My question probably doesn’t make a lot of sense, so let me explain.
For the past week or so (and even before, but not quite as extreme), the temperatures around here (southern Ontario) have been way, way above normal. Over the last few days we’ve had temps in the mid-70’s (23 to 25°C) which are an order of magnitude higher than the long-term average high of around 40 degrees (4°C). The daily lows have been correspondingly high, around 55 to 60 (13 to 15°C), with long-term average lows in the mid-20’s (-4°C). So, what’s happened as a result is that there’s been an explosion of buds, shoots, etc.
There’s a good chance, obviously, that we’re gonna get back to weather reality, or even get some below normal temperatures, in the next weeks. And that means there will be a bigtime freeze. So, my question again - if this freeze happens, is that it for those plants and leaves that had started to bud? Or will the trees send out new buds to replace those that will be killed? Will that be it for all the tulips this year?
I am sure the answer is it depends on the plant. We grew peaches, apricots and apples at my house in New Mexico when I was growing up. The peaches and apricots would have greatly reduced yield every few years because of a frost killing off the flowers. Those tree did not bud again that year. The leaf cover seemed to be OK every year just some years the fruit did not come.
From my experience, leaves will come back, but the plant often won’t put on as much growth that year as normal. For flowers that only normally flower once a year, a frost killing the buds tends to mean they won’t flower at all that year.
Small buds often survive better, so it depends how far along your tulips are.
It’s more impressive in Celsius (which is what we actually use). I mean, usually it’s, like, 2 or 3 degrees Celsius in mid-March (when the “heat wave” started). So, 25 degrees (which is actually what is was yesterday!) really does seem like a whole other order of magnitude. Still, I see your point. I guess I was being somewhere between literal and figurative.
Agreeing with what’s been said, most woody plants will leaf back out at some point although not as densely. Healthy plants have enough reserves to put out enough replacement leaves to get them through the season. Flowers on those plants won’t come back though and fruit bearing plants will yield very little, if anything.
Soft-stemmed plants are another story. Perennials with established roots will be fine. Not happy but they should come back. Annuals will likely die and need replacement. That includes your vegetable plants and flowers like petunias, impatiens, marigolds, etc.
Most plants can take some cold snaps though. The “last frost date” around Chicago is officially May 15th and trees and shrubs start leafing well before then even in a normal year. Plants suited to the climate should survive just fine; I wouldn’t even assume a single hard frost will take out the leaves of climate-appropriate plants although a sustained cold spell may do it. I wouldn’t be fooled into spending a lot on annual flowers and tomato plants yet, though.
Even in woody plants like trees, there is some chance that a severe injury could leave the plant permanently debilitated. In the days of my youth, we had two beautiful Chinese Elm trees. One year, one of them got utterly eaten alive by caterpillars. That tree never recovered for the rest of its life – It always had extremely sparse foliage, year after year. I’d worry that an ill-timed frost might have a similar effect.
As a youth, we had two large crab apples (the kind that make real edible fruit, not the ornamental) and they were defoliated every year for about four or five years in a row by Eastern tent caterpillars. But each season they bounced back… guess they were just accustomed to it.
It’s quite astounding what’s going on around here. The flowering plants and trees exploded today (I’m no expert but I think I was seeing lots of azaleas and magnolias, for example. Usually we don’t get much, if anything along those lines, until very late April or May). Never, ever, I have seen so much “spring” action so early. I hope it’s not a disaster waiting to happen.
It may seem that way, but your terminology is incorrect. The only way to legitimately talk about temperature being a given factor or order of magnitude greater than another temperature is to use an absolute scale.
So if your temperature is usually 2-3 degrees Celsius in March, that corresponds to 275-276 K. You state that your temperature yesterday was 25 degrees C, or 298 K. So the temperature is about 8% higher than normal. It is not an “order of magnitude” higher. If the temperature was an order of magnitude higher, it would something like 2,750 K, which would be much, much hotter.
That’s been my concern all winter - I’m a plant person, and this is definitely NOT what the plants are used to, and plants like what they are used to. I hesitate to go all “AGW scare-monger,” but one of my biggest concerns for climate change is the loss of healthy plants.
We had a daffodil that came up over and over one spring - after I think it was three times of trying to come up and getting frozen, it just died and that was it. It never came up again. I learned my lesson from that - if my plants near the house start coming up too soon, I make sure to cover them back over if I see it’s going down below zero at night again. The lilacs here often get a frost after they put out buds - if that happens, we have a very lean year for blossoms, but the trees seem to do fine regardless.
Most plants (especially native to your region) are well-adapted to freakish weather - otherwise, an unusually warm or cold stretch in spring as they’re getting into active growth would have wiped them out long ago.
We have magnolias in full bloom here that normally would be flowering close to two weeks from now (and susceptible to late frosts/freezes even then). Pears and cherries are similarly in heavy bloom and the first lilacs look like they’re maybe a couple weeks away.
As an example of a native tree that’s a real trouper - 7-8 years ago I planted a redbud (Cercis canadensis) intending it to grow next to the driveway, then realized it would get too broad and spreading for that spot. So early the next spring I transplanted it to a better location, losing maybe 1/3 of the root system in the process of digging and moving it. A couple weeks later after it had leafed out we got a hard freeze and most of the foliage died. It resprouted leaves, but then we got into a bad drought and I was watering as much as I could, but without a lot of hope after all that trauma. Now the tree is about 8 feet tall and close to that in breadth, as of today.
I wouldn’t worry much about things getting killed back by a late freeze, though if a lot of negative factors coincide (way too much or insufficient rain, lots of bugs etc.), then marginal performers/plants poorly adapted to the region might get into trouble sometime during the season.
