How to Winterize Roses (and When to Start, by Zone)

About this table: Each row is summarized from the extension sources named in it; the sections below quote each one and link to it.

• Grafted modern roses need it most. Iowa State University Extension: “Most hybrid tea, grandiflora, floribunda, and other modern roses require protection during the winter months. Low temperatures and rapid temperature changes in winter can severely injure and sometimes kill unprotected modern roses.” The weak point is the graft union: “This graft union is particularly sensitive to cold temperatures and requires protection over the winter months.”
• Why the graft matters. Penn State Extension: “If the graft union is compromised, the part of the plant above that graft union will die.” University of Missouri IPM adds that in severe winters “the root system of unprotected plants might be the only part that survives”, and the suckers that grow back will not match the named rose.
• Hardy roses need little. Iowa State: “Most old garden roses possess excellent cold hardiness and don’t require winter protection.” University of Minnesota Extension says hardy shrub roses “rarely need elaborate winter protection; their genetics do the work.”
• Match the rose to your zone. Penn State: “A rose cultivar that has been specially bred to be hardy in Zone 4 will need little to no added protection when growing in a Zone 7b garden.” Own-root roses “may also need protection, depending on their hardiness compared with the garden’s hardiness zone.”
• The goal is steady cold, not warmth. UNH Extension: the main goal is “to keep the plant, especially the crown and lower portion of the canes, uniformly cold throughout the coldest winter months.” “Cold damage occurs due to plant tissues alternating between freezing and thawing”. Illinois Extension: “Wet and cold is far more damaging than dry and cold.”

• Let the rose slow down. Clemson HGIC: “Stop fertilizing your roses six weeks before your expected first frost date.” Illinois: “stop dead-heading or cutting flowers after October 1 and allow the plant to form hips.”
• Water before the ground freezes. Penn State Extension says to “water thoroughly late in the season, after the first frost, but before the ground freezes.” Clemson: as it gets cold, “reduce the amount of water, but do not allow roses to completely dry out.”
• Clean up. Iowa State University Extension: “Removal of diseased plant debris will help reduce disease problems next season.” Penn State: “Dispose of and do not compost diseased leaves and plant parts.”
• Tie the canes. Iowa State says to “Loosely tie the canes together with twine to make working around the plants easier and prevent the canes from being whipped by strong winds.”

Should you cut back roses in fall? Only lightly. UNH Extension: “Heavy fall pruning of bush roses could mean loss of the entire plant in the event of a severe winter.” Leaving 18 to 24 inches of healthy cane under the mulch, it says, gives you new growth and healthy canes in spring. It does advise cutting “extremely long stems back to prevent their whipping about in winter winds”, and sums it up: “A good rule for tea roses is to cut less in the fall and more heavily in the spring.” How far down differs by source: University of Minnesota Extension cuts hybrid teas “back to 24-30 inches after hard frosts to prevent wind rock”; Clemson says “To prevent wind damage on large bushes, cut the canes back to 3 feet.” For other perennials, see which perennials to cut back in fall.

Mounding soil or compost over the base of the plant is the standard method for grafted roses. It keeps the graft union and the lower canes at a steady temperature.

• Build the mound. Iowa State University Extension: “Cover the bottom 10 to 12 inches of the rose canes with soil.” University of Missouri IPM: “form a mound about 10 to 12 inches high and 18 inches wide at the base of the plant, covering the stem and bud union.”
• Bring the soil in. Illinois Extension: “Soil that is used to “hill-up” plants should be brought in from outside the rose garden. Scraping up soil from around the plant can cause root injury and lessen the plant’s chance for survival.” Penn State suggests “a 12-inch-deep mound of well-draining compost, potting mix, clean soil, or aged manure”.
• Mulch on top once it freezes. Illinois: “After the soil mound has frozen, the mound can be covered with evergreen boughs, hardwood leaves, or straw to help insulate and keep the soil frozen.” Iowa State: “Typically 1 to 2 feet of material loosely packed is sufficient.”
• Keep it in place. Iowa State: “A small amount of soil placed over the straw or leaves should hold these materials in place. Alternatively, wire fencing can hold the loose mulch material in place.” Missouri: “Additional mulch may need to be added during the course of the winter should the original application settle.”
• Or use a collar. Illinois: “An 18-inch-high circle of hardware cloth or chicken wire is placed around the plant. The collar is filled with soil, allowed to freeze and then mulched with straw.” Its benefit: “it holds the soil in place all winter”.

Iowa State University Extension says “Skip the styrofoam cones.” Fitting a rose inside takes heavy pruning, and “These cones can also get very warm on a sunny winter day.” NDSU Extension adds that “The cone traps moisture that can lead to rotting.”

If you do use cones, Illinois Extension says to wait as you would for other methods, and “Cut four to five 1-inch holes around the top and bottom of the cone.” It also advises mounding “soil around the crown of the plant before putting the cone in place” and weighting the cone “with a brick or stone to keep it from blowing away.”

• Climbers in a sheltered spot: UNH Extension says to “secure canes to their support and prune off long ends. Next, wrap the canes in burlap, straw, or evergreen boughs and tie with twine. Mound 10”-12” of soil around the base of the plant.”
• Climbers in cold or open spots: UNH says “the best way to protect a climbing rose is to shield the entire plant with earth.” Iowa State University Extension describes it for climbers that aren’t reliably hardy: “remove the rose from its trellis or climbing structure. 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.”
• Hardy climbers: University of Minnesota Extension: “Skip heavy pruning until spring. Tie canes securely against wind. Mulch the base as you would a shrub rose.”
• Tree (standard) roses: Penn State: their “graft union for rose standards may be more than three feet above the ground”, so “The stem, bud union, and several inches of the canes emerging from the graft will need to be protected.” One option is wrapping the cut-back head and fencing the stem with leaves or straw; the other is to lay the whole plant down. Iowa State lays it down in early to mid-November and covers “the partially exposed root ball, trunk, and all the stems with 10 to 12 inches of soil.”

The Minnesota Tip (coldest zones). University of Minnesota Extension: “after several hard frosts but before the ground freezes, lay the plant into a shallow trench and cover with soil.” NDSU Extension explains the steps: tie the canes, dig a trench next to the plant, loosen the roots on the far side with a spading fork and tip the rose in. “If done correctly, only the roots will bend.” Then “After the soil has frozen, cover with another foot of leaves or straw.”

Where winters are milder, the job is lighter. N.C. Cooperative Extension, Guilford County: “For zone 7 roses, cover the graft union with about 5-6” of pine, mushroom compost, or hardwood mulch.” The base of tender rose bushes can also be mounded with 10 to 12 inches of soil, which it calls particularly important for grafted roses. It prunes “only to 36” high” in late fall and says “Heavy pruning occurs in February.” Clemson HGIC recommends “A 3-inch mulch of pine straw, leaves, pine bark, or wood chips” and “Leave some space clear of mulch against the stem.” University of Missouri IPM says winterizing shrub roses such as “‘Knock Out’ is not necessary at our latitude.”

• Why pots need it. Iowa State University Extension: “Potting soil temperatures in containers left above ground are likely to get extremely cold, damaging or destroying the roots of the rose.”
• Easiest option. Penn State Extension: “Moving the entire container into an unheated garage or shed is the easiest option.” Otherwise wrap the container and several inches above the rim in big-bubble bubble wrap, or fence it and fill with leaves or straw.
• Bury the pot. Penn State says smaller pots can go in the ground “once the plant is dormant and before the ground freezes.” Iowa State does this “in late autumn before the ground freezes but after the plant has gone dormant (mid to late November)”, then covers the bottom 6 to 8 inches of the canes with soil. Clemson HGIC: “Roses grown in containers need to be put in the ground, container and all, in a protected area of the yard.”

More on containers: when to bring potted plants inside.

Penn State Extension: when winter lows “are not forecasted to dip below 20°F”, start removing the mound. “This may take several attempts as lower layers may still be frozen and need to thaw before removal.” Iowa State removes everything “after the ground thaws in the spring - typically sometime between mid-March and early April in Iowa.” Save the main pruning for spring: UNH’s rule is to cut less in fall and more in spring.