I use them as an additive when I till the veggie garden and sprinkle them on flowers when planting. At my former home I made worm tea throughout the growing season, too, (dissolved casting in water) and sprayed on plants to fertilize, but in my new spot the soil is rich with worms so this is not necessary. I can't say what the results would be without the castings, but I find them a good alternative to commercial fertilizers. I don't usually buy garden soil as I mix my own composted manure, peat moss, vermiculite, and top soil w/ castings and bone meal. If you're using soil that has extended-release fert mixed in you may not need castings until the fert has run its course (usually 3 months after first watering). Hope this helps!

I just bought a bag of worm casting (expensive!) I'm going to sprinkle a little bit of it around my plants after this rain finally stops. Will let you know how if I notice a magical growth spurt. Can't wait to hear what every body else thinks about it...

They can be very expensive. Sometimes contacting the producer directly and buying in bulk can be more economical. Also you can start your own vermiculture bin really easily if you like the results!