The Zone number indicates the coldest zone in
which we believe the plant will survive. This is based
on USDA specifications, our own and customer's experience
with the plant and/or data regarding where the plant
is native to. The lower the number, the colder the
zone. So if a plant is hardy to Zone 3, it will grow
in very cold climates!
If you are not sure of the zone that you are located in, please
refer to the following:
Canada:
Hardiness Zone Map - Canada - 2000 data
Note: you need to click on the Legend link on the
left, or order to make sense of this. Easy to zoom
in for the complicated Zone situation in BC
USA:
Hardiness
Zone Map - USA
The zones actually blend into each other, and within each zone
there are microclimates that can be colder or milder than the
surrounding area. Use the map Zone information only as a guide.
Cold temperatures are only one of many 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
to stress
- wind
- 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
With so many variables we think it is more useful to talk
about our growing conditions (see the write-up with each individual
plant). We can usually count on having Zone 4/5 winters for our
hardy field grown plants, but with so many "record breakers"
lately it is hard to know what to expect. One advantage is that
grasses and willows tend to survive, when many other plants succumb.
 |
Miscanthus purpurascens does
well in cold climates |
That said, we would also like you to know that as a nursery we
feel a need to be cautious in regards to the Zone listing. Through
feedback from our customers we are aware that many grasses have
survived and indeed thrived in climates much colder than we are
listing. Here is an example:
"I've actually grown Chasmanthium
latifolium successfully in two Winnipeg gardens, one
north facing, the other south facing. It did better in my north-facing
garden, I think because it was in a raised bed and had good
drainage .... it has survived a very cold winter here - last
year was the coldest winter in 80 years.... The two others I've
used a lot are the blue fescue....
and Helictotrichon sempervirens,
which is listed as zone five...."
E. Jones, Winnipeg, Manitoba, Canada, Zone
3
"Miscanthus
purpurascens does fine here too, as does all Calamagrostis
(Foerster and Overdam), ribbon grass
and fescues."
Customer in Saskatoon. SK, Canada, Zone
2
You may be able to create microclimates that allow you to grow
more than the zone listed or you may find that seemingly inexplicably,
a plant has died when it should have been fine in your zone. The
zones are a good starting point, but you still need to determine
for yourself what will and won't work in your garden.
How to push the zones:
- give adequate care during the growing season
- protect for 3 to 4 seasons and the chances of the plant surviving
without further protection are greatly increased
- mulch heavily
- be sure the plant is dry when mulch is applied, or it
may rot
- create a microclimate
- plant near a brick or stone wall, particularly on the
south side
- avoid planting in low areas
- screen from from wind
- avoid planting where water collects in the winter
- don't cut down in the fall
And most important - a healthy plant has
a much better chance of surviving the winter than does a plant
whose needs have been neglected.
- give the plant the amount of water it requires during the
spring, summer and fall.- don't let it get too dry and don't
drown it
- make sure it isn't crowded or shaded and therefore not receiving
enough light
Any more suggestions? E-mail us!
The University of Minnesota did a winter hardiness study of ornamental
grasses. The results are available online
and in their wonderful book Ornamental
Grasses for Cold Climates. |