How do you know if compost is finished?

12 years ago

Hello everyone, just an update on my worm bin; I think I'm doing fine so far. There is no smell, very little leachate, and the majority of worms began to stay in the bedding instead of moving down to the bottom drainage tray. I am seeing a couple tiny "white worms" on the surface everytime I opened the lid; initially I thought they were pot worms and tried to pick them out. But upon closer inspection, I see a little bulge in their mid-section, so I guess they're baby wrigglers afterall. (Phew, I'm working hard to keep a EF-only bin) :D

So, while I'm having fun watching my bin everyday, I wondered how to tell when the vermicompost is finished and safe to use on plants? The main bedding of my bin is coir, I only add paper shreds whenever I feed to soak up excess liquid. So, how can I differentiate castings from the coir? The bedding looked the same to me since day one - dark brown soil like stuff.

I was thinking maybe after the first tray is pretty much full, I will start to harvest. Then I'll let the harvested vermicompost sit for a month or so in a ventilated tub before use; so it can finish off decomposing all the organic matters. I heard unfinished compost contain phytotoxin that will kill plants; is there a way to tell if my vermicompost is safe and ready to use?

Comments (4)

plumiebear
12 years ago
I define vermicompost as a mix of worm castings (vermi) and other decaying organic material (compost). I think VC is ready to use when it has 10-20% worm castings content. How can you tell? You can't really. You have to guess.

For example, if you start with 5 gal. of coir bedding and let 1 lb. of EF live in it for a month under good conditions (with appropriate feedings, temps, etc.), I'd guess that 1/4" screened VC from that bin would be great for plants. Give the worms another month to work on it and it will be even better.

The only reason I'd let harvested VC sit a month would be to allow cocoons to hatch. I have not heard of "unfinished" compost being harmful to plants. I get sprouts in my compost and worm bins all the time; plenty of unprocessed material in those.

Andrew
milocrab
Original Author
12 years ago
Thanks Andrew. About the idea of "unfinished" compost being harmful to plants, isn't that the same reason we shouldn't use leachate? You gave me an idea when you mention sprouts in compost! Perhaps I can throw in a few red beans into my harvested vermicompost, if they all manage to sprout, that will be indication that the vermicompost is good to use! :-D
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wonderpets
12 years ago
This is exactly my question -- since the coconut coir looks so much like VC, telling one from the other seems impossible.

Does coir mash together like VC? Could I maybe perform a "pinch test" to see where I stood?
PeterK2
12 years ago
As long as your not mixing stuff up when harvesting (if harvesting only a portion of the bin), I'd think it should be obvious or pretty well composted if it's not actually VC.

The usual suspect are those pieces of wadded up bedding that got missed. Easy to toss those back into the bin. Veggie garbage long gone to mush and eaten. Leaves, coir etc. if it's been in there for months, it's done either way :).

I have a flow through Worm Inn, and the stuff that comes out is pretty broken up and crumbly except for the odd piece of wadded bedding or big fruit stone. If it's not small and crumbley (and not a stone etc.) it gets tossed back in on top.