Bulbs may begin showing spring's arrival
During periods of warm weather, early bulbs might begin sprouting, especially those planted with a southern exposure, close to a house or garage.
The Chicago Botanic Garden has on occasion had snowdrops in flower in late February in similar locations. The first greenery to show is foliage, with flower buds appearing much later in the bulb's growth. Subsequent cold weather might damage the edges of the foliage, but unless the flower bud has appeared, it will not affect the future flowering or health of the bulb.
A few of the small early bulbs can tolerate a bit of frost. They include winter aconite, snowdrops and glory-of-the-snow.
• You may be seeing winter burn on broad leaved evergreens such as boxwood, rhododendron and holly, and needled evergreens such as yew and arborvitae. Winter burn is a cultural condition that affects plants that do not lose their leaves over the winter. Leaves turn yellow and then brown in response to specific weather conditions.
Leaves do not actually burn but rather dry up. Salt spray from vehicle traffic can also damage foliage. Symptoms of winter burn typically appear first in late winter and accelerate in early spring. Various conditions combine to cause leaves to dry out.
Mild winter temperatures and warm winter sun prompt leaves to process water, which cannot be replaced if the ground is either frozen or very dry. Winter winds also contribute to the problem. Winter burn is common after extremely cold and extremely mild winters, and in both cases it is exacerbated by lack of snow or rain in combination with strong winds and abundant sun.
It is best to wait until new growth appears in many situations before pruning out damaged areas if you are not sure whether sections are completely dead. I have seen boxwood with an overall brownish cast in very early spring that completely greened up later in the season.
In general it is a good idea to plant broad-leaved evergreens where they will have some protection from winter sun and wind.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.