This entry was done in 2009; I'm adding this little blurb in March, 2010, for all you people who ended up here by way of Google: A hard freeze will not hurt your tulips. Put your fears to rest.
I knew we were in for a hard freeze last night. All my tulips are up, so I went looking on the Internet to see if I should cover them. The answer was "no".
This morning when it was fourteen degrees, I bent over and touched a tulip blade. It was rock-hard, and it seemed strange to me that any plant except grasses would be able to totally freeze like that and still have life in it.
A couple hours later when the ground had started thawing, I once again touched the tulip plant; it was no longer frozen, and looked and felt absolutely normal, as it does this evening. We're supposed to get another hard freeze tonight, and I assume it won't do any damage to my tulips either. I do know that a freeze while they're blooming destroys the flowers, but it'll be awhile before they bloom.
I don't have a lot of experience with tulips. I tend to stick with easy annuals like impatiens, marigolds, pansies and such; or else flowers that come back year after year, requiring no effort on my part, like iris and peonies and tall phlox.
Tulips really aren't cheap, and they're only good for a couple of years. But I do love them, so last fall I splurged.
Once we get out of the current cold snap, I'll have a report on the lettuce and radishes that were up last weekend.