Roses in zones 5b and under need winter protection of
some sort. Here are pointers to consider depending on
where you live and what roses you are growing!
Late October to mid November is the time to put your roses to bed in zones 5b and under. The
aim is not too soon nor too late but just at the right time.
This is a time that most rose growers detest -- winterizing the roses. It's not enough for us to
have to acknowledge that there will be no more blooms until spring but the actual job of
putting our babies to bed is not an easy one especially if you've a great number of them and if
you live in a cold climate!
Here are some guidelines to help you understand why it's needed and to get your through the
process; hopefully making it somewhat easier to swallow.
- For a rose to survive winters not only does buying a hardy variety
come into play but the process of acclimation and de-acclimation is
crucial!
"What da heck" you say is that?? Well stay tuned and you'll find out....
One year you plant a hardy rose that is said to survive to zone 4 (you're zone 5b- warmer)
and the next spring you've had massive cane damage and you're left wondering "why?”
In order for hardy plants to get through winter successfully they must go through a period
of acclimation (fall) and then de-acclimation (spring). This process allows the plant to undergo
certain chemical and physiological changes.
Plants that have the ability to do this have obtained it from their adaptation of their cold
environment over millennia. Yes, Evolution plays a very important part in this scheme of
things. So either a rose has super-cooled genes or it doesn't. This explains why some roses
are hardier than others.
Acclimation occurs in late fall as the plant responds to the shorter day length (less & less
sunlight) along with colder temperatures. If the days continue to get shorter as they do and
the temperatures continue to get colder by early winter the plants have shed enough water
from their cells so that they can withstand freezing temperatures without perishing. Some call
this "super-cooling".
What then happens if you have fall into early winter when the temperatures don't continually
get colder but stay relatively warm then all at once dive to well below freezing OR Winter
arrives early before the plants have had sufficient time to acclimate??
The answer is that you get winterkill. Whatever part of the plant that has not sufficiently
shed water from its cells has died. It's quite simple; too much water in a cell and when it
freezes it expands and the cell wall burst.
In spring the plants will begin to de-acclimate triggered by the day length getting longer and
the temperatures steadily rising. This means their cells will slowly begin to accumulate water
until they are back to full functionality.
So what do you think happens when you've had a very warm early spring (January frost) but
then winter decides it's not over yet and temperatures dive again to below freezing??
Winterkill also. If this happens early in the de-acclimation process the plants still have the
capability acclimate but if it happens late in the process, the plant can get to a point of no
return.
Something similar to this can happen if you leave your rose cone on without propping it up
in warm days of early spring. It gets warm enough in there to fool the rose into thinking its
spring and it de-clematises and breaks dormancy. When a really cold spell descends it's past
the point of no return and the plant dies.
So you see Mother Nature will have the last say every time and we humans just have to
acknowledge and accept it
Here, it is still too early to put the final touches on the rose beds as the mice can still decide
to make their winter homes in the winterizing materials and feed on their favorite food- rose
roots and bark! So I have to wait until mid to late November before I can finally put them to
bed. But for gardeners in colder zones here's what I will do:
Most gardeners to seem to think we have it easy here in the Central Nova Scotia area
where I garden and I'm quick to alert them to the hazards of living in a temperate zone
against an ocean that keeps our temperatures quite warm for way into December making
our roses not want to go dormant thus making them very susceptible to winterkill. The
constant freezing and thawing, icy rains coupled with very little snow makes me want to pack
up and move back to my native Northern New Brunswick home where snow had insulated
and kept my roses snug as a bug in a rug all winter!
So , I will mound and cover hundreds of plants with earth and lots of leaves gathered from
every friend and neighbor willing to part with them. Evergreen boughs are used to hold the
leaves down and make the garden look neat and tidy. The trick is to keep the roses at an
even keel of a frozen dormant state until spring. You don't want them to break dormancy
too early or during a January thaw.
If you have roses that are tender or your not sure if you should mound them or not-A good
rule to live by is if unsure mound them anyway!! It could mean the survival of that special
rose you mightn't be able to replace again. Mounding can help ensure the survival of any
buds below the earth mound that will develop into new canes in spring. So don't wait do it!!
