I have two
Blue Atlas Cedars
(Cedrus atlantica 'Glauca')
that are completely brown after this winter. Are they dead or is the
foliage just burned?
atlas cedar is rated as hardy to USDA
Much of Allegheny County is listed as Zone 6a, with low winter
temperatures ranging from minus-5 to minus-10 degrees, but the City
of Pittsburgh Pennsylvania is rated as Zone 6b, with winter lows
from 0 to minus-5 degrees. Whether they live or not depends in part
on where you live.
If you are in an urban area, where buildings and
pavement hold more heat than suburban and rural areas, the foliage
may just be burned and they will survive. If you live in the
suburbs, especially the northern suburbs, they may not.
Any new growth?
New growth should begin to
emerge by the end of May
Established Blue Atlas Cedars vs. Newly Planted Ones
It also depends on how long they have been growing --
established plants have a better chance of surviving extremes than
those that are newly planted. Likewise, plants that go into winter
well hydrated and healthy will fare better than those that are
stressed by drought or insect and disease problems.
The role of wind
In addition to brutally cold temperatures, strong
winds play a role. While needled evergreens usually have a waxy
coating on their needles that helps minimize moisture loss, blue
atlas cedar needles are not as heavily waxed as many spruce and
Strong winds pull moisture through the stomata (pores) in the
needles, but plants cannot take up additional moisture from frozen
ground to make up for the loss. The result is the browning you see
on the foliage of your blue atlas cedars. This type of damage is
very evident on broadleaved evergreens such as English ivy,
euonymus, pachysandra and rhododendron.
Wait & See
The bottom-line with your blue atlas cedars: Wait
until they should start showing new growth as temperatures warm in
spring. The brown needles will drop and new growth will start
covering those bare branches if the foliage was just burned. If that
does not happen, then they did not survive the polar vortex.
The revised USDA Hardiness Zone map and climate
change have many gardeners pushing hardiness zones with plants that
are marginally hardy for us, including crapemyrtle, camellia and
photinia. That is fine, as long as losing these tender gems to a
harsh winter doesn't break the bank. Again, some of these plants
might die to the ground and come back from the roots, so do not be
in hurry to dig them up. Give spring a chance to finally arrive and
see if they show any signs of life, especially crapemyrtle -- it is
very slow to come to life in spring.
Click on map to enlarge
Other winter damage
Even plants that are generally hardy to Zone 5 may
show dieback or other signs of damage when spring arrives.
Spring-bloomers such as forsythia, big-leaf hydrangea and evergreen
azaleas may only bloom close to the ground, where flower buds were
protected by snow cover. Be patient and see what spring brings.
Freeze Damage to Outdoor Plants
Winter garden beauty