What to Do With a 4 Month Old Worm Bin

Question from Robin:

My worm farm is about four mo old. Is there a point where I have to start removing some of the composted stuff, or is ok to leave in the bin as long as there is always also plenty of uncomposted straw and food scraps for them to eat? Thank you.

Hi Robin,

I would say that the 4-6 month mark is when you should definitely start to think about harvesting material from your vermicomposting system, or even performing a major overhaul. By this point the habitat quality will likely be on the decline – as more and more vermicompost accumulates – even if there is a fair amount of unfinished material..

Continuing to add food to a habitat that is mostly vermicompost can lead to what I’ve referred to in the past as “Mature Worm Bin Syndrome”. You may find that – one day, out of the blue – your worms suddenly seem intent on escaping, and/or they actually start to die off.

That being said, adding lots of good bedding all the way along (something I think a lot of people forget to do), and scooping out vermicompost periodically from the lower reaches of the system will likely extend the life of the system (potentially by quite a lot in fact – it’s not unheard of to keep a regular tub system going for more than a year). But for best results you may simply want to completely separate the worms from the vermicompost and start fresh OR – if you have room, and an interest in expanding – “split your bin” to create two new systems.

NOTE: Any sort of flow-through system (eg. Worm Inn, vertical migration stacking bins etc) will naturally have a much longer “life”, since the vermicompost is (hopefully) being removed continually over time.

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    • Jes Anderson
    • August 4, 2013

    “even if there is a fair amount of unfinished material.. ”

    If there is unfinished material, what is the best way to get it to finish decomposing? (I dont have a yard, and am giving it to someone who does).

    If I split the bin, do I leave half the worms in one with some of the old compost and then put half in the other with completely new materials?

    That being said, all my worms died when I initially started (4 months ago), so I only have 7 fat ones and a bunch of little guys I am waiting to mature (although, they seem to drain out the bottom and I find them squirming around on the lid, s oI try to save them).
    I am using a standard size bin, and it’s about 60% full.

    Thanks in advance!

  1. I wonder if anyone has ever done a full blown worm bin for over a year without harvesting it. Would be cool to see the side effects of not re-starting a system for a pro-longed period of time.

    • Steve
    • August 10, 2013

    I rotated the material in my worm bin after five months and I am putting new food only to one end of the bin. The thinking here is that the worms will finish up the old material and move where the food is after a month or so. PLUS this movement helps aerate the bin material a bit and encourage aerobic microbial activity. Then I will be able to harvest the vermicompost since the worms have moved out into the new food area.

    • Henry
    • August 11, 2013

    I read an article “Even just opening the lid of a bin containing organic waste can cause mold spores to be stirred up, which, if breathed in, can damage the lungs.”
    Can you tall about it.

    • David
    • August 12, 2013

    I kept a couple of worm bins for about a year. I would add bedding as I noticed that the humidity levels were getting high, the worms started escaping, or small flies seemed to start taking hold. During the end of last winter, I anticipated using the vermicompost for my garden so I stopped adding bedding and slowed down on the food scraps. By the time that I needed the vermicompost, it was of excellent quality and I just had to pick out the worms. (Bentley has some great articles on harvesting worms, so check those out.)

    What I forgot to do was to make sure that I had a good established bin to put those worms into, from their old bin. I used slightly damp, fresh bedding and fresh food scraps. It didn’t take long for the worms to start exiting the bin in mass. I was confused since they were fine in the same bins just days before but with the old bedding. I remembered that Bentley talks about worms being like microbe farmers… they don’t just eat the food scraps, they swallow bits of the food and bedding but get their nutrition from the microbes and fungi growing on the bedding and food scraps. It wasn’t until I put a shovel-full of finished compost into the top of each bin that that worms started to calm back down and they stopped escaping. They were starving even though it looked like there was plenty of food to eat. (I suspect that many new worm farmers will run into this same problem when they get a new shipment of worms but haven’t prepared the bin for their arrival.)

    A way to get around this is what Steve (above) suggests and to put all new bedding and food into one side of the bin and by the time it is ready to support the existing population of worms, it is safe to remove the old vermicompost. I have tried this as well, thinking that all the worms will migrate to the food, but you will likely find significant numbers of worms that never migrate and you still need to pick them out. (At least it stops that problem of escaping worms because the bin isn’t prepared.)

    • Jes Anderson
    • August 12, 2013

    I love this! Thank you for the responses!

    So what I am gathering is that I need to start the new one with my old one, by way of splitting it? This will help get the bacterias going and then transfer to my new(ish) compost to a new bin? My problem is I only have 6-8 fat worms (mature ones), so I’m scared to kill them as I would have to buy new ones. I feel like they are eating and not trying to escape. So I kind of want to keep them going in this current bin. It’s getting full though. And there is newspaper in it still.

    I just dont get how I am going to get this bin to become full dirt so I can give it away (I dont have a yard). AND I have to turn and mix my bin, so do I just turn the new compost without mixing it with the old and develop them simultaneously?

    Do I keep 3 worms in the old one and put 3 in the new?

    Am I over thinking this? haha.

    THANK YOU for your feedback.

    I am so excited that I have turned 4 months of kitchen scraps into dirt and not methane gas in a land fill!

  2. I have a small system in a 5 gallon bucket that has been just sitting for about three years. About once a month or even longer I throw in a banana peel and a napkin or two. Never been changed or harvested and the worms are still quite content – although small. I was even able to use some of the worms in that system to restart my regular 5 bucket systems after they froze solid last winter.

    I’ve read statements like Bentley’s before and heard it from a local place that does environmental education but I haven’t found it to be true for my system that suffers from benign neglect.

    • Larry
    • September 12, 2013

    Does anyone know why the worms fail to migrate to the “fresh” side when a bin is divided as mentioned above?

    I have tried this method as well. I have also noticed that when new food is added, even a nice handful of mushy pumpkin or other worm treats, that many worms stay on the other side of the bin. While MANY or MOST will go to the good stuff, there will be worms, both small and mature, that will not.

    I just finished moving a batch from one bin to a “fresh” one. This last time, I placed a screen type panel plenty large enough for the worms to crawl through on top of my old bedding and layered it with aged horse manure and topped with shredded newspaper. After a few days, MANY of the worms had moved up. But over a third of the worms (at least) remained “below”. I manually sorted a large number by hand and moved them to the new bin.

    Since many eggs were still in the OLD bin, I plan to leave them and will harvest the bin again in a few weeks. This way, the works will be large enough to harvest but to immature to lay eggs themselves. This is a win- win for those trying to build up their herd.

    One observation. Several of the worms that didn’t migrate UPWARD through my screen to the fresh food on top seemed to be of a weaker sort. It could be that most that failed to migrate we’re just content in the area they were bedding, but I have to wonder about worms that still refuse to move, even after a few weeks, to the BETTER food supply. Are these worms OLD? Sick? Or impaired in some way?

    If there is any reason for the failed migration, should these worms just be left out and not transferred to the new bin? Since this only represents a small portion the new bin may be more productive in the long term to use this method to weed out the weak or impaired worms? Less aggressive may mean less productive – consuming less and producing fewer eggs?


    PS: In moving to the new bin. I set it up a short while before the move with new bedding and some starter food. Then I moved the worms that had migrated UP through the screen panel, food, bedding and all, into the new bin. This keeps them in the familiar “home” and they never know they are in a new bin. Seems to work well for me anyway.

    • papajohn509
    • September 13, 2013

    My beds are 36x60x12 and hold 90 gallons. Bedding is 1/4″ ribbon cut shredded newspaper. Feed is horse manure that is broken up and run through a 3/8″ screen from an old combine so there are no lumps except for 1 bed that gets all of the lumps that are left over. To start a new bed I add 3 33 gal leaf bags of bedding with about 30 gal of water. The worms are put in the middle and feed is added when they have gone down. The beds are covered with reflectix insulation to keep in the humidity and keep out light. As the population increases the area where the feed is spread also grows. A full bed will get 6# of feed every couple of days.

    After 3-4 months the newspaper is all consumed and the bed is ready to be processed. The top feed layer is removed, about 2-3″, with the worms that are in it. The rest of the bed is vermicompost and worms. It is run through a home made shaker with an 1/8″ screen. Most of the material passes through the screen but some will ball up and fall off the end with the worms and whatever paper might be left. Each bed will produce 50-60 gal of vermicompost each cycle. It takes under 3 hours to process a bed.

    The worms and balls are returned to the empty bed followed by 2 bags of wet paper and the feed layer removed from the bed. If I need to harvest worms they are much easier to seperate from the concentrated ball material. The new bed is actually a ‘mature’ system from the start.

    I developed a community garden for our small town this spring and plan to use vermicompost sales to support it.

    • Dabernathy
    • September 23, 2013

    Hey everyone. . .I’m the new kid on the block from Florida. . .

    I split my bin after 2 months, but the split was excruciating!! Trying to separate the worms out of the compost, sifting, etc. I almost gave it up. The new bin didn’t seem to be doing so good so I combined them back to a single bin.

    With some input from Bentley, I’ve decided to split my bins, add the required bedding, feed slowly and carefully, etc.

    THE QUESTION! What is the easiest or best way to separate the worms from the compost? Can anyone direct me to an article, or something from Bentley?



    • Bentley
    • September 24, 2013

    JES – Unfinished material simply gets added to the new system (or remains in the original one. Splitting is very easy – you are literally just removing half of the contents (make a split down the middle and dig out everything to the right or left). In the empty half of the old system and the new system you then simply add a heap of moistened bedding – perhaps with a little food waste in it. I would then top everything with a thick layer of dry bedding. So, approx half your original worm population is in the original bin – half in the new bin. Hopefully this makes sense.
    DERMY – I’m sure lots of people have done this without thinking about it (myself included for that matter). What happens will depend on how much bedding is being added and how much food is being added. If not much bedding, but food continually – I doubt you’d make it to the year mark before killing your worms. With lots of bedding I think you’d just end up completely filling the bin with compost before then. Interesting idea though! Could be worth trying.
    STEVE – a great way to get them to move would be to use a food/habitat material that is pretty much irresistible. Something like a nicely aged, moistened, horse manure (several months sitting outside) or some form of “homemade manure”. New bedding with food scraps won’t likely have nearly the same appeal unfortunately.
    HENRY – This is borderline “fear mongering” in my mind (ie by the person who wrote the article). YES, there are situations where there can absolutely be some spores released – and I always caution those with any sort of mold allergies to either be very careful, or not get involved in this field at all. The key, though, is making sure you properly optimize the wastes, you don’t use a lot of certain kinds of wastes (bread, pastries etc for example), and that you always keep everything well buried. People have been doing this stuff for years now (many likely not even following the advice I just outlined), and reports of lung damage among vermicomposters are non-existent as far as I know.
    DAVID – thanks for sharing that! Very interesting! Yeah, this is definitely why I recommend aging a bin for a week or so before adding worms and/or using some form of “living material” to help kickstart the habitat with loads of beneficial microbes. And you are right – this is certainly one of the advantages of the “splitting” method!
    JES – that is not very many worms! But hopefully you have loads of juveniles (and cocoons). If so, you’ll be fine – since they will more readily mature once you’ve got two refreshed bins up and running (more space to spread out and better habitat quality). I am surprised you have so few adults though. Did you add Red Worms to this bin? If so how many originally?
    PATRICK – You’ve highlighted something I mentioned above. It ALL depends on how the system is being treated. Hardly adding any food, and occasionally adding some bedding materials (eg napkins) would certainly be one way to extend the life of a bin.
    LARRY – The splitting method I was talking about above assumes that you are going to leave the old wormy-material in both “new” systems, but if you DO plan to harvest the old stuff (obviously not a bad idea – and probably something a lot of people would want to do so they get some vermicompost) you should try adding something really appealing (like the well aged horse manure etc, mentioned earlier), and also just generally expect to wait for a period of time. Unless you give the worms something “irresistible” they will likely prefer to stay in their familiar habitat.
    PapaJohn – WOW, I’m impressed. Sounds like quite the cool set up and methodology you’ve got there. Thanks for sharing!
    DAVE – As mentioned, the idea isn’t necessarily to separate out the worms when you split – BUT if you ARE trying to get them over to the new half of the bins – again, just add some really appealing materials such as well-aged horse manure (mixed with the usual bin bedding etc).
    There are various ways to separate the worms from the compost – some form of “light harvesting” approach can actually work quite well, especially when it involves migration from one container/tray to another. Be sure to check out the harvesting section on the hot topics page for links to various articles on the topic:
    (at very top of page when you click that link)

  3. I’ve really had no problems keeping a worm bin beyond a year without a total overhaul. In fact, I’ve gone 2 or 3 years before removing compost.

    Generally, old compost is at the bottom and the new material is closer to the top. If you’re always adding, the bin always has someplace reasonably “fresh” for the worms to go.

    When harvesting compost, it always helps to not be in a hurry. When the bins start to fill up to the point where it becomes unwieldy, I’ll start feeding at one end of the bin only. The worms will move over to find the new food. If you’re patient, any new worms will hatch on the “old” side, and migrate to where the other worms are.

    After there are few or no worms left on the side where you want to remove compost, you can do that. You remove compost from that end up until you find where the worms are, then stop. Then, you can either fill up that end with new bedding and food material, or you can level the bin and spread a new fresh layer on the top.

    Now you can use your compost, and your bin is rebooted.

    • Jes Anderson
    • October 24, 2013

    Bentley (or anyone)

    I had 5lbs of worms originally, but I killed all but two because I stopped adding bedding… I’m a terrible person I know! So I have been trying to get my population to bounce back ever since. I have 8-9 fully mature worms, one I affectionately call Fatty. But it’s taken me 6 months to get those guys. I see baby worms in my bin all the time, sometimes they leak out the bottom with the liquid from my bin, but not all of them.
    Why is it taking so long for these guys to get big?

    • Jes Anderson
    • January 7, 2014


    I was feeding and turning my bin every week since April, but got really busy and missed a week. When I went to feed my wormies, to my surprise there were new worms! So for the last two months I have been feeding and turning the bin every TWO weeks and holey moley meee ohhh myyy, there are SO MANY new juvi worms. It’s so exciting!

    BUT…My bin is not turning to dirt. The food is being eaten, but I just have brown ‘almost’ dirt that has bedding still in it.

    What do I need to do to get this bin to be dirt? I’ve already split the bin and my main bin is becoming too big again.

    Any advice I greatly appreciate!

    • papajohn509
    • January 8, 2014

    The dirt is going to accumulate at the bottom of the bin. If you are turning every two weeks you are mixing the dirt in with the bedding. You will never get pure dirt. I top feed my bins with horse manure and have never turned a bin. See my post from 9/13. I have seperated over 3 tons of dirt in a year out of 10 bins and a 4×8 incubator.

    • sam dockman
    • January 23, 2015

    do baby worms have a propencity to travel the sidewalls of a plastic bin?
    while i will be happy to document my 2 month learning curve saga, but saving you all the painful tale, on two separate occasions i have had two explosions of baby worms on the sidewalls — as in a bazillion of babies – well certainly countless hundreds, approx 2 weeks apart. nothing i know that i did the day before to trigger it — i was just wondering if in a mature bin (2 months= no probs) do the babies (ie. 1/4 inch size) prefer the walls as opposed to the bedding.

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