Hello... Fellow Canadian... I live on the west coast... Ontario is such a big province it has 3 different zones.
It all depends where you live in Ontario. If you live in the south, then you shouldn't have much problems with the weather, till about the end of Sept or middle of Oct.
If you live in the middle you might want to consider some strains that will finish about 2 weeks before the others.
They have a FF after their names, for fast finisher or fast flowerer. Just and example... Fast Buds have 5 strains that finish 2 weeks before the same fem strains.
If you live in northern Ontario then you might want to consider auto's that will finish earlier and you won't have any problems with the weather.
Most Indica's have a sleepy quality to them if you let them ripen a little longer in flowering. It will also say in the seed description if they are sleepy or couch locked.
Good Luck.
Chuck.