When to Trim Roses in Colorado

Colorado's dry climate and harsh winters are hard on roses, but with proper plant selection and care, you can have a thriving rose garden. Prune roses in late spring, as new green growth emerges, so you can clearly see what plant material is dead or damaged. Discard pruned plant material in the trash to avoid the spread of disease.

Prune roses back in mid-to-late spring when tulips are blooming and the base of the rose plants are turning green. Remove all dead and diseased branches until you see green wood. Most years you'll prune back to about 12 inches above the ground. If the winter was especially severe, prune back to ground level. Occasionally, a plant may not survive and requires replacement.

Cut weak, diseased branches or those that rub against each other back to the ground. Cut all other branches back to new wood. Make cuts 1/8 inch above an outward facing bud, if possible, cutting the branch at a 45-degree angle so water can drain off. Paint the newly exposed tips with clear fingernail polish to prevent cane borers from boring into the tender wood.

Apply a 2 to 3-inch layer of wood chip or bark mulch around the base of the plant to stabilize soil temperatures and prevent heaving. Heaving occurs when repeated freeze and thaw cycles cause the soil to push plants out of the ground. Colorado winters are notoriously unpredictable and heaving is often a problem. Cover roses with a 6 to 12-inch mound of loose soil after the first hard freeze to further protect roses. Remove the soil slowly, beginning in April as tender young shoots emerge.

Roses in Colorado need water, even in the winter. Water at least twice a month during from late fall to spring. Lay a hose on the ground near the rose plants and allow it to run on slow flow for at least 30 minutes. Water in the middle of the day when temperatures are above 45 degrees Fahrenheit, so the water absorbs into the ground. Water before an expected deep freeze, as well, since moisture protects the roots from serious damage.