Properly hardened off, hardy perennials can handle a continual stretch of nights below freezing. If the nursery has had them outside, they will be fine.

The problems are if it gets very cold. Around 25F, or so, even the hardy plants can get damaged. Depending on where you are, those temperatures may be normal for the next week or so. Here, we usually don't start planting growing plants until the last week of April, first week of May.

Generally, there is a world of difference between simple frost for hardy plants and cold enough to cause damage.

young perennials newly acquired from a nursery and put in the ground can survive a frost or two?

==>>> depends if they come out of the hothouse .. or were previously hardened off as per above ...

let me put it this way ... in z5 MI .. we always went out on mothers day.. and bought the flats of flowers and went home and planted mom a flower garden ... and if i am not mistaken.. that is mid may ... just because this spring has been warmer.. does not mean that you should be planting ...

all that said ... here is the rule: JUST BECAUSE YOU BUY IT.. DOESNT MEAN ITS TIME TO PLANT IT ...

i used to have a wagon in the garage ... with a 3 foot square piece of wood on it.. and could hold quite a few plants/flats.. and they went in and out of the garage .. until near the frost free date ... and it was also a function of the hardening off process ...

and that is what you should be doing ... if you want to avoid all the worry .... and that is the key .. whether or not a certain plant can take the cold is not relevant to the worry quotient ...

ken

When I was living in the northeast I found the best time to plant perennials was about six weeks before the last frost date. Gives them a nice head start for the growing season.

Obviously the plants have to be hardened off first if they came out of a greenhouse but if you have a trustworthy nursery that you shop at just ask them where the plants came from or how long they have had them outside.

clematisintegrifolia wrote:

When I was living in the northeast I found the best time to plant perennials was about six weeks before the last frost date.

So for me in zone 5b that would correspond to anytime now.

I planted a serious bulb garden this fall which included mixed lilies. The warm spell we had encouraged the lilies to reach a height of 6 inches. Then we got hit with a freeze for 2 nights in the teens and the parts of the lilies above ground were frozen and bent over as if broken. They were brown. Did I lose my lilies or will they try to emerge again?

You really should start your own thread and not hang on the bottom of someone else's.

The lilies will be greatly weakened and may or may not send up new growth this year, but should survive if undisturbed. It may take 2 or 3 years to recover from this and build up their reserves again though.