[brannelford]

^^^ I'm not sure how old you are, but I've lived in Toronto for several years, and I'm old enough to remember years where the temperature in Toronto has dropped to -30° C or colder. In fact, throughout the 70's, 80's and early 90's, it wasn't uncommon to have the temperatures fall deep into the -20's and even below -30°

For the past decade, Toronto and areas around here have been blessed with winter temperatures that have been significantly milder than normal, so much so, that I fear some people assume that this milder weather is the new normal.

It's still too early to tell if this recent spate of milder than normal winters is indeed a new norm; but I suspect, given the law of averages, that at some point average winter temperatures will eventually revert back to the mean. This implies that at least one winter in the near future will have colder than normal temperatures, and if that were the case, then without question, any outdoor palm or tropical plant in the Toronto region would be killed... root, stalk and all.

Given this law of averages, it is therefore prudent to over-winter one's tropical plants inside a greenhouse, especially if the goal is to keep them growing for more than one year.