Why are evergreen trees turning brown?

Some browning on evergreens is perfectly normal, and some is a warning sign. Where the brown shows up, and when, usually tells you which.

A browning evergreen is alarming, but it isn’t always bad news. Every evergreen eventually sheds its older foliage, whether needles or broad leaves. Many conifers drop old needles in fall, while hollies and southern magnolias drop many of their oldest leaves in spring as new growth begins (Clemson Extension). The trick is reading the pattern: which needles turned, where on the tree, and when. This guide covers conifers such as pine, spruce, fir, arborvitae, juniper, yew, and hemlock, plus a few broadleaf evergreens such as boxwood and rhododendron.

Normal fall needle drop

Conifers don’t keep the same needles forever. Every one sheds its oldest, innermost needles after one to several years, depending on the species, usually in fall (Utah State University Extension). Pines typically hold their needles 2 to 6 years and spruces 3 to 10, and white pine keeps them only about two or three, so its fall drop is the most dramatic (Purdue University; The Morton Arboretum). Spruce and fir shed gradually, so it’s rarely noticed, while pines and arborvitae show it plainly. Arborvitae drops whole small branchlets rather than single needles, and they can hang on brown for a while (University of Wisconsin–Madison Extension).

Signs that it’s normal: the yellow or brown needles are the older ones on the inside of the tree, there’s a clear line between them and the green needles farther out, the branch tips stay green, and the change happened fairly quickly in fall (University of Wisconsin–Madison Extension). Worry instead if the current year’s growth at the tips is discolored or wilted (The Morton Arboretum).

A few conifers, including larch (tamarack), bald cypress, and dawn redwood, drop all their needles every fall. A whole tree turning gold or rust is exactly what they’re supposed to do (University of Wisconsin–Madison Extension). See why evergreens stay green for more.

Winter burn

On sunny, windy winter days, evergreen foliage keeps losing water, but frozen soil keeps the roots from replacing it. A dry fall makes it worse (West Virginia University Extension; University of Minnesota Extension). The damage often doesn’t show until late winter or early spring, when needles turn yellow or reddish brown from the tips back (Maine Department of Agriculture).

Look for it on the south, southwest, and windward sides, next to sunny walls or pavement that reflect heat, and above the snow line, since snow protects whatever it covers (University of Minnesota Extension; Washington State University Extension). Yew, arborvitae, and hemlock are among the most prone (University of Minnesota Extension), along with juniper, boxwood, rhododendron, and dwarf Alberta spruce (University of Wisconsin–Madison Extension).

Brown needles won’t turn green again, but buds are tougher than needles and often push out new growth that fills the gaps. Wait for new growth in spring before pruning (University of Minnesota Extension; Washington State University Extension). To prevent it, water evergreens deeply through the growing season and into fall until the ground freezes, spread 3 to 4 inches of mulch (kept off the trunk), and for exposed plants, set up a burlap screen on the sunny or windy side, open at the top (University of Minnesota Extension; Washington State University Extension). Anti-desiccant sprays are often sold for this, but extension research finds them unreliable (University of Wisconsin–Madison Extension).

Broadleaf evergreens react differently. Rhododendron leaves curl tightly in the cold to protect themselves and uncurl when it warms (UNH Extension). Boxwood often turns bronze or orange in winter and greens up again in spring. If the color change is even and the leaves stay on, it’s likely winter stress; random, spreading browning with leaf drop points to disease (Clemson Extension).

Drought

Conifers are slow to show drought injury, so a tree can look fine while the damage is happening (University of Missouri). Symptoms can appear a year or more after the drought, as branches die back from the top of the tree, new shoot tips droop and brown, and the crown thins (UNH Extension). Drought-weakened trees are also more open to bark beetles and root rot. When you’re trying to explain browning, think back to last summer and fall.

Road salt

Salt reaches evergreens two ways: spray kicked up by traffic, which is worst within about 60 feet of the road, and salty runoff and plowed snow that soak into the soil (University of Minnesota). Spray damage shows on the side facing the road, with browning that starts at needle tips, appears by late winter, and gets worse into spring and early summer (University of Minnesota; UMass Amherst). White pine, red pine, Norway and Colorado spruce, Douglas fir, yew, and hemlock are among the most sensitive; Austrian pine is among the most tolerant, but no species is fully salt-proof (University of Minnesota).

Diseases

Rhizosphaera needle cast is common on Colorado blue spruce. Older needles turn purple-brown in spring or early summer and drop, starting on the lower branches and moving up, while the new tips stay green. Under a hand lens, tiny black dots line up in neat rows on the needles (University of Minnesota Extension).

Cytospora canker also hits older spruces, mostly blue and Norway. Lower branches brown and die first, and patches of white to amber resin show up on the bark (University of Illinois Extension).

Diplodia tip blight attacks two- and three-needle pines such as Austrian, Scots, ponderosa, red, and mugo pine. New shoots come out stunted, with short brown needles and beads of resin (Penn State Extension). Dothistroma needle blight leaves reddish-brown bands on pine needles before they brown and drop, worst on the lower branches (Penn State Extension). On Douglas fir, Rhabdocline needle cast causes reddish-brown blotches on the needles and early needle loss, worst low in the shade (UMass Extension).

Phytophthora root rot strikes evergreens in wet, poorly drained soil, including arborvitae, yew, juniper, hemlock, white pine, and rhododendron. Plants wilt and decline, often with reddish-brown wood at the soil line (Penn State Extension).

Insects and mites

Spruce spider mites are a cool-weather pest of spruce, arborvitae, juniper, hemlock, and pine. Needles look speckled and off-color, then rusty, starting with the older, inner needles. Tap a branch over white paper; tiny moving specks are mites (Penn State Extension). Bagworms hang their spindle-shaped bags on arborvitae, juniper, and red cedar and can kill a heavily infested evergreen (Ohio State University Extension). On white pine and Norway spruce, a top shoot that wilts into a shepherd’s crook and browns by midsummer is the work of the white pine weevil (Cornell Cooperative Extension). And on hemlocks in the East, small white, cottony tufts at the base of the needles are hemlock woolly adelgid, a serious invasive pest that turns trees grayish and can kill them in 4 to 10 years (Michigan Invasive Species Program).

Other causes

Newly planted evergreens often brown from transplant shock, because their roots were damaged in the move; they can take years to settle in, so water them regularly through the first year (Montana State University Extension). Trees planted too deep, with no visible flare where the trunk meets the ground, can decline years later (Ohio Department of Natural Resources), and roots that circle and squeeze the trunk cause a slow decline (Purdue Landscape Report). For other leaf and needle problems, see what’s damaging these leaves?

Will it grow back?

It depends on the plant. Most conifers, including pine, spruce, fir, juniper, arborvitae, and hemlock, have no live buds on older, bare wood, so a branch that’s brown all the way back won’t refill. Yew is the big exception and can regrow from old wood (UMass Extension). Where buds survived, new growth can fill in over a few seasons.

To check a branch, scrape a little bark with your thumbnail. Green underneath means it’s alive; brown and dry, or twigs that snap, means it’s dead (Washington State University Extension). Wait until new growth appears in spring, then prune back to live wood. Dead branches can come out any time. If you suspect disease or pests, your extension office’s plant diagnostic lab can identify it from a sample, and a certified arborist can assess large or valuable trees (Penn State Extension).

Harmless or serious? A quick check

• Inside or outside? Old inner needles with green tips are normal. Brown on the new growth at the tips is a problem.
• Which side? One side facing the sun, wind, or a road points to winter burn or salt. Browning that starts low and climbs points to disease.
• When? A quick change in fall is usually normal drop. Browning that shows in late winter or spring suggests winter burn or salt, and browning in summer suggests something else.
• Getting worse? Normal drop repeats each year without thinning the tree. Browning that spreads to more branches year after year needs a closer look.
• Look back. Drought, construction, and planting problems can show up a year or more later.

These rules of thumb come from the extension sources above (University of Wisconsin–Madison Extension; The Morton Arboretum; Clemson Extension).