Winter Shrub Protection: Black Plastic, Cardboard, Pine Straw, and Windbreaks

Thoughts on protecting shrubs from winter cold:

BLACK PLASTIC

Counterintuitively, black plastic is better than clear. Object: trap soil heat around trunk and limbs. Plastic is windproof and effective IF anchored to ground on all sides with stones or heavy limbs.

Problem with clear plastic: on cold sunny days, "greenhouse effect" raises temperatures underneath. If too warm, plant sends sap to buds; when temperatures drop that night, buds damage easily. Black plastic reflects sunlight; temperatures rise minimally. Better than clear plastic, blankets, or quilts.

Grab helper, razor knife, black plastic sheeting; measure pieces for large plants like gardenias, camellias, hydrangeas.

CARDBOARD BOXES

Many small plants fit under cardboard boxes. Bend flaps out, put rocks on top to anchor. Container plantings on decks are good candidates.

PINE STRAW

Spring bulb leaves (tulips, daffodils) unaffected by normal cold. Light pine straw sprinkling makes bulb bed attractive. Pansies and ornamental cabbage shrug off regular winter cold. But if strong winds bring low teens, light pine straw blanket protects leaves from drying.

OLD BEDSHEETS

Not recommended for covering plants, but excellent for windbreaks around newly planted evergreen shrubs. If you installed prize rhododendron or camellia last fall, make a windscreen. Drive four wooden stakes, staple sheets. Sheet top a few inches higher than plant. White windbreaks may not endear you to neighbors, but could mean live plants this spring.

UNFROZEN WATER HOSE

Biggest cause of winter plant damage: lack of water. Evergreens (magnolias, etc.) protect themselves by wilting leaves at night. Next day leaves fill out. But if ground dry or frozen, roots can't supply water. If gusty winds or long cold approaching, soak ground around evergreens.

MORE INFORMATION:
Cold Protection of Ornamental Plants
Cold Protection in the Landscape