Q: I planted dozens of redosier dogwoods on an embankment by my house ten years ago. For the first two years, they produced beautiful red twigs. Since then, the number of red twigs dwindles. Is there anything that I can do to increase the production of red twigs? Is something wrong with the soil? – P.W., Madison

A: Cut the stems back to the ground. Like most shrubby dogwoods, the redosier dogwood responds to severe pruning with vigorous growth. Most likely, there is nothing wrong with your soil. The condition you’re witnessing is simply caused by the nature of maturation of this particular dogwood.

Interestingly, in its native habitat, the redosier dogwood is a food source for beavers. The plant responds to severe pruning by sending out a vigorous new flush of growth after it’s been heavily munched upon. In the landscape, if the plant is not pruned back every three or four years, the twiggy shrub tends to develop gray bark that is not nearly as striking as the bark on younger twigs. So, mimic beaver foraging – cut the stems to the ground, and you’ll likely observe a return of deep red stems.

Q: Are azaleas one of the plants you should prune in winter? – P.T., Thomaston

A: No, they aren’t. One should prune azaleas just after they have finished flowering in early summer. Flower buds for 2006 will set by midsummer this year, and any pruning after mid-June could result in diminished flower production for next year.

When pruning, use hand pruners; do not shear the branches. Shearing will result in a wildly branching structure that will be both unbecoming and unhealthy for the shrub. The priority when pruning should be to remove all dead or damaged wood first. Decayed branches should be pruned back to clean white wood.

Next, prune away any branches that crowd the inner canopy of the shrub. Remove individual branches back to the spot where they join a larger branch – don’t leave “stubs” that make healing the wound site difficult for the plant; they’ll invite fungal rot and decay.

Old azaleas that have grown too large for their space in your garden can be brought down in size by cutting the large branches back severely. New growth will spring from the stems that are left.

Q: Can you tell me about the Ginkgo biloba tree? – T.W., Northeast Harbor

A: Ginkgo is a deciduous tree, bearing unique simple, fan-shaped leaves and greenish flowers in spring. In autumn, the tree produces stunning fall color. It is native to eastern China and was introduced to our continent in the late 1700s.

When young, the ginkgo has a very pretty pyramidal growth habit and a tidy canopy outline. As it matures, however, the tree can become quite majestic looking, developing massive branches and a grand, spreading canopy. Each ginkgo seed will produce either a male or female tree. One of the drawbacks of growing the tree is the production of messy, foul-smelling fruits by the female plants. Occasionally, handling these fruits can cause the gardener to develop a poison ivylike rash.

It may take 20 to 50 years for a ginkgo tree to flower from seed. Thus, determining the gender of the plant can take decades. For this reason, it is recommended to plant male trees, grown as clones.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, 512 North Ridge Road, Montville 04941 or e-mail dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.