I love seeing worms in my pots.
But worm casings are cheap at the nursery.
Why mess with making your own?
A couple sq.ft. bag is under $20..
Isn't your time worth more than that?
Maybe Ca. suppliers are different,I don't know...
Do you REALLY have to make your own?
As far as my experiances go.IF I have cool soil in my pots,I have tons of worms doing their thing.
When I grew in the ground IF I had good soil,I had worms.
At the time I used Canadian night crawlers for fish bait.
I tossed the not used bait in my garden.
They made moon craters at night when they came up.
When it rained it looked like I had tons of baby snakes all over the place.
I used to electrocute the ground for bait.(google it).
A lot of the stuff people go out of the way to grow in bins or? would do as well in a compost pile or pot with good soil from the start.
But people think if they aren't messing with stuff,it isn't good enough.