The gentle spring garden of May is slowly yielding to the vibrant red, blues, yellows and purples of the summer garden. Annuals like zinnias, marigolds, snapdragons and petunias, and perennials like lilies, peonies, phlox and irises will soon be coming into bloom. And then the most popular garden flower, roses.
We can grow roses in Minnesota. The floribunda and tea roses that are in full bloom in southern climates will not be in bloom here until the middle of June and these varieties of roses require a great deal of care and protection to survive our winters. The “Minnesota Tip” is one method of protecting tender rose bushes from our harsh zone 4 winters. It is the method developed in the middle of the last century by a long time member of the Minnesota Rose Society and used at the Arboretum. It involves digging a trench alongside the rose bush, loosening the soil around the roots and laying the rose bush down in the trench. The bush is then covered with soil and spends the winter protected beneath the soil. This process is usually completed by October 15 at the Arboretum and “rose lifting day” is six months later, around April 15. Thus our rose growing season is much shorter than in southern zones.
An excellent alternative for someone who would like to have roses, but is not up to the work involved in protecting them, are the hardy shrub roses. Shrub rose is a catch-all category for all roses that don’t fall into another category. Generally they are a shrubby plant with increased winter hardiness and improved disease resistance. Some are repeat bloomers and some bloom once in early summer. Being winter-hardy means that the roses will survive the winter without protection. They may suffer die-back to the snow line or even to the soil line, but they will send out new growth in the spring from the old wood or from the crown.
Some cultivars bud on new wood, which means they set their buds in the spring. These cultivars will have as many blooms as previous years even if they die back to the soil line. However, those cultivars that bud on old wood may suffer a reduction in blooms if they have serious die back to the snow or soil line. If you decide to plant a hardy shrub rose be sure you know which type of shrub you have. If you chose one that buds on old wood, you may want to protect it with mulch or cones to reduce the amount of die back.
Twentieth Century breeding efforts in Canada produced many shrub rose cultivars in the Explorer Series and the Parkland/Morden Series, which are hardy, vigorous bloomers in our climate. Besides being winter hardy, they are grown on their own roots and bud on new wood, so even if they die back to the ground in winter they will send up new growth from the crown in the spring, remain true to type and produce abundant blooms in the summer. William Baffin is a climbing rose from the Canadian Explorer series that can grow 7 to 9 feet in one season. Other varieties from Canada include the Morden Blush, Morden Centennial and Morden Fireglow. In the last half of the 20th Century repeat blooming cultivars were bred at Iowa State University by Dr. Buck. These cultivars do well in the southern half of the state and include Applejack, Country Dancer, Prairie Flower and Prairie Harvest. Newer zone 4 repeat bloomers and black spot tolerant cultivars include Candy Oh!, Vivid Red!, Carefree Delight and Pink Gnome.
Shrub roses will grow vigorously if they are planted in well-drained soil in a location where they get at least six hours of direct sunlight daily. They need at least 1” of water per week, either from rain or the garden hose. Always water at ground level, to minimize the amount of moisture on the leaves and thus prevent the development of black spot. Putting organic mulch such as compost, or wood chips around the base of the shrub can help maintain the moisture in the soil as well as add nutrients and control weeds. Your shrubs will also benefit from fertilizer every two to three weeks, but discontinue fertilizing after August 1 to allow the plant to harden off for the winter.
Hardy shrub roses are becoming very popular in our zone and further north so you should be able to find a nice selection at most area garden centers. You can plant them anytime during the growing season but the sooner the better. If you purchase and plant one soon you should be able to enjoy the flowers this year – the prime time for roses in Minnesota is June, but many will continue blooming into July. Enjoy.
– Don’t grumble that roses have thorns… Be thankful that thorns have roses. – Rudyard Kipling