This New Year's Eve I'm starting some cilantro, basil, and cutting celery seeds for the basement garden. First I had to make some dirt. Every few years I buy a big bale of ProMix for seed starting. It turns out to be a pretty good deal but takes a little work to make it useable. After a few years I've developed a method.
First I suit up with an old shirt or something similar tied over my nose and mouth because the dust really gets my asthma going. And who wants soil in their snot?
Then I go down to the basement and hack off some dehydrated soil chunks. Old butter knives work fine. I collect the chunks in a plastic tray and take it up to the kitchen sink. If you are doing this outdoors a bucket works better but I can't fit a bucket in the kitchen sink and it is too cold to do outside.
Spray generously with water and let sit for 5 -10 minutes.
Continue stirring, breaking up the chunks with a fork, and adding water until all the soil is rehydrated. Don't rush this part. The soil will almost double in size before it is ready to use.