Fruit trees benefit from late winter pruning

A good time to prune fruit trees is late February or early March, before the buds begin to swell.

A tree's branching habits are easy to see, and the weather is generally more conducive to outdoor work at winter's end.

A general goal of pruning a fruit tree is to thin the canopy of the tree in order to increase sunlight and improve air circulation, which in turn will increase fruit production and help reduce diseases.

Disinfect your tools with Lysol disinfectant or a solution of nine parts water to one part bleach after completing each tree and after each pruning cut if there are diseased branches present.

First remove all dead or diseased branches. These will be easy to spot because the wood is generally darker than healthy wood. Then thin the canopy by first focusing on pruning out branches that grow toward the center of the tree rather than out away from the center.

When possible, prune out branches that have narrow, V-shaped crotch angles, as they are more susceptible to breaking under pressure than a wider, U-shaped crotch angle. The angle formed by a V-shaped crotch is less than 30 degrees.

Prune out all suckers that arise from the ground next to the main trunk or grow vertically from lateral branches. Try to encourage the growth of lateral fruit-producing branches and discourage upright vertical growth that produces little fruit.

Finally, prune out branches that rub against each other or are growing over a walkway, driveway or doorway.

Avoid working in the rain or walking over the root zone of a tree when the soil is soft and wet.

• Birds are very active around the bird feeder in my garden. Consider adding a source of water for the birds too.

Adding a heater to a bird bath is easy to do. Purchase one with an automatic shut-off valve or heat cycling on-off switch, which will prevent damage to the birdbath if it dries out.

Use a grounded, three-pronged outlet to prevent the possibility of electrocution. Avoid heaters that have an uncovered heating element, as this could burn the birds' feet if they land on it.

Placing a flat piece of shale or brick over the heating element (even a covered one) will provide a warm rock for birds to perch on to rest or drink and will prevent any accidental injury, as well as keeping the heater anchored in the bird bath.

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