Preparing outdoor flowers for winter

A Guilford gardener received a potted blooming azalea for a gift last spring and planted it out shortly afterwards. The shrub apparently took hold nicely and now sports a healthy crop of dark green leaves. The question is whether to give it winter protection or not.

Sad to say, most potted azaleas are intended to remain so. Evergreen azaleas, while they make excellent florist crops and not overly difficult house plants, are not hardythis far north. I recommend digging up the plant before the middle of November, potting it in a peaty soil and bringing it indoors for winter. Bright sunlight and a cool room would suit a housebound azalea best in winter.

A related question which pops up again and again is how best to protect roses, especially hybrid teas, against winter kill.

I telephoned Dr. Paul Cappiello, University of Maine professor of horticulture, for his advice on this — I have to say it — thorny issue. His response contained some novel approaches.

The first step, of course, is to prune back severely, leaving 8-16 inches of cane with a few good buds. Traditionally, the next step has been to mound earth up around the cane and cover with either an insulating mulch or a foam rose cone. Whatever success comes from this method, it has the severe disadvantage that the cane remains above ground and is thus subject to our extremely low air temperatures in January and February.

Alternative number one is to simply dig up the rose (after pruning) roots and all, and overwinter it in a very cool cellar or even a spare refrigerator. Pack the entire plant in barely moist peat or green sphagnum and wrap loosely in paper or plastic. The object is to dry the rose down but not dessicate it to the point of no return. In spring, the cane should be replanted as soon as the ground can be worked.

Alternative number two is something called the Minnesota Tip. Developed at the Minnesota Landscape Arboretum in Central Minnesota, the technique couldn’t be easier. After pruning, dig an 8-inch trench on one side of the rose and sever all its roots on the same side. Next, insert the spade on the opposite side of the rose to sever as many roots as necessary to allow the entire plant to be tipped into the trench and buried. Perhaps only 20 percent of the roots will be left intact, but this is enough to get the vigorous plant going again next spring.

By burying roses below ground level, you can hold them in just a few degrees below freezing, even if the ground freezes solid. For extra insurance, the Arboretum recommends a thick layer of insulating mulch (oat straw, pine needles, bagged leaves) over the trenched plants. Of course a marker is helpful to relocate roses in spring. Come April, the roses are unearthed, righted and treated with the TLC they deserve.

Michael Zuck of Bangor is a horticulturist and the NEWS garden columnist. Send inquiries to him at 2106 Essex St., Bangor, Maine 04401.