Protective Winter Mulch
A mulch is any material that is spread on the ground to help foster plant growth. Most
gardeners are familiar with using mulch for weed control and water retention, but mulching for
winter protection is different. Since the Anchorage area does not always have reliable snow
cover throughout the winter, mulching makes perfect sense. However, surprisingly few Alaska
gardeners take advantage of this technique to provide extra protection.
Purpose and Methods
The purpose of mulch is to moderate
temperatures and keep the ground frozen,
not to keep the ground warm. Alternating freeze
and thaw cycles wreak havoc with perennial
plants.
contains broad-leaved weeds, but also be on the
lookout for grass seeds. Having barley or oats
sprout up in your garden all summer can be just as
distressing as losing plants to cold temperatures
and desiccation.
Mulch should be applied after the ground
freezes, but before a lasting snow. In Alaska,
this can be tricky but winter mulch usually is
best applied in October. Mulching too early
can result in rodents setting up residence in
your flower beds. Mice and voles are usually
the most devastating to trees and shrubs, but
they can also eat bulbs or destroy the crowns
of plants.
The thicker the layer of straw the better. A
minimum of six inches is recommended, with
10 -12 inches ideal. It may be cost prohibitive
to mulch your entire garden this thick, but don’t
skimp on depth. If you don’t have enough straw to
mulch everything, select certain plants and mulch
them well. These may be a species you lost last
winter, or new plants you’ve never tried.
For ease in applying and removing mulch, it
is best to cut down the stems of taller plants.
Definitely remove the foliage of diseased
perennials before mulching. Powdery mildew,
gray mold and white mold can be very
troublesome late in the summer.
Appropriate
Mulching Materials
A winter protective mulch needs to have
good insulating properties and not create
more problems than it solves. Straw makes
a good insulator because its hollow stems
trap air. When purchasing straw for mulch,
it is critical that it not contain weed seeds.
You should be able to easily tell if the bale
Gardeners like to use leaves for mulch, but they
don’t have the same insulating quality as straw.
They tend to mat down and turn into a block of
ice. Leaves are free and easy to obtain, but they
should be used with caution.
Evergreen boughs make an excellent winter
mulch. They don’t pack down and help to collect
and hold snow in place. They can also be
used on top of straw to prevent it from blowing
away. Spruce boughs are easy to come by if you
have a lot of trees. If you don’t, boughs may not
be an option. Also, fall is the recommended time
to prune the lower branches of spruce in an effort
to make trees less susceptible to spruce bark
beetle infestation.
Removing Mulch
If you decide to apply a winter mulch, think about
how you will remove it in spring. Mulch should be
removed when the grass first starts to turn green.
Evergreen boughs are the easiest to remove.
Just lift them off and pile them somewhere in
the yard. It would be ideal if you could run them
through a chipper to be used as summer mulch.
Use a pitchfork to remove straw and then rake
gently with a leaf rake. Straw can be stockpiled to
use again next winter if it doesn’t decompose too
much. It can also provide an important source of
carbon for your compost pile to help offset high
nitrogen lawn clippings. Straw can also be used
as summer weed control as mulch between the
rows of your vegetable garden. Using straw for
weed control in the flower garden is more difficult.
A thick, 10 - 12 inch layer is needed to prevent
light from reaching the soil surface and to keep
weed seeds from germinating.
Leaves can be removed in layers as the outer
leaves start to thaw. Since leaves tend to
decompose quickly, they are the easiest to
remove and used either in the compost pile or
around the base of perennials.
Mulching Containers
with Perennials
Perennials in containers, which should be hardy
enough to survive the winter outside, need
special care too. Containers can be buried in
the vegetable garden or grouped together, tilted
on their sides so they don’t collect water, and
then mulched. Don’t just cover the tops of the
containers. The roots also need to be protected
and containers should have a thick layer of straw
or leaves packed around them. Remember clay
pots absorb water and can chip and crack over
winter.
Inappropriate
Mulching Materials
Worthwhile Effects
There are many mulch materials that do not
provide good winter protection. These include
grass clippings, wood chips, plastics, or floating
row covers. Row covers could be used to hold
straw in place if you live in a windy location.
Conversely, straw can be placed on top of row
cover to make removal in the spring easier.
Is winter mulching worth the extra work and
possible expense? For many species a protective
mulch can be the key to winter survival. The
use of a winter protective mulch is not unique to
Alaska. Northern gardeners across the country
go through this annual ritual of preparing their
gardens for winter.
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Rev. 9-2014