<<we soak the pots in transplant water in a galvanized tub, remove the physical pot, and gently separate the seedlings.>>
Back in my early years, I tried removing my seedlings while they were submerged in a tub of water. I believe it was Ed Roberts, one of our regional hybridizers, a great man, who had me try this. Don't think I added the transplant stimulant, but I have used it at times.
Could be my habits have been skewed due to breeding rebloomers. I've not found iris seedlings to be delicate so long as they reach a decent size before transplanting, and are not planted in extreme heat. Several years ago, I dropped a seedling, found and planted it the next day. It lived.
From: Vicki <email@example.com>
To: iris-photos <firstname.lastname@example.org>
Sent: Fri, Dec 3, 2010 8:38 pm
Subject: Re: [iris-photos] re: seeds
"I find it easier to remove a thick straw cover than mess with gravel. It keeps the rain from "floating" seed, too. I can lift the straw with the chicken wire and put it back if a sudden freeze shows up as in 2007".
We use pea gravel, it is about pea size and we do not remove it. The seeds germinate right through it. When it is time to line out in the spring, we soak the pots in transplant water in a galvanized tub, remove the physical pot, and gently separate the seedlings. Letting the potting soil and pea gravel drop to the bottom. After that we filter out the pea gravel to use again and dump the used potting soil into a garden area. This prevents damage to the new roots and gives them a boost.