Winter-Protecting Your Roses
Jack Falker
@mnrosegardener
Everyone in Minnesota knows they have to do something to
winter-protect their roses. However, not
everyone seems to know exactly what they’re supposed to accomplish and, thus,
what the best method might be. So let’s start with the one
basic principle that applies in all cold zones, i.e. USDA Zones 3, 4, 5 and
parts of 6, and to virtually all types of roses, whether they be hybrid teas or
shrubs; grafted or own-root.
Fact: The primary objective of winter protection in
the cold zones is to keep your roses frozen, not to keep them from freezing. There
seems to be a lot of confusion about this and, unbelievably, we still have
nurseries selling styrofoam rose cones, which serve as little ovens in the
winter, when the sun shines on them, causing plants to freeze and thaw
repeatedly, thereby killing them.
There are two basic ways of
keeping roses frozen where we live: (1) the Minnesota Tip and (2) mounding with
compost and insulating with leaves or hay.
Let’s be clear about the “tip” method:
When you tip your roses over in a trench, bury them in dirt and compost,
and put leaves on top, they are definitely going to freeze solid in the ground,
as the frost permeates down several inches. In fact, many Minnesota-tippers
soak their tipped roses, before turning off their water for the winter, so they
will be contained in blocks of ice. In
other words, the objective of the “tip” method is to freeze roses solid and
keep them frozen until spring
I personally believe that keeping
my roses standing upright and firmly planted, while mounding and insulating them,
is the best way to winter-protect. I tipped my roses for many years but always
felt that it was not horticulturally sound to partially uproot the plants and
cover them with dirt in mid to late October, when many of them were still in
bloom. The longer I did it, the more my gardening instincts (not to
mention my back) kept telling me I should be doing something
different. Take a look at my August 2012 Minnesota Rose Gardener blog
post "No Tipping Please”:
Many people, who have been tipping
their roses for years, feel trapped in the procedure because the bud unions of
their grafted hybrid teas are above the surface of the ground. This is a
basic problem, which is endemic to the tipping procedure. For a variety of sound horticultural reasons,
the bud unions of grafted roses and the crowns of own-root roses should not be
above ground, regardless of where you live, warm or cold. My advice to these
folks is: Instead of tipping your roses this year, dig them out entirely,
taking a good root ball, heel them into a trench, a foot or so deep, and cover
them with a good layer of dirt and mulch (to keep them frozen). Then in
the spring replant them in the same place, except this time plant them with the
bud unions several inches below the surface. If your garden is large, you
might do this in stages, some this year, some next year etc. Another
alternative might be to raise the level of soil in your beds so that your bud
unions are at least slightly below grade.
With your
roses properly planted, here is what I recommend for winter protection. First,
in mid-September and for six successive weeks, give your roses a potassium
feast to help their canes harden off, before the first hard freeze. It’s too late to start the feast this year
(I’m about to do my fourth application) but I believe potassium is important in
winter protection. For future reference,
here is the address of my most recent blog on the potassium feast:
Next,
gather any wood chips or other clean mulch in your beds and mound it around
your plants. Then, mound several shovels
of compost around every plant, so that the plant crowns are thoroughly covered.
My compost is primarily shredded oak leaves from last fall and hundreds
of pounds of composted Starbucks coffee grounds that I collect regularly. This
compost is full of worms and worm castings, so it's just what the roses need in
the spring, when I spread out the mounds and work the compost into the ground.
Next,
when it starts getting cold and your roses have stopped blooming, cut them down
to about 12 inches and bind them into tight bundles. One other thing you might
do, especially if you’ve had spider mites this summer, is to strip the leaves
off the plants and spray them with horticultural oil. (Don't worry, you're not
losing anything here; what you want is the strong new growth you’ll get in the
spring.)
The final
step is to prepare enough half-full plastic leaf bags to cover each of your
roses. (Don't use the new compostable bags; they break down over the
winter and leave you with piles of leaves to clean up!) Now, wait until
the ground freezes and, with the objective of keeping your roses frozen, slit
open the bottoms of your leaf bags and shove them down over each of your tightly
bundled plants, flush with the mounds.
So, can
you see how this approach will keep your roses frozen? When you start to
carefully roll the bags off your roses in the spring (to keep as many of the
leaves in the bags as possible for disposal or mulching), you will
find that many of the bags are still frozen to the mounds and that your roses
are encased in blocks of ice; exactly as you wanted them to be. In fact,
depending on how quickly it warms up, it may actually take longer for these
mounds to thaw than roses that have been tipped.
Regardless of how you choose to winter-protect your roses,
please keep firmly in mind that your objective in the cold zones is to keep them
frozen all winter. The other alternative, of course, would be to move to a warmer
zone, where your objective would be the opposite, i.e. to keep your roses from
freezing in the first place. No such
luck for me!
Jack Falker (@mnrosegardener)
10/01/2015
