Our warming temperatures are a tease. (And they are warming, despite last weekend’s chill.) The ground is not ready to be worked because it is snow-covered, frozen or soggy – depending on the weather that day or your location in Maine. But it is warm enough to do some outdoor chores comfortably.

That means it is time to prune.

Late winter – remember that spring does not start officially until March 20 – is the recommended time for pruning many trees and shrubs.

Pruning now has several advantages. First, with the leaves off the trees the branching is more visible on deciduous trees so you can more easily see what needs to be removed. Second, winter pruning stimulates growth, so the plants will get a good start once the warm weather arrives.

Some trees and shrubs should not be pruned in spring. I’ll start with those in case you are so eager to prune that you head outside before finishing this column: Avoid pruning trees and shrubs that flower early in the spring, such as forsythia, lilacs, azaleas, rhododendrons, quince, mountain laurel and ornamental fruit trees. These early bloomers produce their flower buds late the previous season, so if you prune now you will be cutting out future flowers. If you don’t mind losing your blooms this spring, go ahead and prune them. Otherwise, wait until right after their blossoms go by.

Second, avoid pruning trees in which sap flows heavily in the spring, including maples, birches and walnuts. While pruning now won’t hurt the tree much, it does get messy as the sap runs from the cuts.

With hydrangeas, when to prune depends on the type you have. Paniculata, oak-leaf and arborescens hydrangeas bloom on new wood, so they can be pruned now. Macrophylla or big-leaf hydrangeas bloom on old wood, so they should be pruned after they bloom. The Endless Summer hydrangea series blooms on old and new wood, and are best pruned after they bloom.

But after you exclude spring bloomers and sap runners, there are still a lot plants that can be pruned, including dogwoods, clethra, rose of sharon, butterfly bush, spirea, oaks, euonymus and most needled evergreens.

You prune for several reasons. When you face each bush or tree, your first step is to remove dead and diseased branches. You can tell dead branches in winter because the bark is worn off or they are broken or unhealthy looking. With viburnums, check the tips of twigs for eggs of the viburnum leaf beetle and trim those twigs out with your hand pruners.

The next step is to remove branches that are rubbing against each other or crossing, any branches that are touching the ground or are weak or spindly.

Once all of that is done, your job may be done, too. Or you may want to start controlling the size and shape of the plant. Remove branches growing where you don’t want them: in a walkway, blocking a window, in the way of mowing or near power lines.

This is a judgment call, but you should remove branches growing in the wrong direction. Anything going straight up to the sky or sticking out beyond the center mass of the plant usually should go. Also, if one branch sticks out farther than all the others, cut that one back with your hand pruners. This is sort of like getting your hair trimmed: when you’re done, all the hairs aren’t the same length but together they make an attractive unit.

Pruning has some simple rules. First, don’t just cut the top off trees, an approach called tree topping. Cass Turnbull, whom I have written about several times and who unfortunately died in January at the age of 65, led a campaign against topping, correctly pointing out that it creates ugly, unhealthy trees and shrubs.

Unless you are dealing with a boxwood or similar plant you should not use hedge trimmers to shear a plant. And, for goodness sake, don’t use your gas-powered lawn trimmer, which I have seen people do. That is just nasty. And messy. Anyway, any kind of shearing creates an unnatural look and an unhealthy, twiggy growth at the tips of branches.

With fruit trees, you want to open up the middle of the tree so that sun reaches all of the branches. You should cut branches as close to the bottom of the tree as practical. For some shrubs, that means cutting the largest branches right at ground level. To figure out where to make the cut, always go back to another branch.

With evergreens, reach into the center of the plant so that any cuts you make are invisible. But other than removing damaged branches or pruning to keep the patient from getting too big for its spot, evergreens require little maintenance pruning.

Pruning is as much art as science. Cartoons often show artists standing back, holding up their thumbs to get the perspective of their paintings. Stand back, look at the plant from different directions and remove anything that seems out of place. When you’re done pruning and have a pie of branches and twigs, if you have space, leave the pile in the woods on your land so they will provide shelter for wildlife and eventually decompose.

In pruning, trust your instincts. You are not merely a gardener. You are an artist whose medium is plants. Don’t worry – it is difficult to prune a tree or a shrub to death.

Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at 767-2297 or at: [email protected]