Nature is waking up too early this year.
At the Minnesota Landscape Arboretum in Chaska, some spring bulbs were blooming on Valentine's Day — months off schedule. And then it started snowing.
"Snowdrops should not be blooming until early April. We are seeing some things that we should not be seeing yet," said Erin Buchholz, the arboretum's plant health specialist. "It's just been an incredibly unusual winter. I'm hoping that our temperatures just kind of stabilize and gently go up from here."
Our unseasonably warm weather tricked some plants into thinking that spring had arrived. But as winter makes a comeback, many backyard gardeners are wondering — is there anything that can be done to protect budding magnolias and lilacs and emerging daffodils? And will a deep freeze cause lasting damage?
For trees and shrubs, there's not a lot you can do, Buchholz said.
If buds are still closed tight, with their protective scales intact, they might be able to weather a cold snap. And while blooms might fall off, the leaves that follow will likely be fine.
"Unfortunately, it's not like you can throw a giant blanket or a sheet on your tree," Buchholz said. "Our worst-case scenario for our magnolias is if they do start to break bud and bloom early and then we get hit with a huge cold snap, then we won't be able to enjoy the blooms this year. But the tree will still leaf out like normal, and you're only out one year of blooms."
It's not so much the air temperature that gives off spring vibes — it's the soil.
In areas that aren't covered with mulch and that are near the south side of a building, the sun's rays can make the building radiate heat, warming the ground. Once the soil hits 50 degrees, nature's alarm clock goes off. That's why some of the arboretum's daffodils are poking up already, Buchholz said.
In areas that are covered with mulch, the arboretum hasn't seen as many bits of green. Mulch helps protect plants from extreme cold, but it also keeps the soil from warming up too quickly.
"It really buffers the temperature differences, so you don't get that whiplash effect," Buchholz said. "In some of our areas, we use straw mulch, which is messy and you do have to clean it up every year. But the nice thing about the straw mulch is it's also lighter in color, so it reflects a lot of the solar radiation back upwards so it doesn't heat up as much."
For spring blooms making an early appearance, the snow may act as insulation. Adding extra mulch, even on top of the snow, may help. Depending on the depth of the snow — and how low the temps dip — exposed bulb leaves may be damaged.
This wacky winter is just the latest weather event stressing out Minnesota plants and trees. The past five years have brought a succession of catastrophic weather, Buchholz said.
In January 2018, roots froze during a polar vortex. The summer of 2019 was so rainy that the soil became oversaturated. Then came the years of drought.
"We can't win. There's not been a good, middle-of-the-road growing season for the last four or five years," she said. "Here at the arboretum, we've lost about a half a dozen of our absolutely gorgeous older white oaks, which is just heartbreaking."
