By James Romer
Horticulturalist
Iowa State University Extension
Dear Dr. Grow-It-All;
Fall has typically been a busy time of the year for me. Knocking on doors, putting signs in yards, creating uplifting ads for radio or TV and asking for people’s vote has kept me from fall chores around the house. After the recent election, I suddenly find myself with more time on my hands. My new opponent, Old Man Winter, is ready to strike with a negative campaign of snow and bone-chilling winds. I’ve neglected protecting my roses and strawberries like I should and I don’t want him to win. I know that I’m the best candidate for the job of saving my constituents, I mean my plants. Dr. Grow-It-All, with your help we could be a winning team. Thanks for your support and I approve this letter.
Runnin’ in Redfield
Dear Runnin’;
The votes are in and there is still time to beat Old Man Winter. Yes, hybrid tea, grandiflora and floribunda roses should be protected in the fall. Exposure to cold winter temperatures can severely injure and sometimes kill unprotected plants. Prepare roses for winter after the plants have been hardened by several nights of temperatures in the lower twenties. Gardeners in northern Iowa can usually prepare their roses for winter in early November. Individuals in central and southern parts of the state should wait until mid and late November respectively.
Begin by removing leaves and other debris from around each plant. Then loosely tie the canes together to prevent strong winds from whipping and possibly damaging the rose canes. Next, cover the bottom 10 to 12 inches of the rose canes with soil. For additional protection, place 6 to 12 inches of clean straw over the mound of soil. The straw can be held in place with chicken wire fencing.
Remove the protective materials, untie the canes and prune out the dead wood in late March or early April. Prune out dead wood using hand pruners or lopping shears. Deadwood is brown, while live wood is green. When pruning roses, make the cuts one inch below the dead areas. Make the pruning cuts about a quarter inch above healthy, outward facing buds. Fall pruning is not recommended.
To answer the second part of your question, strawberry plants need mulch as protection against winter injury. If plants are not protected, low winter temperatures may kill the flower buds or damage the plant’s roots and crowns. Alternate freezing and thawing of the soil during winter may heave unmulched plants out of the ground. Apply mulch after the plants have been hardened by cool fall temperatures, but before temperatures drop below 20 degrees F. At temperatures below 15 degrees F, strawberry fruit buds are damaged. With each 5 degree F drop in temperature, the damage is more severe. At minus10 degrees to minus 12 degrees F and without winter protection of some type, severe losses may occur. Crowns may rot if mulch is applied before growth stops. In northern Iowa, strawberry plantings are normally mulched in late October or early November. Gardeners in central and southern portions of the state should mulch their strawberry plantings in mid-November and late November respectively.
Clean soybean straw, weed-free oat straw or chopped cornstalks are suitable mulching materials. Do not mulch with tree leaves as they can mat down and smother the plants. The ideal amount of settled mulch is 2 to 4 inches for winter protection (approximately 4 inches of soybean straw and 3 inches of clean oat straw).
Leave winter mulch in place until plants show sign of growth in spring. No harm will result even if many of the plants show one or two small yellow leaves. Delaying mulch removal prevents most frost heaving and may delay early blooming, thus reducing susceptibility to spring frosts. Remove just enough of the mulch so that the plant can grow through.
Examine the plants under the mulch every few days after there has been a week or so of warm temperatures in the spring. Place all of the mulch in the center of the aisles when 25 percent of the plants are showing signs of new growth. The mulch can be raked back lightly over the plants during bloom period if there is threat of a light late season frost. Following these techniques may give you of a long tenure of success with your roses and strawberries for future elections, rather years to come.
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