[Yorkie]

It depends on whether they are hardy annuals or half hardy annuals.  The former can be hardened off gradually to outdoor temperatures; the latter can't go outdoors until after frost is over - early June where I am.

[AmandaLouise]

spencer mix they are.

[Gandan57]

My sweetpeas, from my own saved seed, are in pots outside unprotected day and night. They survived Monday morning`s frost no problem.

They were about five inches high, but have just had a haircut.

[DD.]

We've got some self-set seed in the back garden that popped up in the autumn and have been outside all winter.

They of course have got used to it. Those started inside have to be hardened off.