worm castings are never 'unhelpful', and 'worm tea' that explodes a bottle is the 'snake oil' - the only thing that will burst a closed bottle is something that is fermenting in a way that is creating gas, pressurizing the container, which is the result of yeast, not bacteria .... usually folks make aerated tea, which causes rapid bacterial growth, and when you remove the aeration, the bacteria die, or you end up with only anaerobic bacteria [not good] ... OTOH, if you've added simple sugars like soda pop and/or alcohol [like some do], even molasses, yeast can ferment them in the absence of air, hence the explosions ... and yeast isn't too helpful

keep it simple, you won't produce 15 pounds altogether in less than months, let alone 'per tray' unless you harvest before necessary, and just add what you do get to any space you have ... I'd suggest you'd be better off with the rubbermaid tub style bin, as described in numerous posts here

Bill

Some companies sell worm tea that is really only the leachate dripping out of the bin. This may be good or bad for plants depending on what was in the bin and what actually dripped through. Real Worm Casting tea would be brewed by soaking castings in water. If you seal it tight in a bottle, you kill a lot of the good microbes that are a primary purpose of using worm products.

Unless you really are planning a comercial operation of worm farming in your spare room, I doubt you are going to be buried in castings. Remember that you have to feed the worms a fair bit to get that kind of production of castings and you need a large number of worms in order to produce it. Also, 15 pounds of castings isn't actually that much, perhaps three gallons (provided they are wet instead of dehydrated.)

If you have not yet spent any money, I too would suggest building your own small bin to get the feel for worm farming. It could be a rubbermaid bin or a home built wood bin. (we built a 2' by 4' plywood box on legs for our worms.)

We started small with 2# of worms and only filled up half of that plywood box. After 3 months it is starting to look like we should add bedding and food into the other half and eventually we can harvest from the original half.

Things I have learned from my first three months of worm farming.
1- You don't actually need to water them very much as food provides most of the moisture necessary so long as the original bedding was appropriately moist.
2- If you overfeed, it will get hot and stinky in the bin. (make sure to leave a "safe" area of the bin where you don't feed so that the worms will have a cool place to wait out the heat if they need.)
3- shredded paper clumps so make sure to mix it well with other stuff. I like cardboard bedding.
4- There are likely to be many other critters in the bin. Most of em may indicate something about the conditions but generally are not a problem in and of themselves.
5- Here in zone 9, outdoor worms like an ice bottle in the summer if you can manage it. They will survive without though.

Thanks much for the input.
the recipes I've found for "worm tea" did cut it with molasses and aireate it in a small chamber.
Any ideas for worm tea? Does it have a shelf life?
I've heard of people watering with tea exclusively, with amazing results. I think it'd be cool to try a few tests on next year's seedlings.
Thanks again

I'm sure worm tea (or at least the live beneficial microbes) has a pretty short shelf life. Like most any garden tea, you want to use it pretty quickly once it is ready to get the most benefit.

The worm teas with molasses that is aireated is usually done to try and breed very high numbers of the beneficial microbes. As soon as you seal something like this into a bottle and put it on a shelf, the beneficial microbes start dying.

As to what good a tea is after it has been sealed up, well you might have to test out the idea. Check for nasty suprises when you open the bottle at a later date.