Leaves on trees expected in late April

Spring is officially here but the leaves aren’t yet on the trees.

That could soon change, but Cameron Pierce, an arborist and district manager for The Davey Tree Expert Company in Hamden said that there is no set date for trees to leaf or bloom. Each tree species and cultivar cues to slightly different ranges of temperature and daylight duration. The first trees to wake up are usually dogwoods and cherry trees.

Other flowering fruit trees, like pears, apples and plums will flower a little bit after the cherries have blossomed. Later in the spring, birches, willows and maples will flower and leaf but their flowers are much less showy, said Pierce.

Trees can tell the difference between the lengths of night and day through special, light sensitive chemicals called “phytochromes” (literally plant colors). According to an article from Penn State Extension, a sciencebased site from the university, these chemicals help the tree compare the amount of visible red light to infrared light. When there’s more visible red light, that means the day is long enough to start waking up.

Most trees will leaf out between late April and early May. Some trees will awaken early, lured into bloom by unseasonably warm weather. The lengthening days trigger the wake-up process, but a hot day can set the tree over the edge.

“Sometimes you get trees, especially flowering trees and shrubs, that get confused and they push their buds out too soon,” said Pierce. “You can lose blossoms that way.”

Before a tree produces leaves, you can tell which branches are still alive by looking at the very tips of the branches. If you see swollen, colorful buds at the end of your branches, the tree is still alive and will come back this spring. Dry, thin, black or shriveled buds are a sign that the branch has died.

“If it has any color in it whatsoever, it’s alive,” said Pierce. “But if it’s brown, black or shriveled looking than the bud is probably dead.”

Pierce said that while there isn’t a bad time to remove dead wood, now is a good time to remove it. If you want to prune a living part of the tree, it’s best to do so before the leaves first emerge. Never remove more than a third of the live wood of a tree, he said.

“Sometimes it’s best not to do a whole lot of pruning when the trees are actively using all their energy,” said Pierce. “When they’re in the middle of growing sometimes they can be a bit more sensitive.”

He said that now was the time to mulch any trees too. Mulch should be 1-2 inches thick and 2-3 times the diameter of the tree trunk to help insulate and protect the root crown during the temperature swings of the spring season.