Plant of the week: annual vinca

Low maintenance, good drought tolerance, and easy availability all help popularize annual vinca. (Courtesy of Ginny Williams, Handout photo / August 10, 2011)

My mugo pine has white things on the needles like paint flakes. Do I need to address this?

That is pine needle scale, a native pest that also occurs on other pines and spruce. Scale insects hide under their shell-like cover and suck out cell contents. Normally, native insects such as lady beetles and parasitic wasps keep this scale under control, but if you see a lot of white flecks, a plant could suffer yellowing, stunting or dieback. Apply a summer-weight horticultural oil twice, in mid-May and late July, when the eggs hatch over two to three weeks and little red crawlers are visible (you may need a magnifying glass to see them). At this time, the crawlers have no protective cover and are vulnerable. Dormant oil can be applied during the dormant season.

I hear the University of Maryland is having a vegetable gardening contest. Is that only for master gardeners?

Not at all! This is the inaugural year for the Grow 100 Challenge, which asks, "What can YOU grow in 100 square feet?" Sponsored by Grow It Eat It, University of Maryland Extension's food gardening network, this contest is open to all Marylanders and beyond. It features three categories: new to gardening, four R's garden (reduce, reuse, recycle, rethink), and maximum production. The 100 square feet of garden space can be in many configurations: part of a larger garden, several smaller plots, salad boxes, etc. Find out more here. Deadline is June 15.

University of Maryland Extension's Home and Garden Information Center offers free gardening and pest information. Call 800-342-2507 or send a question to its website at extension.umd.edu/hgic.

Plant of the week

Annual vinca, Madagascar periwinkle

Catharanthus roseus

Low maintenance, good drought tolerance, and easy availability all help popularize annual vinca (not to be confused with vinca major or minor, the evergreen ground covers.) A Madagascar native, annual vinca grows 11/2 feet tall and wide, blooming continuously in pink, purple, salmon, white or red from June until frost. Annual vinca is unlikely to be eaten by deer when other plants are available. In spring, plant in any well-drained, though not cool, soil. It must have a sunny site for good bloom. For best results, keep soil evenly moist, not soggy. Use in hanging baskets and borders, or as a ground cover or houseplant.

— Ginny Williams