I think the lutea should be fine and will return from the roots the following spring. The caerulea is borderline. It might come back, might not. I've read that the roots are fine to 10 F but who knows. You could always trim it back and winter it over in a pot in the garage or someplace that doesn't get below freezing. I'm just going by what I've read, not personal experience. I keep all my passies in containers inside over the winter, even the supposedly hardy varieties.
Karyn

Hmmm so it's the caerulea I should be worried about? I REALLY doubt that the roots would get even close to 10F here.. I'm thinking it should be okay. Since I had planned to plant them outside as soon as they get big enough/gets warm enough.

I'm a zone warmer than you and the Feb temps were record lows here. I lost a number of plants that should have made it. You could always take cuttings in the fall just in case we have another weird winter. They are so much easier to grow inground. I sunk a bunch of container passies this spring and will life them in Oct to winter over inside.
Karyn

Yes I will definitely take cuttings in the fall, just in case.

Would they still flower the following year though?

Um... p. lutea is native to North America, and is considered the most cold-hardy of all passiflora, moreso than even incarnata. Obviously, if your seed came from a population of lutea that thrives in Florida, then its cold tolerance isn't likely to be as robust as that of, say, Illinois, but you certainly don't have to have tropical conditions for it.

Your best course of action is to hedge your bets--plant some of the seedlings outside in sunny, sheltered areas if possible, and pot up the rest to bring in over the winter. That way you've got a surviving population if the others don't make it.

If your cuttings root then you should have blooms the following spring. You might even have blooms while they are wintering over inside if you have sufficient light.
Karyn

Crap.. I just majorly screwed up, I don't even know how. P. alata is the one I'm talking about, not lutea. x_x

I have no idea where lutea came from... I wasn't thinking when I posted I guess. Sorry for the confusion...

The passiflora that I recently germinated was P. alata and NOT P. lutea. I just realized it when I went to double check the fact that I remembered reading that it was from Brazil and jblaschke mentioned that it was from Florida so I got confused and stumbled upon my mistake. x_x

P. alata
P. caerulea

Sorry again. x_x

Alata is definitely NOT cold hardy but it does winter over under lights very well. This is also a very easy variety to root in water. I take cuttings, put them in a glass of water and set them on a seed mat. They have roots in about 2 weeks. It's one of my favorites.
Karyn

That's good to hear I guess. I'll keep it inside for the first year.. unless it will get big enough to move outside this summer? I don't know how fast they grow so I don't know.

Even if it's not big put it outside when the temps warm up. You could put it ouside now, at least during the day in your zone. Mine have been outside 24/7 for the past few weeks with no problems and we've dipped into the low 40's a number of times. They do so much better and will probably grow faster and be stronger outside. My P alatas grow fairly fast and get fewer but thicker stems than many of my other passies. My platyloba has a similar growth habit.
Karyn

Actually it germinated outside. I think me moving it outside was what actually made it germinate, the warmth I mean. I meant that I wouldn't plant it in the ground this year (not keep it inside, though that's what it seemed like I was saying.)

I'm not very good at talking lately. :P