Some time ago I was out in my garden after a hard frost and noticed that the wild lettuce was not only still alive, but had liquid water on its leaves while everything else was iced over.
It seems to be specifically designed to handle extremes of both cold and heat.
What plants have you noticed that have extreme temperature tolerances, and do you know what processes they use? What are the survival techniques that you have observed?
Arugula
Austrian winter peas
Brassica rapa (turnip, bok choi)
Carrot (-ish)
Claytonia
Common mallow
Dandelion
Dwarf mallow
Endive
Fava
Garlic
Leek
Lettuce
Mache
Onion
Opuntia
Papaver somniferum
Parsnip
Radish
Radichio
Rye
Spinach
Stellaria media (chickweed)
Violet
Woad
What is âextremeâ in your mind when you think âextreme coldâ? For some people, -3C is extreme cold. For me, not really⌠I have fava beans that resumed growth after -18C (but gave up at -22, ⌠well, in their defense, they never got a chance to thaw from that one as it stayed with us for quite a while).
To learn more about how plants cope with sub-freezing temps, I recommend Life in the Cold by Peter Marchand
Everything is relative. -18c isnât that extreme in the grand scheme of temperatures that occur on earth, but for a plant that produces beans to be growing at that temperature is extreme!
And favas donât tolerate much heat at all. Theyâre just experts in the -18c to 10c range (0F to 50F).
Many types of Opuntia can tolerate both extreme cold and extreme heat, which I think is pretty cool. They stop growing when itâs cold, however-- They turn red, shrivel up and go to sleep. I think they start growing again above 5c, like most plants.
This is a very different strategy than the fava, which remains juicy and green and puts on growth during freezing weather.
No real winter this year here so far, no snow and only down to -5 - -8 degrees C at night, but this is what I collect on regular basis now from the garden.
Iâm curious about the techniques plants use. In the case of the wild lettuce I presume it is the latex in the plant.
Some plants curl their leaves in hot weather. Others use colors to reflect the sun. In the case of favas, I suspect itâs also something chemical. Some go dormant and lose all aboveground growth, while others draw their sap into the roots and allow the above ground material to remain alive.
Some techniques are chemical, some mechanical.
Last I looked, carrots, onions, garlic, kale, what I call broccol-ish and a few lettuce plants were hanging on, not sure what else.
This is the most winterish winter we have had for several years. We actually have snow on the ground and have going on three weeks. It hasnât been above freezing for that time either. Nighttime lows have been hovering around zero F plus or minus three or four degrees. A bit of a warmup is predicted in the next few days. Under snow, I imagine all of the above will still be OK. I have some lettuce in pots on the south facing patio too, itâs doing fine but I didnât expect any in the ground would make it but now I think a handful of plants might.
Certain polysaccharides provide some protection from frost damage. Ask Gemini or ChatGPT about it. ChatGPT can access more up to date research on the live web.
Eastern skunk cabbage is actually capable of producing its own heat, through a chemical reaction in its roots I believe. Though as an edible crop it has to be boiled repeatedly to remove the stinging and toxins. Not bad for a famine food though.
I could imagine the smell of boiled skunk cabbage. Iâd rather eat bark lol. It is one of the first plants up in the spring around here.
