It's not difficult to harden off indoor grown seedlings...

Use the link below for a method that will also shade your plants and prevent sunscald.

Here is a link that might be useful: Easy Hardening Off Method

Trudi, I wish I'd seen that link before I killed off at least half of the indoor tomatoes and jalapenos. I was hauling the seedlings (on four trays) inside and out, forgetting a day, leaving them out unprotected when I forgot about them, etc.

Thank god for the wintersown tomatoes -- they're tiny but tough.

Caryl

Thanks for the link. I've been gradually introducing them to outside. Since it's too cool to leave them out overnight, and the tomatoes too tall to put under a laundry basket I've been taking them inside at night. Should I still be putting them under my grow lights or leaving them in the dark at night so that they get used to a light/dark cycle?

Link above says If you dip below 45 degrees at night you should bring the seedlings inside for the evening. Why?

I would have thought a much lower temperature than 45°, perhaps "expected to approach freezing" instead. This is just academic musings on my part.

Well, WS seedlings are quite hardy, they were germinated outside and in my experience most can go down to about 28F without damage.

T

You don't need to put them under the lights anymore at night. Actually, even the seedlings will only benefit from 12 hours or so of light a day anyways.

"Well, WS seedlings are quite hardy, they were germinated outside and in my experience most can go down to about 28F without damage."

That low? Shoot! I've been packin' it all back and forth, in and out, with all the frost/wind/rain/snow stuff we've been having lately. Temps have been hitting 30, but no lower. My toms are only a couple inches tall and I've lost a few, I think due to heavier rain, but I guess I'll start leaving them out. Thanks Trudi!

That's the best thing about wintersown tomato seedlings, or any other wintersown seedlings as well: they're pretty tough to weather changes and already hardened off.

My first tom attempt got blown and destroyed in a windstorm, and I had a brick in the bin
{{gwi:334749}}

I re-sowed after that but now they're tiny.

Re: hardening off; Usually wintersown ones are tough and survive frost by throwing a sheet over the jugs. I have lost other wintersown seedlings to frost though, so they do have their limits. When in doubt, I cover with a sheet or stick them in the garage overnight. I think the actual low temp they can take probably is a product of length of time, wind speed, moisture in the air, and God knows what other factors. In my book, better safe than sorry. It's not hard to throw a sheet on them overnight.

Karen