Winter Protection for Roses

Winter Protection for Roses

Part of Ep. 304 Early Winter Garden Care

Help your roses survive Wisconsin winter with an advice from Bill Radler, rose breeder and former director of Boerner Botanical Gardens.

Premiere date: Sep 30, 1995

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
We've talked a lot about getting gardens ready for next spring. Let's not forget about the plants that are already in the ground. Some of them are going to need winter protection. We're at Boerner Botanical Gardens and I'm with the retired director and rose breeder, Bill Radler. Bill, roses come to mind right away. Some of these need protection. What kinds?

Bill:
Well, most of your modern roses need protection, hybrid teas, grandifloras, floribundas, miniatures. There's few exceptions like the roses in Canada that have been bred for hardiness. Some of the modern shrub roses are hardier, also. But for the most part, everyday roses, they do need winter protection.

Shelley:
Well then, what's the most important thing we do to help them survive a Wisconsin winter?

Bill:
Well, the most important thing is when you plant the rose bush. And here I've de-potted a rose and it shows the graft union. This graft union needs to be insulated from the effects of winter by being planted deeply into the ground. So, I would recommend about two inches above the graft union is where the soil level should eventually be.

Shelley:
Now that's a lot deeper than I imaged. I think most of mine are about here.

Bill:
If you have it at soil level, you might get by. But if it's above, I would recommend transplanting for sure this fall.

Shelley:
So, this deep. Is it too late then? I mean, you said this fall. Can I transplant even up until the ground is frozen?

Bill:
As long as the ground isn't frozen, you can transplant.

Shelley:
OK, so we've got our roses correctly planted. What's the next step?

Bill:
Well, there's many winterizing methods that can be used. I think the styrofoam rose cone method is perhaps the best and easiest for the average person. I prefer the double styrofoam cone method.

Shelley:
Well, let's look at how we do that.

Bill:
Well, first of all, you need to tie up your rose into a compact cylinder, as is shown here. And, the ties are made low on the plant because we're going to be cutting the plant off. But, let me first tell you, the rose grows into dormancy because of the shorter days and the cooler temperatures. And, we're talking about-- you want to start the tying up process while the temperature is warm and comfortable for you to be in the garden.

Shelley:
And, more likely to be out there, then.

Bill:
Right, mid-October until mid-November is a good time. The week after Thanksgiving, the temperatures are really going to start getting cold and then we want to cut the rose bush back. And, I've done here--I've cut the top of this rose bush.

Shelley:
You're taking that much.

Bill:
You can see there's a large amount. You want it to fit within the rose cone. So, when you tie up, you gotta make sure that you have a secure tie low on the plant.

Shelley:
Now if I-- this just seems so drastic. Can't I leave it a little longer and let the stems actually touch the sides of the cone?

Bill:
Those stems won't make it through the winter if they touch the sides or the top.

Shelley:
OK, so I kill it that way. We cut it this far and it's happy that way.

Bill:
Right, you're going to be cutting it back that short in the spring, anyway, ten inches or less. So, you can prepare your rose cones ahead of time by putting holes, four holes, in the top to allow for ventilation. And so, this is the week after Thanksgiving when the temperature gets 25 or lower at night. And, you put this over the rose cone. Actually, the roses can take to zero to ten degrees when they're fully dormant. You can't see the dormancy by looking at the plant. They all look like they're green and alive until frost really kills the leaves.

Shelley:
So, pay attention to the temps in your area.

Bill:
L And, the time of the year, the week after Thanksgiving. And, after you've put the styrofoam cone on, you want to put soil or mulch around the base to help seal it. Then weigh the cone down with a brick so the wind doesn't blow it away.

Shelley:
That's it, then, we're done?

Bill:
Uh, not completely. I mentioned we have a double cone. This is a non-ventilated cone and you put that on after the temperatures are below zero.

Shelley:
So, the really cold part of the winter.

Bill:
Right, the really cold part.

Shelley:
Why can't I just take off the cone that's got the holes in it and just replace it with this cone when it gets really cold?

Bill:
You can try it, but it's going to be frozen to the ground. That won't be possible.

Shelley:
OK, so we just take the brick off and slide it right down?

Bill:
Put the cone on.

Shelley:
Brick back.

Bill:
Brick back. And then, wait for warm weather. In the spring of the year, if we get unusually warm weather, you don't want heat to build up in the cone because that will cause the rose to go out of dormancy and then be injured by the temperatures that it would normally not be.

Shelley:
So are you talking about, I think the January thaws, things like that?

Bill:
That's a possibility, but if leaving the top one on is going to hold the cold down in the cone, you want that to happen. In the spring of the year, this changes because we get warmer days and the frost is starting to come out of the ground. You want that frost to stay there. So, sometimes ventilating the cone in the spring of the year would be more judicious.

Shelley:
OK, so if the ground is still frozen, we're almost better off leaving the cone on to keep the cold in then.

Bill:
Right.

Shelley:
And then, it comes off permanently in April?

Bill:
Yes, middle of April, not sooner. By the end of April, you definitely want to make sure you have the cone off.

Shelley:
And then, hopefully, we'll have a lovely rose coming up.

Bill:
You bet'cha.

Shelley:
Right, thanks, Bill. The way to start out is with a good, hardy variety of rose. Boerner Botanical Garden publishes an annual list of outstanding varieties.

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