I live in Western NY State so I have very similar conditions to you. I have a room in between the house and garage that is unheated and uninsulated. I use it as cold storage most of the winter for fruits and veggies. While it is warmer than outside from the residual heat from the house, I would not keep young starts out there yet. They would fare rather poorly. Basil would certainly not survive freezing and the others would most likely not survive freezing temps as well. Seedlings are more tender than mature plants.

If you want to vacation them in your patio enclosure during the day on mild days go for it but don't forget to bring them into the house at night. But for the most part, wait. It isn't warm enough yet.

FataMorgana

I think I'll wait a little longer. The early March temps are slightly above average right now. The nights havent been below freezing in perhaps a few weeks. Either way I dont want to get forgetful one night and leave them out to die. Not after all the time I've invested in them.

We are geeting closer to April and I'm getting a little more anxious to get my herbs out of my house and into the enclosure to take advatage of the added heat and ample sun. Its about 58 degrees in my patio enclosure(ar 830pm) and about 44 outside. Its about an hour after daylight and almost 2 hours since sun down. I'm going to keep checking on the temp difference bewteen my enclosure and the outdoors. A 10 - 14 degree difference is pretty darn good butI dont know how sustainable it is through the night. Having said all that I dont want to put them out to early and lose them either.

You are aware that herbs like most plants need to be gradually exposed to open sunlight? You might want to start taking your plants outside on warmer days but put them in a shady area at first then gradually increasing the amount of direct sunlight. Even with them being in an enclosed area putting them in direct sunlight can cause overheating.

Putting them out and taking them in is just part of the gardening experience.

Just because your night time temperatures are so moderate now, doesn't mean that you won't have more very cold times ahead of you...considering your zone.

Call your local extension office (see attached link) and ask what the expected last frost date is in your area.

Here is a link that might be useful: Click here to find your County Extention Office

I know my last frost date is in May - I don't expect yours, matthew18, to be much different.

I usually wait until near to memorial day (end of may) to put the out tender items without protection. If you have cold frames or other protected means (like your situation), earlier would be possible. But since we have had ice and snow storms in April and snow after mother's day in the last dozen+ years, it is up to you to be vigilant in keeping track of night time temps or using some tricks to keep nighttime temps from bottoming out in your enclosure. Check out how unheated greenhouses deal with temperature fluctuations.

FataMorgana

Here is a link that might be useful: Last frost date by zip code

I like the last frost by zip code. very nice tool. Like the most of you I typically put my plants out at/or around Memorial day. I just keep an eye on the weather for April and May and wait :)