Need to keep in mind that hardening off - what you are setting out to do - is a very gradual process. It is done in stages just like kids learning to walk. ;)

Direct sun exposure and wind are the primary enemies to young house-grown seedlings so their exposure for the first few days has to be limited and protected.

So as long as it is well above freezing, find a shaded or dappled sun location OUT OF THE WIND and give them an hour or 2 exposure with close monitoring. Next day if all goes well you can go to 2-4 hours, etc.

Experienced gardeners will tell you that once your plants are fully hardened off they shouldn't come back inside as it only sets them back once again. So most of us won't even start the process until a week or 10 days before they can go into the garden. How long until you will be able to plant these in the garden in your zone 3? Since zone 5 growers are just now setting out their cold- hardys I'm guessing a month or more for you, right?

Dave

Yep Dave. I'm in zone 3 and never plant anything outside intil the first of May. Our last frost day is the end of May so they say, but we usually get one the first week of June. That doesn't bother seeds under the soil, or things that a light frost would bother. Tender things however I plant in early June