Answer: Alstroemeria is only winter hardy to USDA winter hardiness zone 8 (a few may be slightly hardier than this especially if planted very deeply, but in general zone 8 is the rule), so there is nothing you can do to get them to survive the winter outdoors in Ontario. If they are in a container you might be able to bring them indoors and store them in a cool, dry area until spring. Or, you might be able to dig them up and store them but the roots are quite fragile so it is difficult to do this successfully. If you want to leave them outside and give it a try, you might heap a deep layer of mulch over top and hope for the best -- if there is a steady, deep snow cover and you planted one of the hardier types it might possibly work. In cold winter climates such as yours most people consider them an annual and replant new ones each year. I'm sorry I can't be more encouraging.
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