Worm castings as growing medium?

[melodious fellow]

About 3 years ago, I tried worm castings with perlite for seedlings and clones once. Made a muddy mess, and nothing grew.
By the looks of it after the attempt, the castings clogged up the perlite, and so it got no areation.
Still use it for my soil mix, but after buying 15 lbs I still have most of it left.

I read in a grow guide once that worm castings were the ultimate soil supplement and that they were so rich, one could grown in pure worm castings. It also said that they were so expensive though that this would be way impractical.

But after reading Stinky and Rusty's experiences, fuck that