As I write this in late January, it is -11 degrees without factoring in the wind chill in Rockford, which is where I’m teaching, and fortunately not where I’m living. Not that there is anything against Rockford and northern Illinois. It’s just as the British would say, “It’s bloody cold” and most of Illinois has experienced the bone-chilling cold this year.
Old-timers will tell you they grew up with this weather, and I can remember the cold days back in the ’60s and ’70s. We survived with layers and layers and layers of clothing, and piles of blankets in the evening.
Cold spells were normal, or seemed normal when looking at the old USDA Hardiness Zone maps. In the last 20 years, those maps have changed to reflect milder winters.
We know in many cases what the cold means: higher utility bills. From the plant world, it’s a little harder to predict.
Some things are easy and make us heave a sigh of relief.
First, wind chill means nothing for the plants, except for the potential of drying out evergreens, but that’s more of the wind blowing across the leaves or needles, and pulling out water droplets while the frozen roots can’t replace the moisture.
The leaves and needles will die, but new growth should emerge in spring to cover the damage.
So, even though the wind chill gets to the -30 to -50 range, it only affects heat generating entities such as animals and cars.
Next, most of our shade trees won’t be affected. Apples could care less. We need temperatures down in the -30 to -40 range for damage to start occurring, and that only happens in the movies.
Most of the perennials deep in the soil are faring just as well, though snow cover makes a better insulation from the biting cold than bare soil. And we’ve been blessed with little freezing and thawing and the subsequent heaving of the soil which can damage roots.
Some things are easy, but not so good to report.
Many of the spring blooming shrubs and trees may have lost their flower buds. It wouldn’t surprise me if forsythias, lilacs and dogwood don’t bloom well this April. It’s not that the plants will die due to the cold; it’s just their flower buds are out there exposed and freeze out. Come spring, they may not bloom, or the flowers may be puny and miscolored.
All those southern plants such as southern magnolia, nandina, pieris, and crape myrtle that did so well the last 10 to 20 years may not look so good. It’s possible many will become compost fodder. Some may completely die; while others die back to the ground.
Nothing is more vulnerable than apricot, peach and nectarine fruit buds. You could almost bet the farm these fruit crops will be greatly diminished this year. Greatly.
On top of that, it’s possible the cold has penetrated the bark and killed the cambium of the tree, which means come spring, the tree will leaf out and then die. We’ve just been lucky the last 10 years.
When it comes to insects, the weather is a little less exact.
Many insects won’t make it through severe cold, including some of the grubs that can’t move faster than the ground freezes. That includes Japanese beetle grubs.
Insects above the ground have no protection, unless they’re hiding under the tree’s bark.
Of course, the cold may not affect many insects or their eggs. It’s more of a wait and see. And of course, if some are killed, it won’t take long for the populations to build up. Maybe not this year, but possibly next.
So, what can you do? Wait and see. Be prepared that plants may exhibit some interesting effects.
And hope for warmer weather. Until July, that is, when we’ll wish for cold temperatures again.