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Aren't temperate Drosera frost resistant?

Joined
Jun 21, 2016
Messages
4
Hi,

I'm posting again about my Drosera rotundifolia plants. They recovered nicely after a heatwave, been growing until a few months ago, then somehow stopped probably due to winter temperatures.
They formed what I thought could be winter rosettes, however after a few colder days (coldest night about 17°F/-8°C) I checked them and they apparently died?
I am not sure if it was that colder night to make them like this (see pictures) since I haven't been checking them for a few weeks and they probably got this appearance earlier when temperatures approched 30°F/-1°C, however I thought they'd have been way more frost resistant than this, hence my surprise.

During growing season I had water level just slightly under soil level but since winter approached and they seemed to have halted growing, I did let water level drop to about the bottom of pots, just enough to avoid letting peat/perlite soil dry completely.

What do you think happened? Will they recover? A couple of them are still greener, but the other ones growing literally side by side (in other pots) are black...why?

Thank you

Alfred

 
Joined
Feb 22, 2014
Messages
1,496
Location
Oregon
The plants look fine to me. I've had hibernaculae of some sundews turn completely brown during winter, only to grow back like normal in the spring. The dense cluster of partly-developed leaves is there to protect the growth point, so even if those get damaged by harsh winter conditions, the growth point can still be fine. You're not even that far yet as I see plenty of green in all those plants.
 

seedjar

Let's positive thinking!
Joined
Dec 11, 2004
Messages
4,067
Location
Olympia, Washington
Even the browned ones don't look entirely dead, so don't give up on them. 18F is not necessarily too cold, I don't think, but the tricky thing about freezing temperatures is desiccation. Cold air has a way of drying things out, and that can be pretty rough on plants with tender leaves. The hibernacula formed by D. rotundifolia is somewhat adapted to dry cold, but in my experience they can be caught off-guard. If the fall or early winter is particular wet and mild, the plants might not be well prepared for a deep freeze. When the cold weather comes on suddenly, I tend to lose a lot more small tender plants like VFTs and small sundews, even if the low temperatures aren't quite as bad.

Whenever the forecast dips below 25F in my area I cover the vulnerable plants, and sometimes even my pitchers. Especially if it is going to freeze without snowing. I also try to keep my pots tightly clustered together in the winter so that freeze/thaw cycles are limited to the top of the substrate as much as possible.

Best luck,
~Joe
 
Joined
Oct 18, 2016
Messages
90
Your plants look a-ok. What would be concerning is if the hibernacules turned soft and mushy. Poke them with a toothpick and if it falls apart readily, your plant is dead.

Sometimes you can't always tell until you check, like with D. filiformis or vfts whose leaves or central points maintain a sort of superficial structural integrity (the fibers of filiformis come to mind, still-green leaves of vfts) but underneath that the growth point is rotten. But this can usually be traced back to a definitive misstep, like underwatering, unsuccessful transplant, stress, or bad soil.

Do the roots of D. rotundifolia (and D. anglica, linearis ftm) disintegrate like those of D. intermedia and filiformis in the winter?
 
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