By Carl Wilson, Colorado State University, Horticulture
Have you noticed that your roses have stayed green through Thanksgiving? The prolonged warm weather this fall has provided an extended growing time for many plants. It also has delayed cooling of soils, altering the timing for applying winter mulch. Winter mulch is applied after soils have cooled. The purpose is to delay early spring growth that typically is killed by further cold weather. Winter mulches also help to retain moisture essential to winter root survival. In December, when night temperatures consistently drop to 20 degrees Fahrenheit, mound soil over the rose crown. The soil should be eight to 10 inches deep. Other mulches that can be used include pine needles, boughs, leaves or sawdust. Leave the mulch on until all danger of a hard frost has passed in spring.
What about other perennial flowers?
Mulch will protect perennials from winter drying and frost heaving. Frost heaving cracks the soil and exposes roots to drying cold and injury. Mulch also is benenficial to use over spring bulbs because it delays spring growth until weathre is warmer and more settled. The ideal mulch doesn't compact easily, allows air and water movement into and out of the soil, breaks down slowly and is weed-free. Many plant wastes can be recycled including wood chips and leaves.
Photograph courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010