Two nights/mornings in a row (May 29th-30th) we dropped down to 32-29F...UGH!! I had Harlequin Marigolds, Profusion Zinnia and 4'Oclocks planted, both evenings I covered with sheets. The first time I had minimal damage and just pinched out the nasty and the second time it was much worse. Most still have live shoots towards the base, but dang...tomorrow is the 1st of June!! And get this.....there was an area that I had planted some zinnia and completely spaced out covering them the first night and those babies were perfectly unharmed! So on the 2nd evening I didn't cover those same ones on purpose and again on even a colder night, they had minimal damage and the flower buds were left intact and showing color HAHAHA!! Also I didn't cover the same above three annuals I planted down at the old place for the new tenant and some were completely unharmed and some went to black mush. It's all ok though.....I did sow some backups and have younger seedlings of the same and different types that I just brought inside for those two nights and will replace the goners!
Other annual seedlings planted out that I didn't have to worry about were:
Snaps (or short lived perennial for me)
BTW I also forgot to cover the Datura wrightii both nights and they were fine :)