April's Ag Advice by April Borders There is nothing more beautiful in a flower garden than roses. But there is nothing more frustrating than trying to get them through our winters. Roses must be protected not only against low winter temperatures, but also against fluctuating temperatures and winter winds. The most important thing you can do to protect your roses is to keep them healthy during the growing season. The healthier they are going into winter the better their chances for survival.
Most rose bushes are not completely hardy in our region and they need to be protected from cold with insulators such as soil, mulch or cones. When using soil as an insulator, mound the soil around the base of the canes after the first hard freeze while the soil can still be worked. Bring soil from another part of the garden to do this, as you do not want to injure the roots by removing soil near them. Tie all the canes together to keep them from being wind blown and loosening the soil around the base of the bush. You may have to cut back the canes to reduce wind whipping, but do not cut the canes to the soil level as they might winter kill. After tying the canes together, mound the soil 8 to 10 inches high around the canes.
After the ground has been frozen in late fall, usually around Thanksgiving, pile hay, straw, leaves or similar material over the mounded canes. Hold the material in place with a thin layer of additional soil. This helps keep the soil temperature constant. It is important that you wait until the ground is completely frozen. This will help reduce root injury.
If you use a commercial Styrofoam cone, it is recommended that the cone have an open top. If it doesn't have an open top make sure that you puncture several 1-inch holes around the top of the cone for air circulation. If you don't provide ventilation you are creating a mini greenhouse for the rose on warm days and this could actually cause more damage than good. Place the cones on only after the roses are completely dormant, usually after Thanksgiving, or after two hard freezes.
Tie the canes together, slip your cone over the rose bush, then fill the open-top cone with a mulch of dry vermiculite, leaves, straw, perlite or similar materials. Cut the tops of the canes even with the top of the cone. Check the plant occasionally during the winter for evidence of mice, wind or other damage, if possible.
Remove covering materials in the spring as soon as the danger of hard frost has passed, but before new growth appears. If new growth has started, the plant may need protection in case of frost. Carefully remove the soil that you mounded. You don't want to break off any shoots which have started to grow.
With proper care and planning, your roses can survive our harsh winter months. For more information, contact the Extension Office at 677-7111.