How to winterize your roses

I will be leaving for a two-week vacation on Nov. 10 and was wondering if I should prune back my hybrid roses and cover them before I leave?

— Tyler Jackson, Crystal Lake

It is probably best to winterize your hybrid roses after you return from your vacation. Chicago Botanic Garden staff waits until there has been a hard freeze of around 18 degrees Fahrenheit or three nights in the low 20 degrees before beginning the winterizing process. Generally, this happens around Thanksgiving, with the work being completed in the first week of December, even if the temperature minimums have not been met. The roses are cut to about 18 inches to make it easier to mound them. It is best to clean up and remove foliage that might be infected with black spot disease before covering plants. The Garden uses well-aged horse manure to mound the roses. It is comprised primarily of sawdust from a stable, and approximately 15 inches of compost is mounded over the base of the plants. This is removed in early spring as temperatures begin to warm — typically in early April just as the roses are starting to leaf out. The Krasberg Rose Garden has been uncovered as early as late March in exceptionally early warm spring weather.

There is no need to take these special maintenance steps with landscape roses, which should be treated like other shrubs in your garden. Most home gardeners have landscape roses. These do not need to be cut back and mounded with compost. On the other hand, David Austin roses can benefit from some extra winter protection. Some examples of roses that do not require mounding in the fall are flower carpet roses, drift roses, knock out roses, meidland roses, rugosa roses, Fairy rose, Carefree Delight and Carefree Wonder. For the most part, just leave them alone for winter. Prune them to remove dead wood, and thin and shape the plants as needed this winter. It is OK to lightly prune them now if they need to be neatened up.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.