Winter burn and frost injury to leaves and shoots: what extension services describe

This page describes what the named extension services say. It does not diagnose a tree, say whether any tree is safe or unsafe, or tell anyone what to do about an injury. The Missouri Botanical Garden lists both under environmental problems.

Two different injuries

Injury	What the sources say causes it	What the sources say it looks like
Winter burn (desiccation)	Evergreens keep losing water through leaves and needles in winter while frozen soil blocks the roots from refilling them. Sun, wind and temperature swings drive the loss (Penn State, New Hampshire). The Missouri Botanical Garden names low soil moisture, freezing temperatures and blowing wind.	Browning at leaf margins, tips and tops; yellow to red needle tips on fir, spruce and pine; worse on the side facing sun and wind (Penn State, Missouri Botanical Garden).
Frost injury	Below-freezing temperatures freeze water inside cells, and the ice crystals rupture the cell walls. Late spring and early autumn frosts do the most harm to tissue that has not hardened off (Missouri Botanical Garden).	New leaves and tender shoots are hit first, then plants turn limp, blackened or distorted. Evergreen shoot tips curl downward and turn red or brown one to two weeks later (Missouri Botanical Garden).

Which plants the sources name

Penn State Extension (article updated November 10, 2025) says winter burn affects evergreen and semi-evergreen plants because they keep transpiring through winter. It lists azalea, boxwood, rhododendron, mountain laurel and holly among broadleaf evergreens, fir, spruce, pine, yew and hemlock among needled evergreens, and arborvitae, juniper and false cypress among scale-leaved ones. It says damage is worst on tissue farthest from the veins, such as leaf edges and tips and the tops of plants, and that whole branches or whole plants can die.

The University of New Hampshire (Extension, May 24, 2019) reported that no species was spared that spring. Rhododendrons showed symptoms first, in early March, with bleached and rolled leaves, marginal browning, flower bud desiccation and shoot dieback. Inkberry holly followed, then junipers, yews and false cypress with tip burn, scorch or whole-branch dieback. It said the winter was mild by human standards but had a swing of as much as 60 degrees in late February, little snow cover, many sunny days and wind.

What else the sources say adds to the damage

New Hampshire says shrubs sheared in fall, or plants whose neighbours had been cleared or trimmed, were more exposed and may have dried out more. It adds that salt spray from treated roads regularly dries out nearby pines and other trees, which usually grow out of it. Penn State says a plant that is hardy for its zone is no guarantee against winter burn when storms and swings are harsher. New Hampshire also reports that cold snaps after growth began may have killed buds or patches of cambium, with cherry and plum dieback reported, and that shallow-rooted plants such as blueberry could be hurt when soil ran colder than normal for lack of snow.

Frost on fruit trees

The University of Missouri (Michele Warmund, April 22, 2021) says the amount of fruit lost to a spring frost depends on the stage of bud development, the low temperature reached, how long it lasted and the weather in the days before. Its example is apple: buds at silver tip usually tolerate temperatures as low as 15°F, while flowers at full bloom may avoid injury only at 28°F or above. It describes cutting twigs with flowers and keeping them in water indoors, where frost-injured petals and pistils turn brown within two days. It also reports a brown frost ring on young apples and pears that is still edible.

What the sources say follows the injury

Missouri says peach, nectarine, apricot, plum and cherry are often susceptible to Leucostoma (Cytospora) canker after cold injury, and that some insects and diseases favour weakened tissue. New Hampshire says other pathogens may colonize stressed tissue and that vole damage or stem girdling at the base of dead branches is worth separating from winter burn. New Hampshire and the Missouri Botanical Garden give different timings for judging damage: New Hampshire says to wait until new growth shows the extent, and the Missouri Botanical Garden says to wait until after the final frost date of spring before pruning dead areas.

What the sources list for prevention

Penn State lists plant choice and placement out of the wind, mulch, burlap screens for newly planted evergreens, avoiding late-summer pruning and fall fertilizing, and deep watering in fall dry spells. Missouri Botanical Garden lists watering to a depth of 12 to 18 inches through late autumn while the ground is not frozen, a burlap wind barrier and organic mulch over the root zone. For frost it lists zone-hardy plants, avoiding low spots where cold air collects, no nitrogen fertilizer after July, and covering tender plants with cloth or paper instead of plastic before a hard spring freeze.

Look-alikes the sources name

The sibling page on sunscald covers dead bark on the trunk, and the page on frost cracks covers vertical splits. Road salt damage and drought stress can brown foliage in a similar way. The overview of weather, soil and chemical damage lists the rest.