This is Utah State University Extension horticulturist Taun Beddes, based in Juab and Utah counties. Here are some simple tips to help your roses thrive along the Wasatch Front.
Covering the base of your roses with soil or mulch is a great idea. This simple step protects plants from subzero temperatures that don't happen every year, but can still cause serious damage when they do. In mountain valleys, subzero temperatures are much more common, so it's best to always cover the base of your roses, especially hybrid tea, floribunda, and grandiflora types.
To cover the base of your roses, apply about eight to 12 inches of high-quality mulch or shredded leaves around the base of the plant, paying special attention to the graft union. That is the swollen area on the stem near the soil line — that's the most vulnerable part of the rose.
Another item that is not often considered is actually tying your roses. Upright growing roses like grandiflora, floribunda, and hybrid tea benefit from this — or at least being loosely bundled to prevent branches from breaking under heavy snow load.
Throughout the growing season, and especially in the fall, keep an eye on your roses. Remove any dead or diseased canes as soon as you spot them and lightly trim taller canes to reduce snow damage. However, besides this light trimming, avoid heavy pruning and fertilizing roses in the fall.
Doing these things delays dormancy and makes the roses more at risk to winter damage. Wait to fertilize and do your heavy pruning from mid-March to early April, once the dangers of subzero temperatures are gone.
Thanks to Alisha Wilkins from USU Extension marketing for her contributions.