Because of climate change, extreme measures of winter protection, like the “Minnesota Tip”, in which roses are laid-over into trenches, in my opinion, seem to be a lot of unnecessary, back-breaking work for northern gardeners. In addition, this method (which I personally used for many years) has the additional disadvantage of disturbing the natural growth pattern of the plants and often, when the roses are raised, results in bud unions and roots being too close to the ground surface for good horticultural practices.
There are several good, protective alternatives, which are most common in zone 5 (and incidentally work just fine in zone 4, as well). All involve building up soil or mulch around the base of the plants and then applying leaf cover in some form, after the first hard freeze. It has always seemed to me that doing this was much better for the plants horticulturally than tipping them out of their normal growth pattern. Handling all the leaves in both the Fall and Spring is also a lot of work, but there is a method, commonly used in Chicagoland, that makes it a lot easier. Simply take a leaf bag, fill it about two-thirds full of leaves, tie it up, cut a slit in the bottom of the bag, and push it down over the rose plant, which has been cut back to about 18 inches and bound together with baling twine. This works even better if the leaves have been shredded before you put them in the bag. Incidentally, do not use the new (and very expensive) compostable bags because they will fall apart over the winter leaving you with a pile of leaves, along with pieces of the bag, around each plant in the Spring. The nice part of using the leaf bags is that you can simply roll them off the plants with the leaves still intact, dump them either in your mulch pile or yard-waste container and throw away the used bags. The leaves remaining around the plants can be worked into the soil, along with the residual mounding mulch, making a good natural fertilizer. Construction blankets can also be successfully used as an insulator, in lieu of leaves or leaf bags, but they present the added problem of having to store them somewhere for eight or nine months of the year.
Typically, with either method, the plants will be as well-protected and ready to prune, as they would be if they had been tipped; just a little shorter. The major difference will be that their roots have not been disturbed and can immediately begin growing toward the first Spring bloom.
Warmer winters have become the norm in other parts of the northern hemisphere, as well. For example, looking at the Arbor Day maps in my climate change article, Chicago has moved from zone 5 into zone 6, as well as much of the lower-peninsula of Michigan, where previously it had just been around the Detroit area. This means that much lighter winter cover, with just leaves or several inches of wood chips, may be in order for these areas. My advice would be, if in doubt, use the leaf bag method described above, but with less mounding necessary.
For those who are ready to accept my “No Tipping Please” thesis, it’s time to get busy right now. Your bud unions are either above or right at the ground surface and they need to be covered immediately to get ready for winter and the mounding process to come. My advice is to order in a load of mixed black dirt and sand to raise the level of soil around your plants. In the Twin Cities, The Dale Green Company (Burnsville) will deliver you an excellent mixture of black-dirt, sand and black-peat, which is the best rose-soil mixture I’ve ever used. You can have them add horse manure as a fourth element, but keep in mind that the manure will raise your soil pH, which is not advisable because your roses like a slightly acidic soil.
Once you have given your previously-tipped roses a nice new layer of dirt and sand, you will want to mound them further in the late Fall before putting leaves (or leaf bags) around them. If you don’t have a mulch pile started to use for mounding this year, order in extra dirt and sand to set aside and use this Fall. Next Spring you can use the leaves and surplus mulch/dirt you take off your roses to build a mulch pile to use for the next winter’s mounding; and then, as you can see, it just goes on from there, year-to-year.
As time and future winters go by, you will become more confident in the amount and type of cover needed each year. In any event, I’m pretty sure you will agree with my “No Tipping Please” thesis going forward.
E-mail me with any questions: firstname.lastname@example.org.