Storing Vermicompost

Here is a great question from Susan, and something I haven’t really talked about:

What’s the best way to store harvested compost that you
won’t be using for several months? Should it be kept in an airtight

Hi Susan,
Good compost is absolutely loaded with aerobic organisms (mostly microbes, but certainly also some invertebrates as well), so it is vitally important that you don’t completely seal it in a bag or container. If you do this the oxygen will be consumed very quickly and conditions will become anaerobic, potentially leading to the production of various compounds that can be harmful to plants (not to mention the death of your beneficial aerobic organisms).

It is best to store compost in a cool, dry place, providing air flow while not letting the material completely dry out. If it is really moist or wet, you should spread out the material and let it dry for awhile. It should be nice a crumbly and not feel damp when you hold it in your hands.

If you want to put it in plastic bags just make sure to add lots of holes in the plastic to allow for gas exchange. Any sort of bin/tub used to hold compost should also allow some air flow – generally, Rubbermaid type bins have loose fitting lids and some holes near the handles, so you won’t like need to actually drill any (as long as the moisture content is as described above).

Needless to say, compost should never be stored unprotected outside for any length of time. Rain will wash away a lot of the beneficial compounds (nutrients etc), and the sun can dry out the material too much as well. If properly prepared material is allowed to freeze this shouldn’t create too much of a problem – many microbes will die, but plenty of them will simply go dormant, ready to repopulate the material once it thaws out again.

Hope this helps!

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    • Jill
    • October 1, 2008

    I am so glad this was the question today, as someone just emailed that question to me this morning!
    While I wait for my big harvest, I have been storing the rest of the vermicompost in a bucket with a colander on top (used for sifting).
    The packaging I elected to start with once I begin harvesting is cotton drawstring bags, which I am hoping allow adequate air circulation while not letting any compost out the fabric.
    If anyone has any other ideas, I’d love to hear them.

    • Bentley
    • October 1, 2008

    Hi Jill!
    Cotton drawstring bags should work well if they are relatively thick. I suspect something like a muslin bag would allow the material to dry out too quickly.
    I’m thinking of trying out burlap bags myself.

    • Kim from Milwaukee
    • October 1, 2008

    I have purchased worm compost (before having my own setup), and it came in ziplock bags with what looked like pinholes all over it. Seems to keep it at the right dampness.

    • Christine
    • October 2, 2008

    I am going to have to do some harvesting in the near future. My bins have been going strong since the Spring. I think twice a year for rubbermaid containers is pretty good, don’t you think?? Now I gotta think what to do with it. I am doing it the old fashioned way, dumping it out on a table. I will let it sit so all the eggs and hatch out of it and do it again before they get old enough to make sweet love to one another and repopulate the stuff.

    What does everyone else do with the eggs that haven’t hatched?

    • Patricia
    • October 2, 2008

    great topic. I was wondering the same thing myself because I had harvested ALOT of casting and put them into a large rubbermaid without a lid. Things came up and I forgot about them and was wondering how to rejuvenate them if possible. Will still use them one way or another. as for the eggs Christine, I don’t focus on them so much because my concern is the worms but if I see a cocoon I will pick it out and put in with the new food.

    • Jeff
    • October 3, 2008

    Hi guys

    If you screen your vermicompost with a 1/4″ screen, you will screen out all the bigger worms and the bigger bits of bedding not yet completely composted and the eggs and little baby worms will fall through. let the screened stuff sit for a few days. if the vermicompost is too wet it will not go through the screen very well. the next screen you use is 1/8″ now you will be able to screen out 95% of your little worms and eggs. at this point you start a new bin with the little worms and eggs. in a couple of months you will have a second bin in full production!. The Castings that were screened through the 1/8″ screen are the best looking castings you will find anywhere. Just waiting for you to use them what ever way you would like too! top dress your indoor plants, make worm tea, give some to a friend! haha when they see there plants grow like crazy, then the next time you harvest your casting you can give the little baby worms and eggs to start a bin for them..
    or they can buy their worms from bentley….

    • Christine
    • October 3, 2008

    Where do we get these different sizes of screen? Do they sell this kind of stuff in a building supply store? I am small scale and just don’t have the room for a system like these guys built. A piece of screen clamped down in a wooden frame is more my style. I could dump vermicompost on it and gently work it through the screen with my hands. I could have my dad rig something up for me. This would fit my small scale much better.

    • Jeff
    • October 3, 2008

    Hi Christine

    Yes you can buy these size of screens at a building supply stores, that is where I got my screens when I was small scale like you, you can make a frame 12″X12″ and add the two sizes of screen to each frame. This is the way I did it for some time, before I got the bigger harvester. For your own use, you don’t need to get those big harvesters.


    • Jill
    • October 5, 2008

    Christine- I posted about collecting my cocoons out of the old castings when I moved everyone to a new bin here:…..I did it with a large plastic straw with a notch cut out and just kept scooping and scooping. I felt so bad leaving them behind!!!

  1. Thanks for this post. Due to reading a TON of info from this site, I’ve successfully been worming binning since March of last year with no major die offs and not a single escaped worm! (I did, of course, deal with too wet, too dry, too much food, too little bedding…but this site saved my worms several times. THANK YOU!)

    Now that it’s time to harvest, my compost, while mostly composted, is pretty wet and I was trying to figure out how to deal with it. I’ll just leave it very loosely covered, stirring it once a day or so, until it gets to the right moisture level.


    • Bentley
    • January 19, 2010

    Amanda (and anyone else) – you might also want to check out the harvesting section on the “Hot Topics” page since there are links to some methods that might be a little more useful when dealing with wet materials (David’s Tub Method in particular, comes to mind).

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