Winter has arrived in our valley.
The temperature was been well below freezing for quite a few
days. The ground is frozen. Jim tried to drive a shovel into
the ground, but it was impossible. We are hoping for a thaw
next week, so a few more grasses can be dug.
So this would be a good time to discuss the winter care of
ornamental grasses. I realize that it is rather late for some
of you while for others you don't even have to worry about cold
Ornamental Grasses in the Winter
|Saccharum ravennae on a
wet day in November
Jim suggests that the grass garden should not be "put
to bed" (cut down and cleaned up) for the winter. To enjoy
the 4-season interest that grasses can often supply, leave them
standing. Depending on your climate some grasses will remain
standing all winter. Wet snow is heavy and will cause some grasses
to keel over.
Calamagrostis x acutiflora
'Karl Foerster' will remain green through the early frosts
and the blossoms will remain upright until a heavy snowfall
takes them down. If you want to cut any for dried arrangements
be sure to get to them before that snowfall!
Miscanthus may remain upright
all winter. Saccharum ravennae (we
will be carrying it in the spring) is a very strong plant and
is unlikely to be taken down by mere snow! Its 10-15' tall blossoms
add wonderful interest to the winter garden.
Protecting Ornamental Grasses in the Winter
We sell grasses that are adapted to cold climates and should
survive Zone 3 and 4 winters without any problem. However if
your climate is severe and you want to ensure the survival of
your grasses you may want to mulch some of them. Snow is an
excellent mulch, but if you don't have it yet, then you need
to use a substitute.
The very best is compost and/or shredded leaves (not from a
Black Walnut tree). Both will feed the soil in the warm season
and both are light and airy enough to allow oxygen to reach
the soil. Neither will they become compacted, preventing oxygen
from reaching the soil. Straw or hay is also very good. though
there are seeds in hay.
Apply mulch to the moisture-loving grasses including sedges
and rushes. For those of you who do not already know, sedges
(Carex) and rushes (Juncus, Luzula) are not actually in the
same family as grasses, though they are generally lumped under
the term Ornamental Grasses.
One of the benefits of applying winter mulch is that the soil
maintains a more constant temperature. The freezing at night
and then thawing during the day can cause many small or shallow
rooted plants to be heaved out of the soil. This leaves their
root systems exposed and resulting in injury or death. Mulching
reduces the chances of heaving.
Some of the smaller dryland grasses and the prairie grasses
do not tolerate mulch close to their crowns. The constant moisture
will cause rot. Dryland and prairie grasses include the Fescues,
Koeleria, Andropogon, Panicum, Sorghastrum, Schizachyrium and
When to Apply Mulch to Ornamental Grasses
|Hmm, I see a nice cozy place
to hunker down for the winter...
Mulches used to protect tender plants from the ravages of
winter temperatures should be applied late in the fall after
the ground has frozen but before the coldest temperatures arrive.
Mice and other rodents are looking for a protected place to
spend the winter. If you apply mulch before it freezes you have
created a nice home for them! But if you wait to apply it you
should prevent this problem as, hopefully, they will already
have found some other place to nest. That said, we haven't found
mice to be much of a problem for ornamental grasses.
Mulching too early will also contribute to the possibility
Hardiness of Grasses
From our website:
Cold temperatures are only one of may factors that influence
the hardiness of grasses. Other factors include:
- how long the cold lasts - cell damage from freezing can
repair, except when the cold is prolonged
- the snow cover - snow is generally good for insulation,
but if it is icy oxygen is prevented from reaching the soil
- how moist the ground is - many grasses suffer more from
too much winter moisture than from winter cold
- summer temperatures - if there is plenty of heat the plant
will store more sugars and therefore have a greater resistance
- microclimates - low places are frost pockets, increasing
the exposure to cold temperatures
- freeze-thaw cycles - these can create the icy snow conditons,
or can trick plants into breaking dormancy too early
If you would like to reprint any of this information, the answer
is usually yes -- but please contact us
first. We ask that you include a link to our website and
mention the source of the information.
From a cynical gardener:
"Zone hardiness" -- The part of the country a plant
is most likely to die in.
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