I live in Kansas, where we don't have any weather of our own, we just get everybody else's weather every few days. We don't really have spring or fall, either; just one day it snows 8 inches, and a week later it's 80. So far, in my observation, the temperature fluctuations do not seem to affect my seedlings at all, so long as it stays above freezing. I say that with the caveat that I start my seeds upstairs in a very warm room. I grow them on there until they are big enough to transplant into individual containers. Once they are pretty stocky, I move them to my basement, where the temperature averages between 50-65 degrees and the fluorescents are fairly high off of the plants (say 6 inches or more). This seems to sort of 'pre-harden' the seedlings, in that I note their leaves thicken and they get a bit fuller. Then, I kick them out underneath the carport for a day or so, so they get some ambient light and wind. After that, I spell them out in the sun for a while, depending on what variety they are. So far, I've never lost a seedling during hardening or after planting (unless it was a puny runt that I just stuck in the ground to see if it would make it or not). The only weather that makes me bring the flats back under cover is hard rain, heavy wind, or freezing temps. If it's real hot and sunny, I just make sure they are well watered and ready for hot sun; if they aren't, I put them in a shadier spot for the day. Anyway, hope that helps.

I set my plants out last year in the middle of April and except for a couple of nights when the temps dropped into the mid-40s, never brought them back in. Heavy rains didn't bother them at all and after the first of days, strong sunlight didn't either.

Mike

Do any of you "pre harden" by putting a fan in the room? The spot my garden is in can get pretty windy at times, and I worry about breakage after transplanting. These things are like my children!! ;)

Kim

We run a ceiling fan most days, and windows are open as often as weather permits. Of course I am in Southern CA and not everyone can open a window in March. So I sort of passively had some breeze indoors, but did not need to specifically put a fan on them.

I don't run a fan, no. We get the wind sweeping down the plain here, but my yard is pretty dang sheltered, with houses and big trees and fences all around, so I've never had a problem (knock on wood). It was whipping around pretty good last night/this morning with a thunderstorm, and everything still looks good, with the exception of some calendula that I started too early and it got a bit leggy before I planted it out. But even that is just kind of laying over, it's not broken or anything. So I think the only things you'd have to worry about would be real tall, leggy seedlings, which I guess should be avoided anyway. In an ideal world. :)

Queenofthemountain, your hardening off plan sounds good to me. I'd protect tomatoes from 45* and lower, unless you wintersowed them. I'm wintersowing mine this year, so the seeds are outside now, waiting to sprout. My forecast is for the thirties tonight and 30* F tomorrow night. My peppers are indoors though, and won't go outside until May.

I run a fan, but not all day. I run it at least 15 minutes each day though. I'm thinking about putting the fan on a timer. Air movement helps prevent damping off and other nasties. It also encourages the seedlings to build stronger, shorter stems. If your tomatoes are leggy just plant them deeper when you transplant. You can plant them deeper vertically, or trench them so the stems go in the soil diagonally. Doesn't work with other veggies that I know of, though it might work on other nightshades. Best to grow them short and strong to begin with. One of the tricks I've learned with tomatoes is to brush my hand across the tops of the seedlings. Follow the link for more info. I enjoy the smell of tomato foliage so I like petting my pet tomatoes. :-)

Here is a link that might be useful: Brooklyn Botanic Garden - Sheperd Ogden article