Re: Relished Feasts
it has nothing to do with the temperature in canada. The regular yogurt sold in stores doesnt have enough live bacteria(it is practically dead) to make the curds out of the milk. What I have heard is that if you want to use the store bought yogurt as starter then you should leave it out for atleast overnight and use it to make yogurt the next day to make/have some of the bacteria.
try this:
Make your own homemade greek yogurt | Chef in disguise
How to Make Your Own Yogurt
I use a starter to make dahi, and then keep using the same dahi as a starter until it is not as fresh anymore and then I make a batch from scratch again. I use a starter for kefir too. I dont use any special equipment or incubator, I only use a thermometer to get the temp right, and then put the container in slightly warm oven(which is turned off before putting in the container with milk and starter, the oven should never be hot or it kills the becertia needed to make dahi)