Evergreen trees go through a natural cycle of dropping and replacing old foliage just as deciduous plants do. They just do it on a slightly different schedule.
“Evergreens have a natural shedding cycle where they will lose their needles. For pine trees, it's every two years,” says Homegrown NH host Emma Erler, lead horticulturalist at Squam Lakes Natural Science Center.
While a maple tree will only keep its leaves for a single growing season, a pine tree may hold onto its needles for two seasons. Eventually needles become old and worn and drop from the tree naturally.
Pines, hemlocks, spruce, and arborvitae shed some needles in the fall every year and produce new needles the following spring.
The oldest needles are those closest to the trunk along a branch, so normal shedding looks like needles dropping near the inside of the tree, after turning yellow or brown in the fall.
What does abnormal shedding look like?
If the plant is shedding needles in the spring or summer, or while the inner needles are still green, it’s time to investigate if there is something else going on.
“Drought can also be an issue for evergreens,” says Erler. Shedding can be a stress response to an earlier drought, but it can also be a sign of a disease, typically a fungal disease. It could also be a result of insects, or herbicide exposure.
Once an evergreen branch has turned brown, there is little to no chance for recovery.
Most evergreen trees, like pines, hemlocks, and spruce, only produce new growth at the tips of their branches. Once these growing points are damaged or killed, the branch will continue to deteriorate. Dead branches can be pruned out at any time.
A few evergreen species, such as arborvitae and chamaecyparis, can produce new growth from latent buds along their stems as long as you don’t prune into the “dead zone” (the area beyond where green needles are growing).
How do you keep evergreens healthy?
The most important thing to do is to provide evergreens with lots of water heading into the colder months.
“If the weather gets really dry in late summer and into the fall, even up until the ground freezes, it's important to continue watering so that that plant is in the best possible health going into the winter months,” says Erler.
This is especially critical with plants that are at the mercy of windy conditions in winter, or at the edge of a road or yard where they could be exposed to road salt or spray.
Wrapping evergreens in burlap can prevent damage from drying winter winds, and damage from deer.
See you in the garden!
If you have a gardening question for Homegrown NH, email or send a voice memo to HomegrownNH@NHPR.org.
Homegrown New Hampshire is a collaboration between Squam Lakes Natural Science Center and NHPR.
