Winter Protecting Your Roses

Well it's 92 degrees in Minneapolis today;  so it's a great time to talk about winter protection!

What you do for winter in your rose garden depends a lot on where you live, of course, but one basic principle applies if you live in a cold zone, i.e. USDA Zones 3, 4, 5 and parts of 6.  Your objective is to keep your roses frozen; not to keep then from freezing!  There seems to be a lot of confusion about that and thus we 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.

But before we discuss actual protection methods, here's something everyone in the north should consider doing about six weeks before your 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.  Take a look at my article: "Potassium: A Special K-Ration Feast For Your Roses", published in August 2012:

http://theminnesotarosegardener.blogspot.com/2012/08/potassium-special-k-ration-feast-for.html as well as my follow on article that shows the effect of the potassium on the plants: 

http://theminnesotarosegardener.blogspot.com/2012/10/follow-up-on-potassium-feast-and-air.html

So, after your roses are hardened off, what's next?  As those of you who have read my previous articles know, I am not a believer in the "Minnesota Tip".  I tipped my roses for many years but always felt that it was not a horticulturally sound practice to partially uproot your roses and cover them with dirt in mid to late October, when many of them were still in bloom, i.e. not even close to being naturally dormant.  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 blog post:  "No Tipping Please!":

http://theminnesotarosegardener.blogspot.com/2012/08/no-tipping-please.html .

Besides being horticulturally unsound, the best reason I can think of for not tipping your roses is that it's simply unnecessary, unless you live well north of the Twin Cities, and even then I believe there are better methods (which I will discuss below). Take a look at the chart I developed, using Minnesota Climatology records, showing the progression of extreme minimum temperatures (EMT) in every winter since 1963.  As you can see, in the last 17 years there have been only four winters that have fallen in Zone 4 and, studying the climatology records more closely, those deep-freezes lasted only a couple of days, compared with winters in the 60s and 70s, when the deep-freezes lasted for weeks at a time, with daytime temperatures not rising above zero Fahrenheit. Now look at the slope of the trend line, moving steadily upward toward Zone 6, and note that nine of those 17 winters have actually been above the median of Zone 5, making them closer to Zone 6 than Zone 4.  So, why protect your roses for Zone 4 winters when our winters are approaching Zone 6, especially when you consider that your task is just to keep your roses frozen?

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 at or above the surface of the ground.  My advice to these folks is that, 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 five or six inches below the surface.  If your garden is large, you could do it 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.

Once your bud unions are at least somewhat below grade or, even better, if your roses are growing on their own roots, here is what I recommend for winter protection.  Year-round, mulch your beds with at least three inches of wood chips overall, and in the late fall pull more of those chips up around your plants from the area surrounding them, so you have five or six inches of chips around every plant (in the summer fewer chips are desirable around the plants, to work in fertilizer, coffee grounds etc.).  Next, mound a couple of shovels full of compost from your mulch pile around every plant.  My mulch pile is primarily shredded oak leaves from last fall and hundreds of pounds of composted Starbucks coffee grounds that I collect regularly.  See "Coffee Grounds and Roses":
http://theminnesotarosegardener.blogspot.com/2013/03/coffee-grounds-and-roses.html.
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 wood chips and work the compost into the ground.  

Next, when it starts getting cold and your roses have stopped blooming, bind them into bundles and cut them down to about 12-18 inches. (Don't worry, you're not losing anything here; what you want is the strong new growth you will get in the spring.)  Here's what this looks like before I cut them back: 

Also, see "The Big Coverup":
 http://theminnesotarosegardener.blogspot.com/2012/11/the-big-coverup.html

The next step is to prepare a bunch of half-full, regular plastic leaf bags.  For heaven's sake, don't use the compostable leaf bags (as I did one winter, picking them up from neighbors' leaf bag piles).  They break down over the winter and leave you with piles of leaves to clean up!  When you put these bags on your roses will differ, depending on where you live.  In zones 3, 4, 5, and colder parts of 6 (like Chicago), wait until the ground freezes before putting them on.  Now, with the objective of keeping your roses frozen, one-by-one slit open the bottoms of your leaf bags and shove them down on each of your plants, flush with the mounds. In higher cold zones, i.e. warmer parts of zone 6 (like Detroit, Cleveland, Kansas City, Indianapolis, St. Louis, etc. you can probably just rely on the mounding and wait to see if you get snow cover to insulate your beds.  If not, I would put the leaf bags on the plants in the latter part of December, as a precaution against freezing and thawing.  

So, can you see how this approach will protect your roses just as well as the "Minnesota Tip"?  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 the 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 take longer for these mounds to thaw than the tipped roses.  In March of 2012, we had a very early warm up into the 80s and the beds began to thaw, such that it appeared that it was time to take the bags off the plants.  I was suspicious that it could get cold again and, thankfully, I just rolled the bags back a little to allow the plants to start thawing.  Sure enough, in a few days, night-time temps dropped into the teens and I was able to push the bags back over all the plants to insulate them from the cold snap.  The apple trees all over southern Minnesota and the cherry trees in northwestern Michigan had all bloomed, and substantial parts of both crops were ruined.

Summarizing,

• Give your roses a six-week potassium feast to harden up their canes for winter.
• Use at least 3 inches of wood chips in your beds, year-round, and more around your roses in the fall.
• Mound with good compost, including lots of coffee grounds.
• Tie up your roses in bundles and cut them back to 12-18 inches when they stop blooming.
• Cover them with half-filled leaf bags after the ground has frozen.
• Keep your roses frozen until spring comes over your window sill!

Let me know if you have any questions.  I would love to hear from readers in the cold zones of Europe, especially in Siberia (where my Volga-Deutsch father was born in 1902).

Please comment in the space below or send an e-mail to:  jack@falkerinvestments.com .

Jack Falker

September 2013