This winter season has been up and down like a clown on a pogo stick. Should you worry about how dips in the polar vortex and 50-degree temperature swings will affect your plants?
“If you have the right plants and you are taking care of them, most will be able to handle winter extremes,” said Sharon Yiesla, plant knowledge specialist in the Plant Clinic at The Morton Arboretum in Lisle. “The plants most likely to be damaged are evergreens that may dry out.”
For plants, drought and cold are winter’s major challenges. Cold has immediate physical effects: When the water in plants’ cells freezes, sharp-edged ice crystals slice open the cell walls so they can’t hold water. “That’s why your leftover annuals and vegetable plants go limp after the first freeze,” Yiesla said.
Plants that are truly winter-hardy — well adapted to survive cold temperatures — have a number of defenses against this freezing. Many simply abandon their tender and vulnerable parts such as leaves and stalks every autumn. Only protected parts — roots insulated within the surrounding soil, wood protected by bark, buds covered by bud scales, seeds with tough coats — will live through the winter. The tender green stems and leaves will be replaced in spring.
Some plant tissues that must survive winter cold, such as buds, undergo chemical changes in autumn to reduce the concentration of water in the liquid of their cells. “It’s a little like antifreeze,” Yiesla said.
Winter in cold regions is also a time of drought, as far as plants are concerned. Plants need water for almost all of their life functions, and water that is frozen to ice is not much use. “That’s another reason so many trees drop their leaves in fall,” she said. “When there’s no liquid water for photosynthesis, there’s not much point in keeping tens of thousands of little solar collectors fluttering on your branches.”
Most winter-hardy plants avoid these hazards by entering dormancy, a sleeplike state where not much happens until spring. Not much can hurt dormant plants.
The exceptions are evergreens that keep their leaves in winter, such as spruces, yews and boxwoods. Although they do slow down, evergreens never are entirely dormant. “They keep water in their tissues and their leaves will still photosynthesize when it’s warm enough,” she said.
Since evergreens contain water, they can dry out. “Cold air is dryer than warm air, so a bitter cold night can really suck moisture out of them,” Yiesla said.
There’s not much you can do about evergreens’ exposure to cold outdoor air, apart from watering them well in autumn. You won’t even see the damage until spring. But you can protect the plants’ roots down in the soil from their worst winter enemy: warmth.
“With our changeable weather, the biggest threat to many plants in January and February is a thaw,” Yiesla said. A brief spell of temperatures in the 50s or more may warm up the soil enough to trick plants into thinking spring is here, so they come out of dormancy. If they sprout or their buds open, that new growth will be killed by the next sudden drop in temperature.
To avoid that, keep the soil cool with insulation. Snow is an excellent insulator because it’s mostly air. But the Chicago area, with its volatile weather, rarely keeps a blanket of snow all winter.
“The most reliable insulation is mulch,” Yiesla said. “A layer of dead plant matter, whether it’s fallen leaves, purchased mulch, or compost, will help protect roots against those tricky thaws.”
[ad_1] [ British teenagers believe their generation will have a worse life than their parents, according to new research.Money, jobs...
[ad_1] [ Your report (Seeing same GP ‘improves patient health and cuts workload of doctors’, 23 February) is welcome yet...
[ad_1] [ At a recent wedding ceremony in Britain, guests gasped when it came time for the couple to exchange...
[ad_1] [ ALBION, Pa. -- ALBION, Pa. (AP) — “You are the Lighthouse in someone’s storm,” reads the message above...
[ad_1] [ As a young mother, I was haunted by the terror that one day a child of mine would...
[ad_1] [ Hundreds of newly established care providers have been granted licences by the Home Office to sponsor workers from...