In the six
weeks before the first hard freeze (i.e., down to about 25 F. at night), give
your roses a weekly "potassium feast" in each of those six weeks.
Potassium blocks the growth-promoting effects of nitrogen and
phosphorous, thereby hardening the canes in time for winter. I've been
doing this for more than 20 years and I honestly can't remember the last time I
lost a rose to winter weather here in Minnesota. Of course, I do other things to protect my roses from the Minnesota winter, as well. Here is my recent article on winter protecting your roses: http://jack-rosarian.blogspot.com/2013/09/winter-protecting-your-roses.html
Here is a
quote from Burpee’s American Gardening Series book Roses, by Suzanne Frutig Bales:
“Potassium
is an important mineral for sturdy stems and foliage. Weekly feeds of a gallon of liquid
potassium (1 tablespoon of muriate of
potash (0-0-62), dissolved in 3 gallons of water) per bush, or a granulated
feeding of potash magnesium (0-0-22), during the six weeks before the bushes go
dormant, will give the bushes an additional boost for winter, extending their hardiness into
another hardiness zone, perhaps two. Excess
potassium, when available in greater amounts than nitrogen and phosphorus, is
known as the ‘potassium feast’. It
will block the growth-promoting effects of nitrogen and phosphorus, hardening
the canes in time for winter.”
To clarify: The proportions are: 1 TBP Muriate of Potash per
3 gallons of water (or 1 TSP per gallon).
So mixing in a 30 gallon trash container, you would use 10 TBP. Apply one gallon of this mixture on each rose
every week. That’s not very much, but
remember you’re repeating it six times.
I begin
my roses’ potassium feast in the second or third week of September. That takes me through the end of
October or beginning of November, which is about as late as I want to go. There have been years, perhaps when I
started a little too late, that I’ve had to thaw out my hose or turn off my
water and turn it back on again in order to complete the sixth treatment. My advice is don’t wait too
long, because it’s better to be too early than too late with this.
Here are a few pictures of yesterday's application, taken by Mary Eileen (a.k.a "The Head Deadheader"):
Each rose gets one gallon of the mixture for six consecutive weeks. It has the added advantage of hydrating the plants weekly as we head into winter. Note that it was a very nice day yesterday; a lot nicer than it has been for many of my sixth applications.
Here I am with the 64 gallon container working on four of my Buck Earth Song plants.
I get Muriate of Potash (0-0-62) in 50-pound bags at Waconia Farm Supply, which is exactly 10 miles past the Minnesota Landscape Arboretum in Waconia. A 50-pound bag of Muriate of Potash costs about $25 and lasts me five years or more. For those of you outside of Minnesota, you will need to find a real farm supply store because it's pretty unlikely that you will find Muriate of Potash at your local nursery.
I get Muriate of Potash (0-0-62) in 50-pound bags at Waconia Farm Supply, which is exactly 10 miles past the Minnesota Landscape Arboretum in Waconia. A 50-pound bag of Muriate of Potash costs about $25 and lasts me five years or more. For those of you outside of Minnesota, you will need to find a real farm supply store because it's pretty unlikely that you will find Muriate of Potash at your local nursery.
After
about the third-week’s application, you will begin to notice that the canes of
your roses are turning a pretty shade of deep red, so you can actually see them
hardening-off for the winter, which is fun to watch.
I believe
that this method of winter protection is particularly interesting for northern
gardeners, as we see the continuing effects of climate change in the rose
garden. While putting on liquid-potassium for six weeks seems to be a lot of
extra work, I think it can ultimately reduce the overall work of winter
protection, once you gain confidence using it in your own garden.
http://jack-rosarian.blogspot.com/2012/08/potassium-special-k-ration-feast-for.html
http://jack-rosarian.blogspot.com/2012/10/potassium-follow-up.html
http://jack-rosarian.blogspot.com/2013/09/winter-protecting-your-roses.html