K-State horticulture expert outlines steps to protect plants during colder months
November’s temperatures in much of Kansas have proven to be unseasonably warm, but rest assured, the colder days of winter are not far away.
For gardeners, that means giving attention to garden plants in order to protect them from the inevitable freeze.
Kansas State University horticulture expert Cynthia Domenghini shared tips for protecting two popular plants – roses and strawberries.
Winterizing roses
Most shrub roses are hardy through Kansas winters, but many hybrid teas and other modern varieties require protection, Domenghini said.
“It is important to winterize roses after several hard frosts have occurred, but before the ground freezes,” she said. “Winterizing too early keeps the stems warm and moist, which promotes the growth of mold. Winterizing too late risks damaging the sensitive graft union where the root stalk attaches to the above-ground growth.”
To prepare the plants for winter, clean up debris in the area surrounding the roses to prevent diseases from overwintering. Mound soil or compost 8-10 inches high around each rose plant. Domenghini said this is also a good time to bring in new soil – instead of soil around the roses – to avoid exposing and damaging the roots.
Once the ground has frozen, add a four-inch layer of straw, leaves, wood chips or other mulch over the mound, and cover with a layer of soil to hold it in place.
“This will help protect plants from the cold, but also prevent early budding during warm winter and early spring days,” Domenghini said. “As the mulch settles during winter, you may need to add more.”
Prune canes to 36 inches and remove weak or thin canes. Tie the remaining canes together loosely to keep them secure during windy weather. “If the canes are allowed to whip in the wind, it can cause damage to the crown and disturb the soil,” Domenghini said.
When the ground thaws next spring, remove the mulch and soil from the base of the plant to return the soil level to normal.
Winterizing strawberry plants
Mulch is necessary to protect strawberry plants from winter damage, regardless of whether they are young or established, Domenghini said.
“Sudden drops to freezing can kill fruit buds and injure roots and crowns,” she said. “When the soil freezes and thaws repeatedly, plants can be heaved out of the soil, exposing the roots.”
Domenghini recommends a three-inch layer of straw mulch for plants after they have been exposed to several frosts, but before the heavy freeze begins. In Kansas, this usually falls between Thanksgiving and Christmas.
More information on caring for strawberries is available online in a publication from the K-State Extension bookstore.
Domenghini and her colleagues in K-State’s Department of Horticulture and Natural Resources produce a weekly Horticulture Newsletter with tips for maintaining home landscapes and gardens.
Interested persons can subscribe to the newsletter, as well as send their garden and yard-related questions to [email protected], or contact your local K-State Extension office.
PHOTO: A closeup shot of a red rose covered with snow. (iStock │ #1437713351 – Wirestock)
