When evergreens go brown in spring

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One spring, the face of each of these dwarf Alberta spruces turned suddenly brown. That side took the biggest hit one frigid evening in winter when the temperature plummeted. The arborvitae behind escaped damage from that wide temperature change, probably immune at a genetic levels. On the ground protected by snow is a juniper, a species that probably wouldn't suffer damage even in the open. 

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In late winter or early spring evergreens can change color overnight, the vestige of some cold, dry or windy time in the depths of winter. Like greens cut for holiday decoration, dead needles remain green for a long time. Then, when live portions of the plant begin to take up water once more, damaged sections cannot follow suit and become as brown as last New Year's wreath.

Please note this article deals with needled evergreens.
For browned-out broadleaf evergreens such as holly,
see Deciduous dieback.

You can jump to:
Why one plant, not another? 
Evaluating the damage  
What you need to know about buds
Damage to wood 
Taking in the big picture 
Assisting the plant in recovery

This season's examples:

You may see plants in your garden follow these three conifers' example:

  • A prized Hinoki falsecypress (below, left; a dwarf variety of Chamaecyparis obtusa) gave no sign during winter that it had been hurt by cold. Then in early spring its side facing the open sky became patchy brown.
  • A weeping red pine (center, below; Pinus densiflora 'Pendula') turned straw colored on its south face one day in March. The west side remained green, having been protected as it was gradually and gently engulfed by a shovel-raised bank of powdery snow. Had that snow bank been made with wet snow or compressed by a plow, the situation might have been very different -- hard packed snow is not a good insulator and broken branches would complicate the damage.
  • A dwarf Alberta spruce (below, right; Picea glauca 'Conica') that was green yesterday is suddenly red-brown on its most exposed surface (in Earth's northern hemisphere, that's usually the south-or west facing side).

ChamaeObtusN6758s.jpg PinusDSite8083s.jpg DwfAlbHintGrn7869s.jpg

Why this plant? Could the damage have been prevented?

Every winter, some evergreens burn like the dwarf Alberta spruces, red pines and Hinoki falsecypresses in our example. Yet others of their kind escape damage. (We're often very surprised by what's hurt, what's not.)  Sometimes the saving grace is wind protection, natural or otherwise, that keeps a site just a few degrees warmer on the coldest night. Or one plant may have an older, wider or more fortunate root system that enabled it to take up more water in fall. Perhaps the air is more moist, year round, because a property is near a large lake or in a river valley, which is to the benefit of species such as falsecypress.




Right: Were these yews damaged while others nearby were spared, because they are at the edge of the larger trees' canopy? If so, was the exposure to open sky more harmful, or were some portions of the yews dry because of competition from tree roots concentrated there at the dripline? We  are pretty sure salt/de-icers were not involved in this far-backyard bed. Beyond that we can only guess, improve growing conditions and perhaps add seasonal protection for very special plants.







Genetics can also complicate things when you set out to decipher winter damage patterns. Closely related plants may react very differently to environmental stress.

That's clear in this collection (right) of spruces: blue spruce, dwarf Alberta spruce and dwarf Norway spruce (right: Picea pungens, P. glauca and P. abies).

ChamaeObtusN6758s.jpg  As another example of relatives with varying
  tolerance: Hinoki falsecypresses (Chamaecyparis obtusa,
) are usually quite sensitive to cold and drought.
  It has much tougher cousins, such as Atlantic white cedar
  (Chamaecyparis thyoides) and the Sawara falsecypress (C. pisifera).


Below, left: Chamaecyparis pisifera 'Filifera Aurea', a gold threadleaf variety. It's one of the winter-tough Sawara falsecypress clan.

ChamaeMop8072s.jpg ChamaePisifDmg5076s.jpg ChamePisifTips5081s.jpg

Above, center: Yet genetics can be trumped by environment. Just a stone's throw from unaffected gold threadleaf Sawaras, a blue Sawara (C. pisifera 'Boulevard') took a hit, even though it has not before been damaged in winter.

Above, right: Like most evergreens, the falsecypresses do drop needles naturally each year. However, an attentive gardener knows that only old, interior needles should fall in that shed. This blue Sawara falsecypress tells us winter was tough because even the newest needles were killed on some branches. (Pruning will be in order.)

Live, learn, try to have fun!

When winter damage seems random it's probably only because so many factors can come into play, both natural and man made. It's the unusual gardener who can know just where the wind gusts a bit stronger or cold air settles sooner and remains longer to create a colder- or warmer microclimate. Unless we've done a drainage test in every part of a property we also don't know where the movement of air and water through the soil may be just a tad more lively -- there roots might function more effectively to replace water loss. Similarly, we are often completely unaware of some animals, insects, pesticides, barbeque grill fumes, pavement sealers and a thousand other variables whose actions may predispose a plant to damage.

Once we accept the immediate damage or loss,
working through these puzzles is often both engaging and educational.DwfAlbTwigN6721s.jpg

How bad is the damage?

Needles gone partly or wholly brown will fall off and that may create some bare spots. For the plant, this means a loss in energy. However, if the total foliage loss for the plant is less than one-third, the energy deficit can be made up and the spots may fill in a season or two.

More often, winter damage creates an aesthetic problem only the gardener can rate. If the plant has a vigorous growth habit, is in good health and has plenty of live buds in position to fill a gap, we might simply wait for natural fill. Perhaps we hasten the process by training branches to cover the spot or pruning to allow light to reach and bolster the growth of tiny remaining buds. Sometimes nothing will satisfy us but to replace the plant.


Right, above: All of the brown needles will eventually drop off this part of a dwarf Alberta spruce. At first, the only green we'll see will be from interior needles, and that will be overlaid by brown twigs.

Right: Yet all the buds on the branch are still alive and can leaf out if growing conditions are good. That fresh new green will quickly fill the gap. We pulled allthe needles from that first cutting to help you visualize the green to come. Needles will appear not only from each branch tip but from buds midway along the lower left twig.

Live buds are key -- learn to look for them

For most needled evergreens, recovery requires not only good growing conditions but live growth buds -- buds set the previous year. Buds often survive even when foliage dies since the embryonic growth inside a bud is less watery than foliage -- less likely to freeze. That new growing point is also insulated by a resin-filled cap.

Note: Leafy buds may survive cold that can kill
flower buds or flowers within leafy buds.
See Blooms lost to cold.

Below: Don't let the damage get you down. At left, the winter damaged dwarf Alberta spruce branch, a sorry sight. Below, right: The bud we cut open to check for signs of life. The buds were fine -- moist and green.

DwfAlbTips7870s.jpg DwarfAlbBud10xN6725s.jpg

Below, left: Two branches from the weeping red pine in our opening example. We took one branch from the exposed side of the weeping red pine -- most of its needles have gone brown. The other branch is from the more protected side of the plant. Both branches will eventually drop their browned needles.
Below, right: The good new is that both branches have viable tip buds.

 PinusDTwigsN6711s.jpg PinusDTipsN6713s.jpg


Right: A bud from the weeping red pine, cut open to check for life. Even if all the needles fall in the next few weeks, the branches will not starve from leaflessness. That's because each bud contains and will quickly deploy what's visible here: A new branch (1) and all its needles (2).


When wood dies

Winter may kill wood, too. Scratch to check for life -- live wood has moist green cambium under the bark. Prune out dead wood.

If its buds die, a branch of pine, spruce, juniper, arborvitae or falsecypress will almost certainly die. Cut out that weak wood. Keep only bud-tipped branches.



Below, left: The yew pictured earlier in this article lost not only its needles but the buds, too.
Below, right:
Even without cutting into a bud we know they are dead by comparing their color and firmness to buds on an undamaged yew.

YewDeadTip7902s.jpg YewLivTip7897s.jpg

Below, left: We scratch the damaged yew branch to determine how far we must clip to reach lively wood. The bottom branch of this pair is a goner. We'll prune out all such wood. 18 inches down on the limb we begin to find green needles and also green beneath the bark.
Below, right: By comparison, the twig of the weeping red pine is moist and green right to the tip.

YewScrtchdN6794s.jpg PinusDXsectN6714s.jpg

Keep your eyes openChamaeObtusN6758sa.jpg

Damage to ever-greenery may be what you notice first but don't stop looking there.

Register the burned needles on the falsecypress but don't quit there. Look at deciduous shrubs and bases of trunks, too, so you won't overlook other, potentially greater problems. (Here, 1, 2 and 3 mark deer-, rabbit- and vole damage.
Animal damage.)

Assist a recovering plant

Water and light are the most important factor in recovery. Do not allow the root zone of a recovering plant to go dry, and never let it become soggy.

Do what you can to let more light reach in to speed bud growth and strengthen interior growth. Prune overhead as necessary to increase light. Sweep the plant gently or hose it off to dislodge dead needles. Clip out some of the weaker twigs to reduce the shade they cast on deeper buds, and to redirect energy from those twigs to stronger growth.

You might prune the damaged plant to reshape it or increase its density, too. Whenever there are live buds on a branch loaded with brown needles, you can wait a bit before making pruning decisions.
See Deciding what to cut.

Once new growth begins, fertilize per a soil test or use a balanced fertilizer such as 4-4-4 or 10-10-10. Visit the plant regularly to head off any insect or pest problems.

About troubled broadleaf evergreens

We deal separately with needled evergreens and broadleaf evergreens. That's because most needled evergreens cannot regenerate from bud-less wood, and all pruning strategies, remedial and routine, must keep that in mind.

Yew (Taxus species) is an exception. It has needle-like foliage but is able to sprout from bare wood even when stumped to the ground.

Broadleaf evergreens can be pruned quite differently than needle evergreens because the broadleaf species will regenerate from bare wood. So in assessing winter damage, we treat them like deciduous shrubs. If you are assessing the damage on an azalea, Rhododendron, holly, Pieris, boxwood, Euonymus, etc.,
see Deciduous dieback.





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