If you didn't already know about worm castings, you probably wouldn't be looking at this page. You already know how great they are for house plants - none of that salt you get from chemicals on the surface of the soil or on the outside of the pots.
You probably already know that the NPK analysis is all below 2%, but that there is something about castings that make plants thrive.
Three-quarters of an inch on the surface of each house plant or mix them with tiny seeds like carrot when you plant them or make a one-cup-to-a-gallon-of-water infusion for foliar feeding.
It's great stuff