I have a couple of warm sunny days ahead of me (80s) and I am going to take full advantage of them. This could be dangerous if I do it the wrong way so I want to take this opportunity to tell peole what to look out for if they want to do the same.
Plants grown under lights are soft and will break easily under moderate winds, and it tends to be windy off and on this time of year. Also, the leaves can windburn easily (looks like sunburn in a day or two)
These young plants tend to lose water quickly so they can wilt and die easily if the soil dries in their small pots.
They also tend to cook under high temperatures. The air temp might be cool, but if they are placed on a patio, driveway etc to harden off the surface temp of those areas can skyrocket in the sunshine.
Taking these things into consideration I go against the hardening off rules and put my little plants out in the full sun all day whenever possible as long as the air temp is above 50.
I saturate the pots with water, they may even be in some standing water when they go out. I may let them go a second day without rewatering if they seem wet enough. A dryish pot will not go outside.
I put the plants on the grass in the yard (not on the patio, not on bare dirt). The transpiration of water from the grass keeps the area cool and the humidity high, wind is also lowest near the ground.
I make sure the area is protected from the wind and I keep a close eye on the wind conditions during the day and the plants come in at the first sign of wilting.