If you garden in a colder zone, you need to offer your roses at least some degree of protection in the winter. Most winter damage to roses is caused by frost heave (damage to the roots) or is the result of sun scald and drying winter winds (damage to the canes). Because even the hardiest of roses can succumb to unpredictable winter weather, it's best to choose a good method of protection before the cold weather arrives.
Give Them a Healthy Send-Off
Healthy roses have a better chance of surviving winter than roses weakened by disease, drought, or nutritional deficiencies. To prepare your roses for the onset of cooler temperatures, stop fertilizing and deadheading them starting in the late summer or early fall. As temperatures drop, start to cut back on watering, but make sure to never let them dry out completely. Before covering plants, rake away any nearby debris to remove any plant material that could potentially harbor pests or diseases over winter. Prune the canes back to a size that accommodates your chosen method of protection, while leaving as many of the remaining flowers intact as possible. The flowers will form rose hips - signaling the plant that it's time to go dormant.
Wait for the Big Freeze
One of the trickiest parts of putting your roses to bed for winter is knowing when to do it. Covering plants too early can be as damaging as not covering them at all. As a general rule, it's safest to wait until you have a week of consistently freezing temperatures and a hard frost has caused most of the leaves to fall.
Protection By Rose Type
These are general guidelines. Exactly how much winter protection your roses will need depends on the severity of your climate, the specific type of roses that you are growing, and how healthy the plants are going into winter.
Climbing or Rambling Roses: Cover the base of the plants with a mound of soil. To leave the stems on their existing supports, wrap them in burlap packed with straw and secure them with twine. In severe winter zones, remove the stems from their supports, carefully bend them over and stake them to the ground, and cover them with at 6 inches of mulch.
Container Roses: When temperatures drop below freezing, move container roses into an unheated garage or outbuilding until the weather warms up again in the spring. Check them occasionally throughout the winter to make sure the soil in the container doesn't completely dry out, but don't give them any fertilizer. Another method is to sink the plant, container and all, into the ground outdoors. Surround the exposed part of the plant with a collar or cage and fill it with straw or leaves.
Hybrid Teas and Floribundas: Apply a final dust or dormant spray before covering plants. Cover the crown of the plant with at least 6 inches of soil, then cover the entire plant and soil mound with an additional 6-12 inches of hay or straw. In harsh climates these rose types may need to be buried.
Shrubs and Old Fashioned Garden Roses: In all but the coldest zones, most shrub roses and old fashioned garden roses require little or no winter protection. In colder zones, mound the plants with straw or hay as you would with more tender roses.
Tree Roses: In all but the mildest climates, remove the support stake and lay the trunk flat on the ground. If the trunk cannot be bent without causing damage, use The Minnesota Tip method (below) to lift one side of the root ball out of the ground so the trunk can lay flat. Cover the entire plant with soil (top, trunk, and exposed roots) and mulch with an additional several inches of straw. Tree roses growing in containers can be moved into an unheated garage or outbuilding until spring.
Mulching Heavy (minimal protection)
In moderate climates, frost heave is seldom a problem and minimal protection may be all that is necessary. Mulch heavily, 3-4 inches deep, around the base of the bush. Pile on leaves or evergreen boughs to protect canes from drying winter winds and sun damage.
Rose Cones (minimal to moderate protection)
Another method of winter protection for roses is the use of polystyrene rose cones. This method is not nearly as popular as it used to be, partly due to the fact that the cones are not well suited for use on large rose bushes, and if you don't use them correctly, you can run into all kinds of problems. If you use this method, make sure you don't cover your plants until they go dormant. Also, to prevent the inside of the cone from heating up on warm winter days (and causing the roses to break dormancy), cut four to five 1-inch ventilation holes around the outside. These holes will help keep air inside the cone moving and prevent it from overheating. Mound soil around the base and use rocks or landscape staples to keep the cones from blowing away.
Hill, Cage, and Cover (moderate to maximum protection)
Mound up soil around the canes to a depth of 6-10 inches (deeper = greater protection). Create a container around your bush using fencing or chicken wire and fill it up with leaves, wood chips, or straw to protect the canes from sun and wind damage. Commercially-made "rose collars" are also available at nurseries, garden centers, and online. It's best to purchase them ahead of time, as they can be difficult to find once freezing weather rolls around.
The Minnesota Tip (maximum protection)
Tie the canes together. Dig a trench out starting at the base of the bush (it should be as long as the plant is tall). Carefully pull the soil away from just below the bud union (graft) and using a spading fork, gently loosen the soil around the roots. When the roots are loose, tip the bush over into the trench and cover it with 2 to 3 inches of soil (you may need to bring in additional soil from outside of your garden to accomplish this. After the ground has frozen, cover the tipped bush with an additional 12 - 24 inches of leaves or straw. Watering the leaves/straw will help form an insulating capsule of ice to help keep the bush dormant. Use chicken wire or fencing to keep the leaves/straw from blowing away.
One question that comes up for many gardeners this time of year, is how to prepare their roses for winter. The harsh winter weather found colder zones (zones 6 and below) can easily claim the lives of hybrid tea roses, floribunda and grandiflora roses, unless they are offered at least some level of winter protection. There are several ways to prepare your roses for winter and which method works best continues to cause heated debates among rosarians. In my opinion, it doesn't matter which method you choose, just as long as it carries your roses through until next spring.
How Freezing Temperatures Affect Roses
Understanding how roses can be damaged by winter weather can help you decide which level of protection your roses will need. In general, the colder winter, the more protection they need.
Common Winter Injuries:
Roots drying out. This usually happen as a result of the plants being heaved out of the ground due to the ground constantly thawing and freezing.
Direct injuries sustained to the roots and canes as a result of extremely cold temperatures.
Temperature swings (sunny days and cold nights) resulting in cracks or splits in the stems.
Injuries and breakage sustained by animals, snow or ice.
By mid-August you should stop fertilizing. Don't do anymore pruning now either, or you will only encourage new growth. Clean up and remove any fallen leaf debris to prevent insects and disease organisms from taking refuge over winter. Keep up with your watering schedule until the ground starts to freeze.
Methods of Protection
Once your garden sees a few hard frosts, it's time to add some winter protection. Don't add mulch or compost any sooner, or you'll run the risk of interfering with the plant's natural ability to ready itself for winter. If necessary, cut back the canes to 18-24 inches to make them easier to handle, and bundle (tie) them to prevent "rocking" damage from winter winds.
Mounding or "Hilling": Use fresh soil (or compost, bark, vermiculite, peat moss, saw dust, etc.) to create a mound of loosely layered mulch around the base of each bush. The mulch should be at least 10-12 inches deep. You don't have to cover the entire plant, but make sure the base of the bush is well insulated against the cold.
Gardeners in the coldest zones (6 and below) will want to take this a step further and cover the entire plant with mulch. You can do this quite easily by adding a collar around the bush made from chicken wire, hardware cloth or a tomato cage. Wrap the collar with cardboard, bubble wrap or tarp, fill it up with fresh straw and cover the top to prevent snow or rain from collecting inside. Keep the straw loose and the mulch porous to encourage air circulation and avoid smothering the roots and crown. This method usually provides enough protection for roses grown in zones 7 and 8.
Rose Cones: Another method is to add 10 to 12 inches of loose mulch around the base of the rose bush and cover it using a commercially available rose cone. These are usually made from Styrofoam and will need to be secured by some type of weight (rock or brick) to keep them from blowing away. If you're covering extremely tender roses, cut of the top of the cone and add straw for extra protection. It's also best to poke a few small holes in the sides of the cone to allow for some airflow.
Tipping: Here in Minnesota, many rosarians use a method we call the Minnesota Tip. The first step is to dig a trench. Start the digging away from the bush and work your way towards it. The trench needs to be long enough and wide enough to accommodate the entire rose bush.
Now using a spading fork, carefully pull the soil away from the area between the bud union and the main branching of the root system. You want to loosen the soil around the roots until you can bend or "tip" the bush completely into the trench. Hold the bush down into the trench and cover it with 2 or 3 inches of soil. On top of this, add 18 inches of loose leaves or straw. Around April 1st, gradually uncover the roses as the weather continues to warm up. By mid April, the roses can be lifted back into their upright positions and the canes syringed with water to prevent them from drying out.
Protecting Climbers: To protect climbing roses, remove them from their supports, bundle the canes, lay them on the ground and cover them with 6 to 10 inches of soil and mulch. Try to avoid cracking or splitting the stems when bending them.
Winter Rose Care for Zones 9 through 11
Roses grown in these zones don't need protection from cold temperatures, but they are subject to fungal diseases from wet winter weather. Give your bushes a light feeding now and plan on pruning them after they bloom next month.
Choose Roses Hardy to Your Zone
The best way to avoid winter injuries is to start with a healthy rose bush. Vigorous plants that are free from insects and disease stand the best chance of surviving winter weather. Most importantly, choose a variety that is hardy to your zone. This isn't always as easy as it sounds, because most modern roses are usually hybrids and they are not always tested thoroughly for hardiness. It's a great idea to solicit advice from local gardeners who have successfully grown locally purchased roses under "real-life" local growing conditions. Ask them how they prepare their roses for winter and who sells the best quality roses in your area.