how to: best air-pruned seedlings, and easiest to transplant

For an auto, requiring minimal transplant stress.

-planting directly into a 3 gallon air-pruning container (fabric bag/superoots air pot/hercules pot/homemade container/etc) ... which will not benefit from air-pruning until the roots reach the sides/bottom of the 3gallon container
vs
-starting in a very small air-pruning container, which will air prune the roots sooner... and transplanting the plant (along with the already-enlarged root mass) into a 3gallon air-pruning container.

pros, cons
-Direct in a 3 gallon container, means normal roots, normal nutrient uptake, for the 5" of growing it takes to reach the sides of the container. For an auto, it means normal nut uptake for all of that time, also.
or
-Start in a small air-pruning container, and the roots only need to travel 1" to reach the sides, be pruned, and enlarge the root mass. Then after it's transplanted in a 3 gallon container, the enlarged root mass is *aleady* uptaking more nutrients... as it grows out to reach the sides of the container.. which will result in more air pruning.

cons are transplant shock, and extra effort. it seems that the benefits of an enlarged root mass, early on, may be worth it.


How can transplant stress be minimized?
Ideally, some starting container that can be simply planted into a larger container... and the roots can grow through it without being hindered at all. Something that will either crumble, break apart, or be stretchy enough.

-use a homemade cotton cheesecloth 'jiffy pot' to start in... and simply transplant the entire container into the 3gallon. The roots would grow through the cheesecloth... but would it limit or hinder the root growth at all? (transplanting a common fabric bag into soil, supposedly does limit root growth thru the bag)
any alternatives? homemade cup from cotton balls, hollowed out bread bun...

-use a superoots air pot to start in (modify a 1 liter size to be smaller).
cons- not as good air-pruning as fabric. needs to be removed to be transplanted. pros, easy to remove without damaging the root mass.

solution - get a 6" rockwool cube. Cut it to 2"x4" or so. Dig it out to make a cup. Fill with loose potting soil or soil mix, with mycorrhiza.
Use a thick pin or large paperclip end, to poke a lot of holes in the sides and bottom of the rockwool, to increase the air permeability, increase air pruning ability, and allow the rockwoold to be less constrictive after transplanting.

Plant from seed... the seed gets the myco and soil relationship starting right away. Soon the roots reach the bottom and sides of the rockwool, and get air pruned.
Watch for white root tips to be visible and abundant.
Transplant as-is to larger container, with the identical soil mix (no transplant shock due to different medium), and of course with more myco right at the transplant hole.

That way, starting from a few days old, the seedling already has gained an enlarged, full, root mass, with more root fibers and rootlets. And all the time after that, it is able to access more nutrients.

You lost me at "Auto."

In all seriousness: "air pruning" is quite the buzz word as of late. I ordered one of those felt pots online, specifically geared towards the phenomenon known as air pruning. I also planted the rest of the veggies I had in my nornal square 5's. I noticed zero difference. Just my 0.2. I'm now DWC indoors.

By the way, in 15+ years as a grower, I have yet to experience the fabled "transplant shock."