Few things are worse than losing an established, favorite shrub
to winter's vagaries but sometimes it happens. Don't make it worse
by overlooking the situation. Acting early is often the key to
saving a winter damaged plant. And when the plant's not
salvageable, acting early means a replacement plant will have that
much more gentle spring weather for its settling-in.
To jump along:
• Check buds, do a scratch test,
• Check for breaks and chews,
• Cut sooner rather than later,
• Broadleaf evergreen, same as
deciduous.
Below, and right: Roses grow very quickly and bloom well on
new wood (hybrid teas) or from canes older than one year but not
too old (climbers, shrub types). They also tend to have a lot of
dieback each winter. So when everything you see on your rose in
spring is shriveled and discolored from freeze-drying, why worry
about what to cut? Cut it all! See more in Mentors' Spring
chorus: Cut weak wood hard.
Check buds and do a scratch
test
Check shrubs and trees for flexible wood with live buds.
Sometimes dead wood is very obvious but don't rely solely on your
eyes, because freeze-dried tissue can look good even in death.
Scratch a stem to see if the cambium beneath the bark is moist and
green. Slice a bud or two and look inside for moist, green
tissue.
Below, left: Golden Vicary privet is likely to die back in a
very cold winter, if the cold comes before it has finished
hardening off in early winter or as it's resuming growth in spring.
We expected to see dieback this spring but the buds we've checked
are plump, green and ready to go.
Below, right: Rose of Sharon (Hibiscus syriacus) is also
inclined to die back in very cold winters. This year it seems to
have escaped damage. Its growth buds are tiny and embedded in the
branch so they are difficult to show to you, but that moist green
beneath the bark is undeniable proof of life.
Below: The tissue inside these kousa dogwood buds is still
moist but the discoloration at the base of the flower bud (arrow)
is a pretty good indication that it will abort before bloom time.
Leafy shoots and buds often survive even when flower buds are
killed by cold. See Blooms lost to cold.
Check for breaks and
chews
Look for breaks in main branches where snow plows or heavy snow
and ice came into play. Broken limbs may retain live buds and
scratch green but their growth may be weak or die back to the break
as soon as the plant is stressed.
If a break is recent (moist), clean enough to be re-set straight
and can be securely splinted -- all before budbreak -- that wood
may knit over time.
Check the base of canes and trunks for chewing damage. Hungry
rabbits and voles (meadow mice) often gnaw through bark to eat the
starchy green cambium. Right: Rabbit chews. See also Animal
damage.
Cut losses sooner rather than
later
If you find dead wood, dead buds, broken or badly chewed trunks,
don't wait. Cut to leave only good wood. This gives the plant the
chance to sprout from below the cuts during spring when weather and
plant hormones are most supportive of new growth.
Buds already in place dominate, suppressing the development of
new buds from lower on their branch. So if you want more density
from a tree or shrub it pays to prune some canes more
aggressively.
For more, see Deciding what to cut.
Right: The canes of this hybrid tea rose have been
thoroughly chewed by rabbits. Yet it's not a loss. It will come
back like gangbusters from below the cuts, if those are made to
healthy, green, white-center wood, even right at the graft. That's
at ground level here, where the graft was set several inches below
ground level for permanent protection. (Thanks to cold zone
gardeners including those at Hamilton Royal Botanical Gardens in Ontario,
for leading the way in this effective technique.)
Broadleaf evergreens,
deciduous species: All the same now
Deciduous shrubs usually drop all their leaves each fall and
replace them in spring. Broadleaf evergreens
(Rhododendron, boxwood, holly, etc.) retain leaves for
several years, adding some new foliage every spring.
In a tough winter that kills a broadleaf's foliage, the plant
faces an unusual energy deficit yet it can grow all new leaves.
Healthy, well established shrubs have the most energy in reserve
and so come back most quickly.
Below: Most species of that classic hedge plant, privet
(Ligustrum species) are deciduous. Some are
evergreen in warm regions. 'Golden Vicary' is a hybrid between
evergreen L. ovalifolium and deciduous L.
vulgare. It often holds leaves through winter. It
always replaces all of its foliage each spring. Other broadleaf
evergreens can do the same after occasional defoliation or hard
cutback.
