In midautumn, it’s time to prepare all types of roses for winter’s worst

Garden questions arrive weekly by e-mail and snail mail and I try to reply promptly with the time left after class preps and grading. Readers wait, patiently for the most part. Often I feel that the answer to one gardener’s question would be useful to many of my readers. Such is the case with the following.

Winterizing climbing roses

Wende Pottle of Perry, just down the road from where I teach in Eastport, asked in a recent letter about winterizing her climbing rosebush. The answer starts with two assumptions. First, I assume that she has selected a truly hardy variety of climbing rose, one that can take the frigid winds of a Down East winter.

Second, I hope that she prepared her rose for winter by watering adequately in late autumn and not applying nitrogen after late summer. Both of these cultural measures ensure a stress-free plant tough enough to take what’s coming.

To winterize a climber, remove the canes from their support and lay them on the ground, burying them with 3 to 4 inches of soil covered with mulch. The soil should come from somewhere else in the garden, not from around the plant; removing the soil over the plant’s root system would result in winter kill of the roots.

This works well for climbers with canes flexible enough to bend down to the ground. If the canes are too stiff for this approach, you can leave them on the trellis, tie them together, and then wrap them in straw surrounded with a layer of burlap. In either case, the base of the climber should be covered with 10 inches of soil and then a layer of mulch.

Now is the time to winterize all roses, including hybrid teas, floribundas and grandifloras. Begin by cutting each plant back to about 24 inches and tying the tips together. Build a mound of soil over the center of the plant at least 12 inches high and as wide, then cover the mound with a mulch of composted leaves, straw or evergreen boughs.

An alternative approach is to construct a wire-mesh cylinder around each plant and fill it with all mulch instead of soil. Wood chips, sawdust or shredded bark work well in this method. The wire cylinder can then be wrapped in burlap for additional protection.

Winter protection should be left in place until all danger of freezing temperatures has passed.

Vines for shady sites

Two readers have asked recently about the best vines to grow in shady garden sites. Two possibilities come immediately to mind, Virginia creeper (Parthenocissus quinquifolia) and American bittersweet (Celastrus scandens).

Recommending woodbine are its fast growth rate and brilliant red fall foliage. The berries, also ornamental, ripen in late summer and are quickly eaten by birds, mice, skunks and chipmunks.

American bittersweet’s chief ornamental feature is its fruit display. The round, orange-yellow capsules open in autumn to surround scarlet-colored seedpods that remain on the plant well into winter and provide food for songbirds, game birds, and squirrels.

For successful bittersweet berry production, both male and female plants are required. One male will pollinate up to five females planted within 30 feet. Best fruit production occurs in full sun, although the vine itself will tolerate partial shade.

A word of caution: American bittersweet is related to the non-native invasive Oriental bittersweet (Celastrus orbiculatus), a vine that is displacing the native bittersweet in New England as it strangles and smothers native shrubs and trees. It is important to make this distinction, to plant only the native species.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to rmanley@ptc-me.net. Include name, address and telephone number.