The days are getting shorter, there is an ever present nip in the air, and leaves crackle under your feet as you walk to the mailbox - the outdoor gardening season is coming to a close. The frigid temperatures always seem to invade too soon. For wasn't it just yesterday we were enjoying bright zinnia bouquets, garden ripe tomatoes, and the enticing scent of rose blossoms? In order to reap the same rewards from the garden next year, it is necessary to take some protective steps this fall. Roses are often at the top of gardener's list for winter protection.
While there are some native and old fashion shrub roses that can stand up to old man winter, most of the modern roses (such as hybrid tea, floribunda, and grandiflora) need a helping hand to live through Iowa's coldest season. Often times it's not the low temperatures that damage rose bushes, rather rapid temperature changes and repeated freezing and thawing do the most damage. If you are uncertain as to the necessity of protecting your rose for the winter, go ahead and take steps to winterize it. Winterizing cannot hurt the plant when done properly.
First of all, a healthy rose bush is much more likely to make it through the winter than a weak, pest-infested bush. Control insects and diseases during the growing season. Also, gardeners should not fertilize rose bushes after July 31. Succulent late season growth will be too tender to handle winter conditions and could lead to winter injury. Stop deadheading roses in late summer. The development of rose hips promotes hardening of plants in preparation for winter.
Remove diseased leaf debris around the base of the rose plant. This should reduce disease problems next year. Tie the canes together with twine to prevent whipping of the canes during strong winds.
A protective mound of soil around the base of a rose is essential for Iowa winters. If you have limited time to prepare your roses for winter, this is the one step you don't want to skip. Protect the lower portion of the rose bush with an eight to twelve inch mound of well-drained soil. The soil used to make the mound should be brought to the rose bush from another location; do not remove soil from the rose's root zone to make a mound. Roses should be covered with soil a couple of weeks before the ground freezes - mid to late November is often recommended.
For added protection a layer of mulch can be placed over the mound of soil. Bark, wood chips, or straw can be used. Hold the mulch in place with evergreen bows or chicken wire fencing.
Remove the soil and mulch in the spring, usually early April in Iowa. With Iowa's variable weather, there is always a chance a spring cold spell could strike. During an extended period of freezing temperatures, recover the rose bush temporarily.
Climbing roses are more of a challenge in terms of winter protection. The entire plant must be covered with soil. Begin by removing the rose from its trellis or climbing structure. Then carefully bend the canes to the ground. Gently pin the rose down and cover the canes with several inches of soil and a layer of mulch. Climbing roses can be uncovered with all other roses in the spring.
A little work in the rose bed this fall will be rewarded with vigorous bushes next spring.
This article originally appeared in the October 8, 1999 issue, p. 126.