Hardening Off

Is it necessary to "harden off" plants grown inside the house? If so, how would I do that?
And finally, if they do need it is that why the last batch of plants I transplanted outdoors died?


Thanks a lot everybody.

 

The ones that stick in my mind are my anemone plants and all of my morning glory plants, there may be more. It's the morning glory that hurt the most and it's them that I'll be planting out in the next few days.

So how do I do it?

 

I've lost plants that were hardened off in the past few weeks. Thought they were hardened so planted them out, then came days and days of relentless cold winds.

Given up on some of them now, they wont recover in time for this season:DOH:

 

I'm doing as you say, and that plant pot is outside in the sun and I'll bring it back in when the sun goes down. The plants are drooping though, is that normal? Yesterday I had them outside in the shade and they didn't droop but I thought full-sun would be better for them.

Also, what do I do if or when the plants outgrow the pots during the 10 days? The pot they're in is only 3" and the biggest plant is 2-3 times that height.