Cold hardiness of potted plants left outdoors in winter

David Pilling
Tue, 09 Oct 2012 04:16:43 PDT

A fresh look at ebay, revealed that temperature loggers are now 
available at low cost. They're a small device which will run for a year 
off an internal battery recording the temperature every so often and 
they can be plugged into a USB port to read off the data.

So discovering how low the temperatures underground go is now practical.

Oddly I recall an undergraduate problem I was given which gave a 
mathematical model of temperature variation in the ground - a lot must 
already be known, but of course not under anyone's precise 

I doubt it would be of much interest if I carried out this experiment, I 
have a poor man's version, I leave dahlia tubers just under the surface, 
and these usually survive.

In the two "worst winter for 30 years", 2009-10 and 2010-11, I lost a 
lot of bulbs on shelves in the greenhouse, but the bulbs I would expect 
to survive, narcissus, galanthus, tulips, crocus in pots all survived. I 
still think they are hardier than others.

However in those desperate winters, the minimum temperature was around 
minus 5C, that's with living close to the sea in North West England.

David Pilling

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