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Winter Preparation for Ornamental Plants

November 26, 1997
This winter seems to have crept up on us before we realized
what was happening. Many of us
were not able to prepare our plants the way we normally
would. Although we are past the ideal
time for many preparations, there are several items you
might still consider to prepare plants for the
depths of winter.

Needled and broadleaf evergreens are susceptible to
winter burn caused by desiccation. This
occurs when frozen soil reduces water absorption while the
plants are exposed to drying winds and
deicing salts. Needles or leaves typically begin to turn
brown at the tip and brown further
backward, depending on severity. One way to help prevent
rapid moisture loss through the leaves
or needles is with antitranspirants, which help reduce
transpiration. Antitranspirants should be
applied now‹before severe winter sets in.

Other types of cold injury include sunscald and frost
cracks. Sunscald and frost cracks are
caused by extreme temperature fluctuations. Sunscald is
actually a freezing injury and is most
likely to occur on young trees. Sunscald spots may develop
into a frost canker. Use tree wraps on
susceptible trees to help reduce the risk of damage from
temperature fluctuation.

Frost cracks occur when the outside cells of the tree
lose water, shrink, and pull apart‹causing a
crack to open longitudinally with the grain of the wood.
Again, tree wraps may help, but some
species are simply more prone to cracking than others. Trees
shaded on the south and west sides,
where the tree heats up the most, will sometimes crack less.

Roses typically need additional protection, and it is not
too late to cover them. Ideally, excessively
long canes of hybrid teas, floribundas, grandifloras, and
polyanthas should have been pruned back
slightly by now. Because the plants should be covered after
they go dormant, do that now. Bushel
baskets or commercial covers work well. You will need to
trim the canes back to fit underneath the
cover. Other ways of protecting the roses include covering
with leaves (oak work best), pine
needles, straw, old sawdust, or bark chips. The depth of the
material should be 12 inches. Soil is
not recommended as a cover because it stays too wet and
packs too solidly. In the spring, remove
the cover or mulch, trim the canes back to healthy wood
(just above the strong bud), and thin the
plants to four or five canes.

Climbing and rambling rose canes may also need winter
protection. Lay the canes on a bed of
straw and cover them with more straw. Be sure to cover the
crowns. Keep the straw in place by
tying it or covering it with a small amount of soil. In the
spring, remove the covering, remove all
damaged wood, and place the canes or shoots back on the

Because of our late fall, many trees did not drop their
leaves until recently. If possible, you should
still try to remove the fallen leaves‹particularly
because leaves left on the ground could damage
grass. Additionally, many leaves house pathogens capable of
causing disease the following year.
Dispose of leaves through community programs or use them as
mulch or in a compost pile. Check
with your local law enforcement agency or fire department
before burning leaves, because many
local governments prohibit leaf burning.
In summary, the more work done through the fall and winter,
the less spring cleanup will be
required. Be sure to properly discard all plant wastes. Do
not remove winter-protective devices too
early in the spring. In areas subject to many late heavy
snowstorms and temperature extremes,
early mulch removal might be a serious mistake.

For more information, obtain the horticulture fact sheet
Winter Protection for Woody Plants,
# LH 179.

Author: Rhonda Ferree Jim Schmidt


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