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Did Big Freeze Damage Our ‘Hardy’ Plants?

The extended freeze is making Eugene area rhododendrons, azaleas and other plants looking sad and shriveled. Will they survive?

 “The cold weather causes the water in the leaves to evaporate, and with the ground frozen, no water enters the plant and/or leaves,” says Ross Penhallegon of the OSU Lane County Extension. “The leaves then start to wilt and droop. The longer the cold (below 25 degrees) weather, the more damage or water loss to the leaves.”

But Penhallegon says that even after two weeks, assuming the temperature returns to above freezing, the leaves will replace the water. “Same with the roots,” he says. 

What saves the native trees and shrubs is that most are in the dormant stage this time of year and can withstand below-zero temps, he says. Non-native plants might not do as well in this weather, along with potted plants that are not protected.

EW garden columnist and consultant Rachel Foster says some rhody varieties are hardier than others when it comes to cold weather. “Some will undoubtedly suffer,” she says, “and a few will die. Some will be just fine depending on parentage and where the parents came from.” She says she’s more worried about her fig tree than her rhodies.

Another factor is the snow, which provides some insulation of tree and shrub roots. “Back in 1996, we lost roses, rhodies, azaleas, pampus grass and many California type plants, Penhallegon says. That cold spell did not include much snow. He recommends covering root zones with mulch or compost before cold weather comes.