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Winterizing roses

Wed, 10/24/2018 - 12:00 am

Green Side Up

Except for some of the more tender rose varieties such as floribunda and hybrid teas, it is not normally necessary to devote a lot of time and effort to protecting roses in the winter. Mr. Lincoln, Tropicana and Chrysler Imperial are among the hardiest hybrid teas. However, this year both the national weather service, NOAA and The Old Farmer’s Almanac are predicting a “bone chilling” winter because of the El Niño effect. If our weather of about ten days ago is any indication, they may be right. Of course, The Old Farmer’s Almanac only claims about 80 percent accuracy, and one forecaster stated that anything more than a 10-day look into the future is a “crap shoot.” Drawing on my Boy Scout days, it is always good to “be prepared,” especially when it comes to Texas weather.

Even if the winter turns out to be mild, our roses will benefit from a little extra TLC. Of course, the

healthier the plant before winter the better it will endure any cold weather. A couple of major concerns

when preparing roses for winter is provide adequate air circulation to prevent diseases from taking hold as to not to promote new growth and promote dormancy by stopping fertilization six to eight weeks before the expected first frost. For us, this is the first week in November, according to the Almanac. This reduces the chance of new foliage being developed that will be subject to freezing and the resultant die back. If you cannot control yourself and absolutely must fertilize, use a high phosphorus content (middle NPK number) formula with a very low nitrogen content (the first number). This will stimulate root growth which is a good thing when preparing for winter dormancy. Late pruning will also stimulate growth and weaken the plant’s energy reserves. If you have not already done so, stop deadheading roses shortly after the middle of September and allow hips to form. These are the reddish seed pods of roses. Although not backed up by research, intuitively it seems that the formation of seed pods should slow down growth. This is true for other plants so it stands to reason that roses will respond in the same way.

In order to prevent diseases and fungus from overwintering, clean the beds of leaves and other debris.

Spray the canes with dormant oil to kill insects that attempt to overwinter on the plants. Dormant oil is

highly refined oil that is applied to plants during their dormancy and is available at garden centers (a

homemade version can be made with two tablespoons of ultrafine canola oil plus one tablespoon of

baking soda in a gallon of water.) Dormant oils can damage non-dormant plants. Dormant oils differ

from horticultural oils in that horticulture oils can be applied anytime of the year, even to non-dormant

plants. If you make your own anti-fungal baking soda solution (one third cup of baking soda to a gallon of water), simply add the two together and spray once.

The crown of the plant (the point at which the grafted portion attaches to the root stock) should be

protected with a layer of leaves. Do not use rose leaves since these may harbor insects or diseases. This leaf mulch is generally adequate in our area. If the temperature is expected to be below 15 degrees Fahrenheit, the crown needs to be protected by covering it with at least six inches of soil and then adding a leaf mulch layer. It may be necessary to wrap the plants in burlap in addition to mulching under very cold conditions. This can easily be done by utilizing those tomato cages left from the summer garden. Bind the canes together so that they will fit inside the cage. Carefully slide the cages onto the bound canes which have been trimmed to a manageable length (trim only when the plants are in maximum dormancy). Fill the cage with leaves and wrap the cage with burlap or other non-plastic, breathable material. Leave the top of the cage open for ventilation. The tops of the canes may be killed back but they are going to be pruned off in the spring anyway.

Climbing roses may need to have their long canes tied together to avoid being thrashed by the wind. In extreme winters they may need to be wrapped and carefully laid down on the ground and covered with mulch. Completely burying the canes will protect them further. Our drying winds should be guarded against when protecting roses.