Saturday, November 10, 2012

More About Voles and Castor Oil

I just finished putting about 130 gallons of mixed castor oil and water around my roses and elsewhere in the beds, where voles might burrow their way through the wood chips and mulch.  If you missed my blog post about voles and the damage they inflict on roses during the winter, check it out right here:

As I began mixing the castor oil (which I got at Wal-Mart @ $2.65 for a six ounce bottle), I was frustrated at how it wouldn't mix with the cold rain water from my cistern.  I put one 30 gallon batch around the roses and it was clinging to everything; my gloves, the can I mixed it in, and the sprinkling cans I was using to pour it around the roses.  Then the lights went on.  I had forgotten to put the liquid detergent in the mixing can @one teaspoon per gallon!  As soon as I did that, the castor oil dissolved perfectly and the job became much easier.

So, here again is the formula for putting castor oil around your roses:  Use one or two teaspoons of castor oil and one teaspoon of dishwashing detergent per gallon of water.  Pour (or pump) the mixture around every rose so that it can soak into the dirt or mulch a couple of inches.  I probably put around half a gallon around each rose (or a little more) and then I pour it around between the plants and around the edges of the beds, i.e. anywhere that these little chewing monsters might burrow in the wood chips and mulch.

Castor oil is cheap, so I use more rather then less of it (i.e. two teaspoons per gallon rather than one).  Note: Ten ounces of castor oil gives you approximately two teaspoons per gallon mixed in a 30 gallon trash container.

If you haven't read the article  from New Hampshire Hostas, about using castor oil to control voles, be sure to take a look at it: .  The mixture formula is on their website as well.

This is prime time to put down castor oil.  As the ground freezes, the voles start burrowing around the beds to find the tastiest food supply for the winter: your roses!

So, don't make same the mistake I did and forget to put the liquid soap in your castor oil mixture. And good vole hunting!

Monday, November 5, 2012

The Big Coverup

Well, here in Minnesota and the northern tier of states, it's high time to be in the midst of covering our roses.  Mind you, it's not time to be finished yet, but the process should be ongoing, with an end goal in sight.

As those of you who have read my blog posts for the last few months 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 my 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.  See my August blog "No Tipping Please":  .  As you will see in that article, my thinking has also been influenced by the fact that we have experienced climate change in the garden.  (If you are doubtful of my conclusion, see also my blog post "Climate Change in the Rose Garden":

Before going any further, let's take a look at exactly what we are trying to accomplish by winter-protecting our roses.  Here in the upper-midwest, where the ground freezes solid in winter, it stands to reason that the roses freeze too.  In Minnesota, the ground freezes from several inches to several feet deep, depending on how much snow-cover insulation we get.  Obviously then, tipped roses are going to freeze just as solid as those that are left intact in the ground to go naturally dormant.  So, even though we can't stop the roses from freezing, we can try to stop them from repeatedly freezing and thawing, and that is what any method of winter protection is all about in the Upper Midwest, i.e. to keep the roses frozen until Spring.

Now there is clearly a line of demarcation where this changes, which is what makes this subject kind of confusing, depending on where you live.  In USDA Zone 6, where I was raised, and points south, the ground really doesn't consistently freeze for the whole winter, so the objective in these warmer areas would be to insulate the roses to keep them from freezing in the first place or, if you have a very cold period where they do freeze, to keep them frozen until it warms up.  Actually, I think the method I recommend, i.e. permanent wood-chip mulch, plus compost and leaves in the winter, works well in any cold climate, whether the roses consistently freeze or not.  It's just a question of how aggressively you protect.

All of my beds have at least three inches of permanent wood mulch on them.  I pull back the wood chips around the plants in the spring and summer, as I add organic fertilizer (Bob's Mix) and coffee grounds.  Then, in October, I push the wood mulch back around the plants and, for the plants that are zone 5 hardy, or more sensitive, I add several shovels of compost from my mulch pile, which is last year's shredded oak leaves and lots of Starbucks coffee grounds.  When the roses begin to go into dormancy in late October or early November, I tie them into a bundle at about the 18 inch level, using baler twine.  Finally, when the ground first freezes, which around here is usually in late November or early December, I shear off the tops of the plants with my hedge clipper, right at the 18 inch point, where they are tied.  Then I surround the plants with leaves, either by creating a cylinder of short fencing full of leaves, or by pushing a leaf bag with its bottom slit open down over the bundled plants.  I like the leaf bag method (which I learned from a Chicago-land rosarian) because it allows you to reverse the process in the spring without leaving excess leaves in the beds.  The bags can then be emptied into my mulch pile or into my bin for compost pickup (which in my case goes out to the mulch pile at the University of Minnesota Landscape Arboretum).

By the way, the reason for waiting until the ground freezes to put leaves around your roses, is that you run the risk of providing a habitat for voles if you put them on earlier.  See my post on voles:

Again, for those who have been reading my blog, you know that I have also been hardening off my roses with six successive weeks of liquid potassium applications (see: .)

 So, when I finish my "Big Coverup" I am quite sure that I have done more than enough to protect my roses from the Minnesota winter.  Because I am convinced that the Twin Cities area has moved solidly into zone 5, I also leave several of my zone 5 hardy plants (i.e. "Earth Song") with only the wood mulch covering on them each year.  While they die back closer to the ground, they recover very quickly in the spring and do just as well as the plants that were more aggressively covered.  I'll be doing that again this year and will report my results in the spring.

Let me know if you have any questions, or if you have any ideas about the "Big Coverup" that you would like me to publish.  I would particularly like to hear from readers in northern Europe and Russia, as to how you winter-protect your roses.  Send an e-mail to:  .

Here are a couple of pictures of the current state of the "Big Coverup" in my beds.  Note that the roses have been mulched and tied, but not yet cut back: