The days are getting shorter and mornings a bit cooler. It must be getting close to fall and time to think about getting your roses ready for winter. We love our roses in northern Nevada. But unless you have shrub roses, which need little extra care except mulch and winter watering, they do need to be prepared ahead of time for the cold, drying winds of winter.
Winterizing roses is all about preventing new growth at the end of the season, and providing insulation for existing growth before the first frost. New growth is especially vulnerable to frost damage, and such damage exposes your plants to insects and disease. You can prevent new growth by refraining from fertilizing and backing off a bit on water a few weeks before the first frost date, about the first of October in the Reno area.
During years when we get significant snow cover that lasts, your roses may do fine without protection. But these days you can’t rely on an insulating snow cover unless you live further up the mountain. To provide protection, start by watering your roses thoroughly to a soil depth of about 18 inches. Next, clean around your roses and dispose of leaves and brush that could harbor disease organisms. Then prune the canes of your hybrid teas, floribundas, grandifloras and climbers to a height of about 3 to 4 feet. Some people like to tie the canes together with string, but that is not absolutely necessary.
You do want to protect the vulnerable bud union at the base of the rose plant from freezing. The bud union is the point where the rose plant was grafted to a rootstock. The bud union looks like a deformity in the stem at the base of the plant. Protect it from sunscald and temperature fluctuations by covering loosely with an 8- to 12-inch mound of fresh soil or aged compost. Mulching over the top of your mounded soil and around the base of shrub roses is also helpful. Mulch may consist of a 3- to 4-inch layer of straw or leaves. This provides extra protection by keeping moisture in the root zone and protecting surface roots from temperature extremes.
Protect your climbing roses by untying them from their trellis and wrapping the canes with burlap. The burlap and canes can be held together loosely with string. If the canes are flexible, you can lay them on the ground, stake them in place and cover them with soil or mulch. Roses in containers also need special care because their roots are above the insulating ground and are more exposed to fluctuating temperatures. Bury the container in the ground or move it to a protected spot, against a wall where it will be protected from wind or intense midday sun. Multiple containers can be grouped together for extra protection. Again, a layer of mulch on the surface of the soil will further protect the roots.
Finally, continue to deep water your roses throughout the winter – every two or three weeks. Water during the warmest part of the day, or when temperatures are above freezing and the ground is not frozen. This will provide your roses with enough moisture to keep the living tissues from drying during the winter.
For more information about gardening in our high-desert climate, visit www.growyourownnevada.com. Heidi Kratsch is the Area Horticulture Specialist with the University of Nevada Cooperative Extension. She can be reached at 775-784-4848 or firstname.lastname@example.org.