Lots of discussions here about how-to harden off if you want to read through some of them. There is a FAQ as well. Will they recover? Most likely although you will likely lose the leaves that were damaged.

You'll discover in the reading that bringing them in and out stresses the plants and doesn't result in actual hardening off as they have to keep adjusting to the environmental changes. That is why it is recommended that it begin only a week or so prior to your plant out time. It is best to wait until the nights are consistently in the 50s so that once they go out they can remain out except in cases of severe storms and such and then they can be brought in if needed for that brief period.

As a general guide hardening off takes a week to 10 days and depends on what set up you have for doing it. It is a very gradual process done only for an hour or so the first day gradually increasing the time. Beginning with shade then partial sun and into full sun only after they are well adjusted.

Also keep in mind that winds are as damaging to them as sun so some sort of protection may be required to block wind.

Dave

I'm definitely a new guy at gardening, but I was wondering what was wrong with hardening off the veggies as it says in the FAQ's? Is that not an ok way to do it. I was going to start that way tomorrow with my Brussel Sprouts and Onions that have been growing under lights for three weeks...

what was wrong with hardening off the veggies as it says in the FAQ's?

No problem with it at all if you can make that particular method work for you and if you follow it in detail. As I said above it all depends on what set-up you have available to you. Some have screened in porches, some have a shady under-deck, some have lots of shade trees, many have none, some are more exposed to high winds than other places, etc. You have to evaluate your hardening off environment individually.

For example under a laundry basket sitting under a shade tree is very different from under that same laundry basket in the middle of a treeless front yard.

Dave

Thanks for clearing that up Dave. I should be fine I'm assuming. I have no trees and an open yard. This year is a big trial and error phase for me. I have about 25 peppers (bhut, sweet, habanero) all coming up. As well as sprouts and onions.

Everything seems to be doing very well under 16 hours of light a day. The last thing I want to do is lose them because I didn't harden them off correctly. Thanks again for the info...

I just want to mention that peppers don't do real well in cool weather. I'd err on the side of getting them out a little late than a little early.