By Mike Fuss
In the challenge of protecting roses for a New England winter, the best strategy is to start with a healthy bush. This is a bush that has been properly planted, fertilized, watered, and protected from pests and diseases. How to do these are topics for other discussions, so we shall begin our winter protection plans assuming you have bushes that have been growing reasonably well through the season, and you now face the long winter with the hope that your roses will be alive in the spring.
The purpose of winter protection is to help roses to become dormant and to insure that once the roses are cold they remain cold. In this way, they remain dormant until spring and are protected against damaging cycles of freezing and thawing.
Most roses are propagated by the graft of a bud onto a rootstock. This graft, or bud union, which is at or just below ground level, is the most important part of the plant to protect. For if the bud union dies, then the bush will be useless and you will end up shovel pruning it.
To provide extra protection, when you plant a bush insure that the bud union is three inches below ground level.
Although the autumn is the time most people begin to think actively about winter protection, preparations should begin in August and continue through the fall. Winter preparations begin by withholding nitrogen based fertilizers after July, so as not to encourage new basal growth, canes which would not harden off before winter. As cooler weather approaches, there is less need for water and regular watering should be less frequent. In fact, rainfall alone can be relied upon, unless there is an unusually dry period. When picking blooms in the fall, take shorter stems and when blooms have gone by, instead of deadheading, remove only the petals. This will allow hips to form and will help the plant begin dormancy.
Active winter protection begins after two or three hard frosts have occurred, but before the ground has frozen solid. The usual time in our area is Thanksgiving. A number of techniques can be used. I shall discuss bush roses first and then minis and climbers.
The most common winter protection is a combination of soil around the base of the plant and a covering of oak leaves. Bring a load of soil in from another area of the yard (such as the vegetable garden or annual garden) and hill it up around the base of the rose to a height of at least eight inches (twelve inches is better). A collar makes the task easier. Just place a collar around the bush and fill the collar. Collars also help keep the soil from being washed away by winter rains. Collars can be made from wood (nail three sides together, slide it around the bush, then tack on the fourth side), roofing paper (cut to size and stapled together), or several layers of newspaper folded and stapled together. Collars can also be purchased. A word of caution about the “hilling with soil” technique: do not use soil taken from right around the bush. If you do, you will expose roots to much colder temperatures and will likely cause winter damage. If you choose not to use collars, the soil mound will need protection from winter erosion. Once the ground is frozen, cover the mound with oak leaves or evergreen boughs. Un-hilling in the spring can usually begin by the second week in April. One could also use compost or bark mulch. The advantage here is that compost and bark mulch don’t need to be removed from the garden in spring. Just spread it out in the rose bed
A second technique which is quite successful is the use of Rose Kones. You may want to use a Rose Kone for a plant that is very difficult to get through the winter since these Kones have become expensive, but they work very well. They are made of Styrofoam, look like upside-down waste baskets, and stand about 20 inches high. The first step is to cut the rose canes down so that the Kone will fit over the bush. Then strip the leaves from the bush. Next, tie the canes together with butcher’s twine and slip the Kone over to check the fit.
The Rose Kone is a one-piece unit and if you use it as is, the rose will develop mildew because of a lack of ventilation. So it is necessary to punch three or four one-inch diameter holes in the sides of the Kone about two inches from the top. In addition, in order to prevent overheating during the fall and spring, cut a large hole in the top of the Kone. When it comes time to cover the top, use a piece of plywood since it is difficult to match the cut piece with its hole. Some Kones come with preformed removable tops so look for these to save yourself some cutting work.
Now, once you have prepared the rose, place the cone over the bush and secure it with a few shovels of mulch around the base and a stone or two bricks on top. Nothing is needed inside the Kone. Once the mulch freezes, the Kones will be immovable. The top of the Kone should be left open until the weather is consistently cold. I usually put on the tops on New Year’s Day – a great way to start the year.
Now the roses are set until spring. Around the second week in March temperatures have risen enough so that the tops can be removed to provide extra ventilation and prevent excessive heating. Usually by the second week in April the Kones can be taken off.
Miniature roses are much easier to protect than their larger cousins. They only require having some oak leaves around them for the winter. If you have some of the larger varieties of minis, prune them down to less than one foot. It is easiest to confine the oak leaves with 24” chicken wire. Place 1” x 3” wood stakes around the mini bed and staple the wire to them. Next, add oak leaves and work them down and around the bushes, making sure they are covered on all sides. The leaves should be about 18” deep. When spring arrives, remove the leaves early to allow the garden to thaw. The leaves hold moisture and will lead to rotting conditions if not removed by the end of March. Be sure to use oak leaves since other leaves will mat down and not provide protection.
Climbers, in my opinion, are the most difficult to get through a winter. In order to be able to bloom, the main canes must make it through undamaged. Wrapping the canes in burlap or other porous fabric will help protect them from the drying effect of the wind. Tying the wrapped canes to a trellis or stake will keep them from whipping around in the wind. Hilling the base of the climber will protect the bud union, just as for a bush rose. Perhaps the best advantage you can give your climbers is to plant them in an area that is protected from severe winter winds.
Now, just a few final thoughts.
Clean up leaves and other debris from the garden before piling on soil or other winter protection. It will make opening up the garden in the spring so much easier
Use only oak leaves. Other types of leaves will mat down and do more harm than good.
If your roses have long canes, and you don’t want to prune them back until spring, tie the canes to a stake to keep them from being wind-blown and loosening the roots.
Spray your roses one last time with a fungicide before covering them up for the winter. Some rosarians feel this just provides a psychological boost for the rose grower; however, if you feel it will help, don’t hesitate.
The final phase of winter protection is its removal from the garden. This can begin any time from the end of March on, depending on the weather.