Green thumbs up: Final preparations for winterizing gardens

Temperatures tumbled over the weekend to their lowest levels this season as the Full Cold Moon appropriately glowed overhead. Also known as the Full Long Nights Moon, this second designation seems especially fitting, offering dual meanings, as the nights seem particularly long this month plus the December full moon spends more time above the horizon opposite a low sun. With the warmest fall season on record and the second warmest month of November, I suppose it was time for a reality check, although temperatures are expected to moderate again during the coming week.

As much as I welcome a return to above average temperatures, these fluctuations pose a serious hazard to shallow-rooted plants and late season transplants. Alternate freezing and thawing of the soil often cause these plants to heave out of the ground which may prove fatal if roots become desiccated or exposed to extended cold. Survey your gardens during the warmth of the day throughout the winter and firmly press plants that may have lifted out of the soil back into the earth. I keep a bag of bark mulch in my garage during the winter to surround the crown of uprooted plants, which provides additional protection. Applications of winter mulches are still on hold until the ground freezes solid.

Warm days followed by evenings below freezing can also adversely affect young or thin-barked trees, particularly those located in open areas or in southwesterly facing exposures. During the warmth of the day, the trunk of the tree, both its bark and inner core, expand in response to the heat of the sun. When the temperature drops dramatically at night, the thin outer bark rapidly shrinks, while the dense inner core cools down more slowly causing the bark to split and peel. The bark of a tree is analogous to our own skin. If the outer layer is damaged, the vital inner trunk becomes susceptible to infestations by insects and diseases. The use of tree wraps during the winter months can greatly reduce this damage. Local nurseries usually stock these protective wraps that breathe and expand as temperatures fluctuate in addition to protecting the trunks from destructive rodents near their bases. Keep grass short around tree trunks and remove leaves and debris until the ground freezes; be sure to remove this protection each spring.

Roses need special attention in order to survive our typically open winters. Protection of the bud union, especially the fist-shaped grafts of hybrid teas, is crucial for their survival during the coming months. This knob should have been planted about 2 inches below the surface but nursery pots are rarely deep enough to cover the graft and most of us are inclined to plant the rose bushes at the same level as they were grown in their container. To protect this critical growth point, a mound of fresh soil or well-draining compost should be applied to the base of the plant at this time of year. This cone-shaped mound should be 6 to 12 inches high and completely cover the crown. Use soil from a vegetable garden, compost pile, or bagged commercial products rather than pulling soil together from around the base of your roses as you risk exposing their shallow roots making them more susceptible to the cold. Apply a layer of mulch to the mound once the ground freezes solid. Many gardeners have embraced the beauty and ease of the new, low-maintenance cultivars like the ‘Knockout’ roses, but even these bushes should receive some winter protection during their first winter season. In exposed open areas, a cylinder of wire mesh or a burlap barrier can be placed around these shrubs and subsequently filled with oak leaves or pine needles.