I start by placing the seedlings in heavy shade and progress to less shade areas keeping a close eye on them for any
stress. A light mist also is helpful. I know some use a temporary covering of a tarp or just a plain sheet suspended above until the plants harden.
Good luck,
Felix

Good post. I've wondered how to do this best. Last year, I started putting the potted seedlings out in the morning sun while I was having breakfast and then bringing them in before I went to work. Did that for a week or so before setting them out, partly to harden off and partly because I feared they weren't getting enough sun in the house. But gosh that was a lot of working bringing out and bringing in. The plants all survived being set out in the garden, so maybe it worked... but I sure would love to find an easier way.

I start them outside and keep them outside.
My bench is 2 saw horses with long 2x2's under the mahogany tree.
They stay under the tree until they have some real leaves and a bit of growth. Then I repot and move them to a spot nearby that gets morning sun (the east side of the mahogany tree).
As I've learned many times, vegetables are not houseplants!
They get too spindly inside.
The biggest issue here is when a tropical cyclone decides to come by. Then the flats are houseplants for a few days at least. I hate that.

I start my seeds indoors. As soon as they sprout I have a 2' grow light I put on them 2" above the plants so they don't get leggy. Once they have their first set of true leaves they go outside on my potting bench on the east side of the house so they get morning sun and afternoon shade. A week after that they get potted up and left there for another two weeks, then to the south side under an oak tree for a week, getting afternoon sun. Then full sun for usually another week before being set.

Gee, I would have never thought to start my seeds in the house during the summertime. I start the seeds in full sun so hardening-off has never been a problem. If that way works the best for you guys, then I must be the "lazy" gardener.

Treefrog,

You've inspired me to take the ugly table with the ugly little plants outside in a shady area this weekend. Sadly, my mahoganies are in the front yard and the table, worthless plastic pots and the plants would all disappear out there. Someone would be inspired to "recycle" the whole shebang. But I have good shade by the side of the house... maybe it will work.

I'm still a little scared of this heat, so I'll keep a few indoors, just in case. The heat doesn't wipe yours out? There's no question mine get spindly, I repot a few times before setting them out, sinking the spindly stems each time so they'll grow roots. Am I putting too much effort into this endeavor?
susannah