I had always been impressed and amazed by my friend, Eileen Rosen, who grows Damask and Moss roses in her garden. After reading the article she wrote for this publication, I have a new respect for her efforts that produce huge plants covered in blooms in our formidable Prairie climate. In the last few years with the changing climate resulting in milder, more fluctuating winter temperatures and a lack of adequate snow cover may be the new norm. Therefore there is increasing importance to use appropriate techniques to protect roses, tender or otherwise, from killing back over the winter.
I have brought together some basic information to overwinter roses on the Prairies. All of this is gathered from various websites like The Canadian Rose Society, various university horticultural pages, rose outlets, and consultation with the guest editor.
General suggestions to assist your rose to survive winter are: Buy roses that are tolerant to your zone when possible. (If you fall in love with and MUST have a rose that is on the edge or outside your zone, be very sure to pay attention to the later sections of this article.) Be sure you have generally healthy plants that have been planted well and have good drainage. Before the snow flies, cut back the longer canes on upright type roses to prevent them from whipping around and causing damage by the wind (Climbers and Ramblers are different). Do not begin adding insulation to the area around the rose too early, as the ground needs to be colder or have started to freeze. Mulching too soon will attract rodents or other pests to this warm shelter. They may even snack on the rose canes.
Roses that are budded or grafted stand a greater chance of damage or total destruction due to severe cold than those on their own roots. The more tender the rose, the more attention to winter protection; and if in doubt.... protect it. Look for 'own root' when possible and those noted to tolerate the coldest temperatures in your area based on the hardiness zone maps. Shrub roses like the Explorer, Parkland, Buck or Bailey roses stand a better chance in colder zones and usually require less protection. Needless to say, they do fine in Zone 4+. Take advantage of the growing number of attractive, hardy "own root" roses that are currently offered. I wish, however, that commercial outlets would carry more of the lovely, older Prairie-developed roses by breeders such as Skinner or Wright.
To prepare your rose for dormancy and winter, stop fertilizing early enough so growth slows down. No fertilizer should be applied after mid August. Next, stop dead-heading or cutting flowers after October 1 or sooner depending on your area and allow the plant to form hips. Around this time you should cut back the longer branches to about 70-75 cm (28-30 in) to prevent them from whipping around and to allow for any wrapping or cone coverage for the on-coming winter. Remember, the goal is just to create a reasonable sized plant for winter with the real pruning taking place in the spring. Prior to any covering, remove any foliage or other debris that might harbour disease for the next season (including on the ground around it).
The goal of winter protection is to ensure the plant is uniformly cold and frozen all winter, and prevent the damaging effects of alternate freezing and thawing. It is critical that your roses are dormant for winter. The freeze-thaw cycles during the winter often cause more damage than consistent cold temperatures. Usually it is late fall or early spring when this is a greater problem due to the lack of snow protection for your roses and sever fluctuations in temperature. You should also consider location and the exposure to freeze--thaw when you plant your rose. For example, the south wall of my house is not a good place to plant more tender roses due to the early spring melt. I have to be out there every day moving snow from the shady areas to try and offer more coverage to these shrubs. Only the hardiest roses have survived well in this location. (it: 'Morden Blush', 'Pink Grootendorst' and 'William Baffin.')
The final step for winter protection, especially for roses that have been grafted, is to "hill-up." This doesn't need to be complicated or involve purchasing special materials. To "hill-up", use loose, well-drained soil/compost mix around and over the plant to a depth of about 25-30 cm (10-12 in). Soil that is used to "hill-up" plants is best brought in from outside the rose garden. Scraping up soil from around the plant can cause root injury and lessen the plant's chance for survival. Again, drainage is important. A rose that is planted in poorly drained soil will suffer and often not survive the winter whereas that same rose, planted in a well" drained site, will flourish. Wet and cold inflicts far more damage than dry and cold. Some people use rose collars or cones to keep the soil from washing away. The soil mound should be allowed to freeze. It can then be covered with evergreen boughs, hardwood leaves, or straw to help insulate and keep the soil frozen. Remove the hill-mounds in early spring, when buds are swelling on deciduous trees and shrubs.
A popular method of winter protection for tender roses is the use of Styrofoam rose cones. To correctly use cones, don't cover the plants too early, applying the same timing guidelines that are used for other methods of covering roses. Cones outer layer of evergreen must be well-ventilated to prevent heat build-up on the inside during sunny winter days. Ensure that there are four to five 1-inch holes around the top and bottom of the cone to aid in ventilation and keep the air inside the cone from heating up and causing the rose to break dormancy. It is also advisable to mound soil around the crown of the plant before putting the cone in place. For extremely tender varieties, some rose growers recommend cutting off the top of the cone and stuffing it with straw for added protection/insulation. It is also a good idea to weigh down the cone with a brick or stone to keep it from blowing away.
The Calgary rosarian, the late Don Heimbecker, reported great success with this eco-friendly method for tender roses: "First, cut each rose down to about 20 cm (8 in) then mound 15 cm (6 in) of peat moss around the base of each bush. Then cover the rose plant with 30 cm (12 in) of straw or dry leaves. Finally, using old carpet, tarps or burlap, cover the rose beds to keep the leaves or straw dry and in place and to insulate the plants."
Climbing roses like 'Joseph's Coat', "Red Fountain' and 'Roberta Bondar' are generally grown by only the most adventurous prairie rosarian, but with proper care they can be spectacular in full bloom. First, remove the canes from the trellis or support and carefully bend them to the ground. Then, secure the canes to the ground with pegs or stakes and completely bury them with several inches of soil. The Explorer climbers like 'John Cabot' or 'William Baffin' that grow as Pillar roses on the Prairies only need good ground coverage, as they will flower on new wood if the canes are winter killed to any extent.
Tree or standard roses are produced by bud-grafting the desired rose variety onto a tall stem. Since the cold-sensitive bud union may be .6-1 m (2-3 ft) above the ground, tree roses are extremely vulnerable to winter injury or death. Tree roses are best suited to areas with mild winter climates or those who are prepared to dig in the entire plant. First, start with loosening up the roots; lay it down, and then the entire plant should be covered in the same manner as noted above for climbing roses. Recently, there have been Tree roses that are 'own root' standards available at the larger nurseries here in Manitoba. However, friends who have tried these report mixed success.
In closing, I recommend that you share experiences with other rose devotees in your area regarding the different types of roses best suited for your area, what works and what doesn't. Enjoy.
To Valerie, retirement has meant an opportunity to have a full time commitment to gardening. Valerie is currently President of the East Kildonan Garden Club and active in several other Societies in Manitoba.
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|Date:||Jan 1, 2008|
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