Removing Winter Mulch

By: Kelly Feehan, Extension Educator

Release: Week of March 27, 2023

As temperatures warm in spring, plants covered with mulch for winter should be checked for new growth. If there is none, leave mulch in place as long as possible. It is important not to remove winter mulch too early or to cut the tops of herbaceous perennials off too soon.

While winter mulch and perennial tops provide some protection against cold temperatures, other key benefits they provide are protecting plant tissues from winter drying and slowing spring growth. 

On warm, windy days in early spring moisture can be lost from exposed plant tissue. This is at a time when roots are not yet taking up water from cold soils. Lost moisture is not replaced by dormant roots and this is when most winter injury occurs. Leaving mulch in place as long as possible decreases tissue drying.

With erratic Nebraska temperatures, above average temperatures in early spring may cause plants to break dormancy. New growth may even begin on some plants. Leaving mulch or dead stems in place to delay growth can help protect plants from spring freezes. 

 It is important to check mulched plants, like strawberries, on a regular basis for signs of new growth once temperatures begin to warm. If there is no sign of growth, leave mulch in place and recheck covered plants on a regular basis.

Once growth begins, it is important to remove mulch as plants need light exposure or the foliage will turn yellow and die. Leaving mulch in place after plants break dormancy can also lead to crown rots.

When removing mulch, rake it to the side of plants but keep it nearby. When freezing temperatures are in the forecast, rake mulch back over plants to protect them overnight. Remove it again the next day when temperatures are warm enough.

 The roots of herbaceous perennials survive from year to year but the tops, stems and foliage, die back to the crown each winter. This dead material needs to be removed annually. Examples of herbaceous plants are asparagus, ornamental grasses and plants like peony, black-eyed Susan, milkweed and coneflower.

Don’t be in a hurry to cut these dead tops back in spring. Just like mulch, they protect plant tissues from dessication injury as well as from starting to grow too early and then being exposed to freeze damage.

While mulch needs to be removed once plants begin growth, there is not as big of a hurry to remove the dead tops of perennials. With many perennials, it is recommended to leave 8 to 10 inches of the tops to help conserve pollinators, like solitary bees, that may be overwintering inside the stems.

To protect plant tissues and pollinators, help delay growth, and catch snow for added moisture if we receive anymore, wait until new growth on these plants is a few inches tall, and leave 8 inches of dead stems.

The exception is asparagus. While it is helpful to leave the old ferns of asparagus in place as long as possible, they are best removed just before new growth begins or as soon as spears begin to peak through the soil. This will prevent spear tips being damaged when cutting off asparagus tops.

On another note, a majority of questions received by Extension relate to shade and evergreen tree problems. If you have a question, or want to be more informed about current issues to protect your trees, attend my upcoming Tree Issues talk on April 12 from 7:00 to 8:30 pm at the Extension office in Columbus, 2715 13th street. For information, call 402-563-4901 or go to platte.unl.edu and download the Lawn, Tree, Garden & Landscape class pamphlet.