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Gardening tips: Last chance for tree pruning – but just a touch – before spring

Blazing leaves of a red Japanese maple soak up the sunlight at the Shinzen Friendship Garden at Woodward Park. The garden hosts pruning demonstrations for maintaining healthy plants.
Blazing leaves of a red Japanese maple soak up the sunlight at the Shinzen Friendship Garden at Woodward Park. The garden hosts pruning demonstrations for maintaining healthy plants. Fresno Bee file

This week is your last chance to prune deciduous plants and trees. Our winter has lasted a couple of weeks longer than usual this year, but as temperatures warm, the sap is rising. Late, hard pruning after plants have begun to exit winter dormancy thwarts the spring growth spurt and can stunt plants’ vigor. Removal of dead or diseased wood can take place any time of the year, but late pruning should be more of a light shaping.

If your unpruned roses are already showing new buds along the bare canes, prune down only about a quarter of the length of the cane instead of reducing cane length to the normal (in our warm climate) 12 to 18 inches. Cut back rose canes that rub against other canes, but leave the rest of the cane structure as it is this year. Do the same for trees and bushes. Cut dead, broken or diseased wood back to a main branch, trim out any branches that cross through the interior (to provide better air circulation), but stop your pruning at that point. You can trim off perhaps one quarter of overly long fruit and nut tree branches now, but should plan on providing branch support and doing some extra thinning later in the season to prevent branches breaking under the weight of a ripening crop.

Trees that lost their leaves latest in the fall season will be slower to come out of dormancy in spring. Japanese maples usually can be pruned in February without causing harm.

Pruning Japanese maples well is a real skill. So many of the Japanese maples in our area have been badly pruned, resulting in bushy, clumsy-looking trees that don’t display their elegant, open natural form.

There are quite a few YouTube videos on pruning Japanese maples, but I’ve not found one yet that clearly demonstrates what to look for as you prune. Not many of the most popular pruning books include instructions on proper maintenance of Japanese maples. One of the best sources we have are the beautifully maintained trees in the Shinzen garden in Woodward Park in Fresno. It’s worth taking a field trip to the gardens to study and photograph the branch structures of well-pruned Japanese maples. The garden will hosting their Spring Blossom festival soon. Check their website (www.shinzenjapanesegarden.org) for dates and times of events and for any pruning demonstrations during the year.

The most important tip in pruning Japanese maples is to never cut across a branch. A tuft of new leaves will sprout out of the cross cut, deforming the shape. Study the placement of the leafy branches along the main branches and try to make heading or size-reducing cuts where a strong leafy branch is growing in the desired direction. The second important tip is to make sure that the leaf canopy shades the bark. So many of our Japanese maples receive too much direct sunlight that can burn the bark and stress or kill the tree.

Reshaping a deformed Japanese maple can take years of good pruning, since only one-third of the canopy’s branch structure should be removed each year. Go slow with your pruning. Do just a little every spring to get the hang of it.

Japanese maples have four growth surges (called flushes) during the growing season. In September, the trees often produce long whips that should be cut back to a main branch or the trunk.

Send Elinor Teague plant questions at etgrow@comcast.net or features@fresnobee.com (“plants” in the subject line).