Personally, I'm not quite convinced in the theory as to efficacy of compost teas... I'm not saying it doesn't do anything, I'm just saying I don't bother with it. My experience has been that worm castings don't seem to provide nutrients fast enough to keep up with heavy feeders... perhaps if you really pile it on, like over 25% . For me, I find the most amazing aspect of worm castings to be its ability to hold on to water. I suggest adding additional organic sourced ferts... and during the cooler months you may even have to resort to chemical ferts until the biology of soil gets going.

I'll be interested in what others here do with their castings in the garden.

I have not tried to grow anything with heavy nutrient requirements, like vegetables, with worm castings. I have used castings a lot for houseplants, outdoor container plants, and my current small garden which is for pollinator consumption, not human consumption.

For containers, I mix in probably 20% vermicompost with the potting mix. In my garden, I have not amended large areas, but add a good portion of vermicompost into the planting holes when I plant things. After that, I top dress with vermicompost throughout the growing season, while layering on new mulch. So far, so good...but of course i have no control garden where I don't do all those things.

I have very little confidence in the idea of "compost tea". I don't think the science is there to show that there is any benefit to the process of brewing compost tea. My idea of vermicompost "tea" is to slosh up some VC in a bucket of water and pour it on the soil, on those occasions when I feel impatient to get some nutrients down into the soil a tiny bit faster. Otherwise, I top dress when rain is in the forecast.

The other special application I have for VC "tea" is for smaller house plants where there may not be room in the pot to top dress the soil. (I don't feed any of my house plants very heavily since I actually have very few and no big ones - not many windows in my long narrow flat on the ground floor of a row house.)

I think watering vermicompost into the soil must deliver a pretty low level of nutrients; having lots of vermicompost in the soil at the outset is a better way to go. In the garden, I'm of course also relying on the free-range worms in the soil to continually eat the mulch and enrich the soil throughout the growing season. I think this is plenty for most ornamentals, at least.

Vermicompost has other advantages besides its NPK and trace nutrient content. Monomer mentioned the water holding capacity of vermicompost, which I think is much greater with fresh homemade castings than for bagged vermicompost products. Vermicompost also contains substances that mimic plant growth hormones, and suppresses a lot of plant pathogens

Certainly using WC or the TEA will help plants, but for heavy feeders like tomatoes its not enough though it can give them a kick.

In my original post I questioned the use of worm tea not because I use it, but because I've read of other people touting it's benefits. Last time I put some nice moist castings in a bucket of rainwater I expected the result to be "muddy" looking water that I could easily add to my rose-beds. But that wasn't what happened. Even with some fairly vigorous stirring the castings remained virtually intact in the bottom of the bucket and the water darkened very little. I was really surprised! Maybe that's one of the reasons they don't make the best fertilizer - they release their nutrients so slowly.

Harry

Slow release fertilizer is a good thing, not a bad thing! And vermicompost retains more of its nutrients for longer than regular compost does. The trick is getting enough of the good stuff down into the root zone on established plants. That's why you still need the living beings in the soil food web to be at work.

It is my understanding that healthy garden soil is loaded with microscopic creatures (bacteria, fungi etc.) that break down nutrients into a form that plants can use directly, whereas a good potting soil is lacking that same microbial diversity (somebody please correct me if I'm way off on that). Is the ecosystem in a large pot/planter really that different than that in a garden or large raised bed?

The reason I'm asking is because I'm wondering if worm castings need those bacteria and fungi to make their nutrients available directly to the plants? In other words, are worm castings only going to provide plant-available nutrients to a soil high in bacteria and fungi like garden soils, as opposed to potted soils?

I'm always hoping that by adding worm castings to my potted plants I'll be able to provide them with plenty of nutrients. Maybe I'm just expecting a little too much from my home-grown castings and compost?

Harry

Yes WC work as a time release and it does hold water . On certain plants I have seen some amazing results but not right away. I put 4cups of WC around an established rose bush that wasnt doing well, worked it into the soil and about a month later it really jumped. If you have it to spare I would add it to certain plants that need it monthly. But I dont consider it a fert.