Pruning season is right around the corner

Prune fruit trees and grapes soon as the worst of the winter cold is past and spring growth has not yet begun.

Raspberries can grow into a tangled mess and produce poorly if not pruned properly. Prune fall-fruiting raspberries (that fruit between August and October) back to the ground now to produce one crop of fruit.

Most autumn-fruiting varieties are primocanes that produce fruit in their first year of growth. Cut the old canes as close to the ground as possible so that buds will break from below the surface of the soil. New canes will grow and set fruit later in the year.

If the canes are not cut low enough, fruiting laterals may form on any remaining cane portion. These fruiting laterals will not be as healthy.

Summer-fruiting varieties are usually floricanes, which fruit in the second year of growth and thus require different pruning techniques.

• It is OK to start cutting back perennials when conditions in your garden beds are dry enough. You can damage the soil in the beds if you are walking around in them when the soil is too wet.

Do your best to avoid walking on bulbs that are emerging in the beds as the early warm weather has gotten some of them sprouting. Winter aconite and snowdrops are now in bloom at the Chicago Botanic Garden.

• March is a good month to control insects such as magnolia scale with an application of dormant oil. Verify that you have a problem insect before pursuing any controls and avoid applying unnecessary treatments.

Temperatures should be at least 40 degrees Fahrenheit with no chance of freezing or rain within the following 24 hours. Avoid spraying on windy days to prevent any drift of the spray. As with any product, be sure to read the label to make sure the plants you are treating will not be damaged by the dormant oil spray.

Dormant oils can be very effective with minimal impact on the environment when used properly.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.