I'm not familiar with the Home Depot worm mixture. Making your own tea with worm castings is probably fine. Never made worm tea as I have no room for this type of project, however, I use the Our Vital Earth worm tea which has the trace elements added to the concentrate.
I've been using this worm tea for several months with good results. The mix is concentrated to be diluted 50-1. That's only about 1/3 cup mixed with a gallon of water, or 1 oz for a quart sprayer for misting.
I mist a few times a week and recycle the tea after watering - that is, I set the plants in a container, water thoroughly, and pour the run-off back into a gallon size milk jug to be used next time. Recycling the tea until it's time to mix up a new gallon makes it much more economical. There were a few questions regarding the transmission of viruses by this practice, however, Jerry has been doing this for quite awhile with no problems, and my results have been postive.
I have about 30 orchids, a dozen of them being small, and I've used less than half the quart bottle of concentrate, so this seems like a more economical buy than that of Home Depot. Admittedly, my climate is cooler and watering this past spring has been less frequent than those of you living in warm areas. Obviously, if you're watering 3-4 times a week, you'll be using more tea.
Worm Tea testing – follow-up - WOW