd itself out. It must be divided every two to three years.

Q. My annual flowers got off to a very slow start, so I am going to fertilize them. How often should I fertilize my flowers?

A. Your flowers may need fertilizing, but cool spring weather also limits the growth of annuals early in the season. I recommend using compost to enrich your soil and if supplemental fertilizer is needed I would suggest that you use a slow-release organic fertilizer.

Typically, these types of fertilizer only need to be applied once or twice in the growing season. They should be incorporated into the soil at planting time, and if necessary a second application can be spread around the plants in mid to late summer. This will carry them through the fall. Most chemical fertilizers release nutrients more quickly, but they need to be applied more often. Please read the fertilizer label for specific instructions.

Dennis Bishop is an urban horticulture educator for the Baltimore office of the Maryland Cooperative Extension Services. If you have a gardening or pest problem, you can call the Home and Garden Information Center hot line (Monday through Friday, 8 a.m. to 1 p.m.) at 800-342-2507. You can also e-mail questions, order publications and diagnose plant problems by visiting the Web site, www.hgic.umd.edu.

Checklist

1. Many lawn diseases begin in early summer. To avoid diseases, water early in the day and do not water during the evening hours.

2. To ensure long continuous blooms from your perennial plants, keep them dead headed during the summer months.

3. Check plant twigs and branches for evidence of scale insects. Mature scales look like very tiny shells that are attached to the twigs and branches.