Outside temps and moving chicks outside

[Buttercup14]

When can I start moving my chicks outside?
Im in central/northern Alberta and the temps are around 0 C at night and maybe anywhere from 8-15 degrees Celsius during the day?

And what about moving them to the garage with a heat lamp? Will they get enough light during the day? There's two windows in the garage.

I have two sets of chicks - 5 week olds (2 buff orpingtons, 2 barred rocks and 2 gold laced wydonettes) and 4 blue americaunas that are 1 week old (the younger are separated from the older ones).

 

[Egghead_Jr]

The 5 week old chicks should be feathered enough to go outside without heat now.