Why don’t evergreens change color?

Pines, spruces, firs, and hemlocks don’t change color in fall because their needles are built to last through winter. Instead of dropping every leaf each autumn, they keep their needles for several years and replace a few at a time.

Built for winter

Broadleaf trees like maples and oaks drop their leaves because a broad, thin leaf is a liability in winter. It would lose water the tree can’t replace while the ground is frozen, and it would catch snow and ice that can break branches. So they pull back what’s useful, let the leaves change color, and drop them.

Conifer needles solve the same problem a different way. They’re narrow, with a thick waxy coating and breathing pores sunk into the surface, so they lose far less water. Their cells can handle deep cold, and their shape sheds snow. Keeping needles also means an evergreen can start making food on the first mild days of spring without growing a new set of leaves, a real advantage where summers are short and soils are poor.

Evergreens do lose needles

Evergreen needles don’t last forever. Pine needles usually live two to five years, and spruces and firs often keep theirs longer. Each fall, many conifers shed their oldest needles, the ones deepest inside the branches, and those turn yellow or brown first.

Eastern white pine is the best-known example. In September and October its inner needles can turn bright yellow while the tips of the branches stay green, which often worries people with a pine in the yard. It’s normal, and the tree stays green overall.

Evergreens you’ll see on a fall drive

In New England, New York, and the North Woods, the dark green among the color is usually eastern white pine, eastern hemlock, balsam fir, and red spruce. Hemlock favors cool, shady ravines, and spruce and fir take over near the tops of the higher mountains. In the southern Appalachians, Fraser fir and red spruce cap the highest peaks, like Mount Mitchell.

Out West, the evergreens are Douglas fir, ponderosa pine, and lodgepole pine, with Engelmann spruce and subalpine fir higher up in the Rockies. A few broadleaf plants stay green too, including rhododendron, mountain laurel, and American holly in the eastern forest understory.

The conifers that do turn

A few conifers behave like hardwoods. Tamarack and western larch turn gold in fall and drop all their needles, then grow new ones in spring. Bald cypress, in southern swamps and along rivers, turns rusty orange before it goes bare, and dawn redwood, a planted tree in parks and yards, does the same.

Why evergreens make the color look better

Dark green conifers are the backdrop that makes fall color stand out. In mixed forests, scarlet red maples and orange sugar maples look brighter next to pine and hemlock. In the mountains of New Hampshire and the Adirondacks, the highest slopes are mostly spruce and fir, so hillsides stay dark green above a certain height even at peak. In the Rockies, groves of golden quaking aspen glow against dark spruce and fir.

Some evergreens change color in winter

A few evergreens take on a different color in the cold. Arborvitae, eastern red cedar, and some junipers turn bronze or purplish in winter and green up again in spring. It’s a normal response to cold and bright winter sun.