Everyone knows that autumn is the time for trees to turn colors and lose their leaves. Thousands of families pack their cars and drive out to the country to see colorful hardwood foliage as trees prepare for winter.
But, what about the pines? After all, they are evergreens and evergreens are always green, right? Not exactly. Leaves of pines (we call them needles) turn colors and drop in the fall.
For most of the year, when a pine turns yellow, it’s a sign that something is wrong with the tree. In the fall, it’s a different story. Concerned their trees are dying, homeowners and forest landowners with yellowing pines often call foresters and tree care experts this time of year. When told it is just fall color, tree experts often hear a common skeptical reply, “But pines are evergreen—they don’t turn colors.”
Both the experts and the concerned callers are correct. To understand this, consider that needles on pine trees in North Carolina usually live for two growing seasons. During the second growing season, needles become shaded and require more maintenance as they age. So, like deciduous hardwood trees, pines will quit maintaining these older, less efficient needles and cut them loose.
When looking at pines this fall, you will see that most have both yellow and green needles. A closer look will reveal that the yellow needles, last year’s needles, are closer to the trunk. The green ones, this year’s needles, are closer to the branch tips.
After a windy day or a wind event, you may find a blanket of yellow needles covering the ground beneath your pines and a fresh blanket of green needles covering branches with color and smell, reminding you that it’s almost time to buy a North Carolina Christmas tree.
Don’t worry about your pines running out of needles. While only one flush of leaves will be present in the winter, a new flush will emerge next spring so there will always be two flushes of needles going into the growing season.
Now, if you see a tree with all its needles turning yellow this time of year, it is either trying to impress its hardwood neighbors or it is time to call a pine doctor who makes house calls.