March 2008

Worm Bin Depth

This question comes from James, who is curious about the ideal depth for a worm bin.

The question I have for you is in regards to how deep a compost bin
should be. I’m using a basic rubbermaid bin setup that is about
10-12″ deep, and have shredded newspaper up to about 8″. Is this too
much bedding? The worms seem to only congregate on the bottom few
inches with little activity in the top layers. From material I’ve
read, the worms will typically avoid the top inch or two, but I was
surprised that there didn’t seem to be any in the middle portion of
the bin.
The only guess I have is that it has something to do with the
basement temperature. I’m using a double stack method and the area
where the worms are would have an extra layer of insulation from the
cold basement air, but I don’t know how much that would affect
things. I would be grateful for any insights you might have.

Hi James,
A depth of 10-12 inches sounds good, assuming the bin has a decent surface area. Just to give you an example, the “new home” for my European Nightcrawlers has a depth of 8.5″, with upper dimensions of 20″ x 13.5″. I was actually very surprised to find such a perfect bin (it is a Rubbermaid Roughneck), since most Rubbermaid bins tend to be too deep for my liking.

Layering your bedding to a depth of 8″ definitely sounds good to me. When I start up a new bin I will put in enough bedding (and food materials) to bring the level close to the top of the bin. I assume you have food (scraps etc) spread around in your bin as well? Worms tend to congregate in the vicinity of the best food source and/or areas of adequate moisture. If your worms are all down at the bottom I would predict that there is something appealing down there foodwise, or perhaps that the rest of the bin is a bit too dry for them.

I personally haven’t found that worms avoid the top 1-2 inches, unless of course there is dry bedding and no food up there – again, it really all depends on the way you maintain your bin. If you bury all your food down deep the worms will likely stay down fairly deep as well, but if you layer it near the top (generally what I prefer doing) you’ll find more up there.

Unless your basement is really cold I wouldn’t suspect that their location was temperature-dependent. The warmest zones in the bin would generally be in the areas with the most microbial activity – i.e. where the food materials are concentrated.

Anyway – hope this helps, James!


[tags]worm bin, worm bins, worm composting, vermicomposting, food scraps[/tags]

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White Growth on Worm Bedding

This question comes from Peter. He is a little concerned about some white fungi growing on his worm bin bedding.

I used damp cardboard as bedding material. But after some
time, I notice the growth of white moldy substance on some pieces of
damp cardboard. Can you please tell me what is the cause please? I
fed my worms with freshly chopped vegetables like cabbage, amaranth,
soybean pulp, etc.

Hi Peter,
It is important to remember that inside your worm bin is a complex ecosystem, chock full of countless varieties of microorganisms, such as fungi, bacteria, protozoans – along with many larger creatures, such as mites, nematodes, and of course the worms themselves. You may not see a lot of these organisms most of the time, but occasionally some of them will make their presence known when conditions are really to their liking.

This ecosystem is vitally important for the proper functioning of a worm bin. If you’ve ever tried to add worms to a totally new worm bin containing only moistened bedding along with some fresh food scraps, you may know that they often try to escape – this is why I recommend aging the bin before adding the worms. This way, by the time the worms are added there will be loads of microbes for them to feed on.

In your case, I would guess that some type of fungi (many different species can be white and moldy in appearance) is simply feeding on the cardboard soaked in the juices from the plant materials you’ve been adding. I definitely wouldn’t be concerned about this, unless of course it completely takes over the bin and causes the worms to want to escape (I have yet to see anything like that happen – I always view a decent amount of mycelial growth as a good thing).

One thing you would want to avoid is excess growth of green or black molds (especially the latter), since inhaling large quantities of their spores isn’t something you want to do on a regular basis. The good news is that large growths of mold only seem to occur when too much food is added, and when certain types of food are added. For example, if you added multiple slices of bread and simply left them to sit at the top of your bin there is a good chance they would be covered in mold in no time. In a well balanced system on the other hand, the worms and other bin creatures will keep excess fungal growth in check.

It might not be a bade idea to add a layer of fresh, dry bedding over top of the materials in your bin – this helps to keep the microbial growth down below where it belongs.

Hope this helps!


[tags]fungi, worm bin, worm composting, vermicomposting, mycelium, food waste, ecosystem, bacteria, microorganisms[/tags]

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In-ground Worm Bins

Looks like today is going to be another busy ‘Reader Questions’ day. I’ve been getting some really good ones lately and have been enjoying answering them here! This first ‘question’ (which isn’t really a question) comes from Felicia. She has an interesting idea for keeping her bin warm/cool and I thought others might benefit from her creativity.

I would like to start out with European Nightcrawlers in
hopes of raising worms for fishing as well a composting. Today, I
started a plastic bin (10 gallon) with moist peat moss and a small
portion of, coffee grounds, and onion and potato peelings. Since I
live on the outer banks of North Carolina, and it turned cool again
today, I sunk the bin in the sand under my home about 3/4 of the way
up in hopes that it will keep the bin warm in the cool weather and
cool in the warm weather. I added to that about 8 worms from my
garden just to try it out. I have since read your recommendations
against yard worms.

Hi Felicia,
I’ll often recommend in-ground worm bins as a way to help keep worms warmer during colder months, and you are absolutely right – the opposite effect can expected in hot weather. The earth is an excellent insulator and isn’t affected by rapid air temperature changes. Keep the bin under your home is also a great idea since it will provide even more shelter during hot/cold periods.

I especially like your idea since you can pull out the entire bin when you want to harvest castings (although, it will certainly be very heavy) – whereas a truly in-ground system would be quite difficult to work with, assuming you ever wanted to remove worms and/or worm castings.

If your area gets especially cold during winter months you may need to take some extra steps to protect your worms from the cold. You may need a larger system to help generate (and hold) more microbial heat, you may need to sink it further down into the ground, and you might also want to add a thick layer of insulation over top (straw, leaves etc work well).

For your particular bin (the one you described above) I would recommend adding more food waste, and also mixing in some shredded cardboard or newsprint. Peat moss is a good bedding material, but you’ll get better air flow if you also add some other bulkier materials. When first starting a bin you can definitely get away with adding more food scraps – assuming you then leave the bin for awhile before adding your worms. This allows time for lots of microorganisms to colonize the materials and for moisture levels to balance out.

You are right about the garden/yard worms – I definitely don’t recommend adding them to a vermicompost bin. If you system is in direct contact with the soil (i.e. isn’t sealed) plenty of regular earthworms will venture into the lower regions to feed on organic matter, but you won’t find an abundance of them up where the composting worms are. Most regular soil dwelling worms require cooler, less crowded conditions in order to thrive. The worms you added may survive for quite some time, but the chances of them reproducing (assuming they are even the same variety) is slim to none.



[tags]worm bin, composter, worm composter, outdoor worm bin, vermicomposting, worm composting, composting worms, earthworms, earth worms, european nightcrawlers, composting[/tags]

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Squash Vermicomposting

Way back in the fall I mentioned that I was going to be making a “squash decomposition” video. Well, I DID set up the experiment and take a bunch of photos, but alas I just didn’t have the time to make any more powerpoint videos at the time, so it (and other planned videos) got put on the backburner for the time being.

I came across the folder of all the images last week and decided once and for all to get the video put together. It did take awhile but I’m definitely glad I finally made it – I think it’s kinda fun! Hopefully it will help to make more people want to compost with worms. To some, 47 days may seem like a long time to compost a few pieces of squash, but do keep in mind the fact that fresh squash is actually quite hard and resistant, and there was also a lot of shredded cardboard in there that was processed as well.

At some point I want to post the actual photos somewhere on the website so you can see them up close and personal. There seemed to be some interesting things taking place. At one point it looked like my worms were trying to high-tail it out of the bin – I suspect that the decomposing squash was giving off some sort of unpleasant gas that was irritating the worms. Whatever it was, they seemed to settle down within a day or two.

As you’ll see I wasn’t able to capture every single day during the experiment. I went away for Thanksgiving (a trip that ended up being extended unexpectedly) and simply forgot at other times.

Anyway, hope you like it!

Next on the agenda is vermicompost harvesting. It goes hand in hand with a new project I’ve recently started so I’ll likely be able to get to that this week or next.

[tags]composting, compost, squash, decomposition, rotting, decay, vermicomposting, worm composting, red worms, red wigglers[/tags]

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28 Worm Experiment

Young European Nightcrawlers
Young European Nightcrawlers (Eisenia hortensis) at various stages of development.

Inspired by my ‘Four Worm Experiment‘, one of our loyal readers, Alicia P., decided to try out her own small experiment. Instead of four Red Worms however, she opted for 28 European Nightcrawlers. Here are the results she shared with me today (and gave me permission to post here).

On 2/3/08 I started this bin with 28 adult Eisenia
worms, all the EHs from my “wild” worm bin (in case you were
wondering if there was significance to the number 28. There isn’t!).

On 2/14 I poked around, eager to see if the EHs were reproducing. They
were! I found 60 cocoons at that time– just 11 days from start-up.

Today (3/27/08), just shy of 2 months, I went through my bin and was
delighted with what I found. Realize that the numbers of cocoons and
hatchlings is surely under-representative of the actual numbers. I find
that the hatchling EHs are much, much more difficult to spot that
hatchling EFs. Maybe it’s just me. Anyway, I know quite a few managed to
get past my searching. I’m putting the VC from the EH bin into its own
storage container. In 6 weeks or so, I’ll check it and see what I find.
I’m sure I’ll find juveniles and some babies.

So, today’s results:

Adults: 25 (I have no idea what happened to
3 of them)
Cocoons: 148 (This is not counting old, hatched
cocoons, of course, just currently viable cocoons)
Hatchlings & Juveniles: 251

I’ve read that EHs are slower reproducers than EFs, but my own small
experiment has not proven this true. When I compare the production of my
EF breeder box with this EH bin, they are tied at least in cocoon
production. The EF may have an edge on number of hatchlings per cocoon.
I am not curious enough to try to calculate that– that would require
too much time & effort for my schedule.

Anyway, I’m excited about this. It looks like by summer’s end I’ll have
a nice, thriving EH collection. Online, most places site 250-300 EHs per
pound. I should easily have a pound of EH by then, after starting with
just 29 adults.

You have EHs, Bentley. I’d sure love to have you reproduce my 29-EH bin
and see what results you get. It would be quite interesting to compare
our results. Any chance I could talk you into it? FWIW, my 29 are in a
3-gallon Rubbermaid container.

As I told Alicia, her observation and reporting skills certainly put me to shame (when compared to my reporting thus far for the ‘Four Worm Experiment’). haha!

As far as Euro reproduction goes, I too have been pleasantly surprised by how readily and quickly they seem to produce offspring. I think we’re going to have to put Euros and Reds head-to-head this year so we can really figure out if there is any validity to the ‘slow reproduction’ etc claims in the literature!

Thanks again to Alicia for sharing her results. If anyone else has been doing different worm-related experiments be sure to let me know!

[tags]worm reprduction, red worms, red wigglers, european nightcrawlers, eisenia fetida, eisenia hortensis[/tags]

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Bokashi Vermicomposting

Bokashi 'Compost' Added to Worm Bin

As some of you may know, for the last couple months I have been experimenting with another waste management strategy called ‘bokashi’. I’ve been writing about it over on the CompostGuy Blog (you may also want to check out the Compost Guy Bokashi resource page).

For those of you unfamiliar, bokashi is a very simple way to deal with common household (organic) wastes. All you need is a bucket (although a specialized bokashi bucket works best), some bokashi mix, and some food waste. You then add your scraps to the bucket and sprinkle some bokashi mix at the same time. When the material reaches the top of the bucket you put on the lid (which should always be on when not adding scraps) and let it sit for a few weeks. The final product can then be dug into your garden or added to your compost bins. The bokashi mix itself is wheat bran impregnated with special microorganisms. You can buy this mix or make it yourself, which can actually be a lot of fun.

Unlike vermicomposting and composting, bokashi is an anaerobic process, but interestingly enough it doesn’t smell bad thanks to the bokashi mix microorganisms. Also unlike regular aerobic composting, you don’t actually end up with a stabilized, humus-rich material. The end materials need to undergo further decomposition in order to become an effective plant fertilizer and soil conditioner. Nevertheless, given the simplicity of the process I think it’s a great option for a lot of people – anyone with a garden or compost bins, that is – I wouldn’t recommend this for apartment dwellers, unless they happened to have a big balcony garden and/or some worm bins.

Part of the reason I was attracted to bokashi (aside from being such a composting fanatic) was because I suspected that the end product would make an excellent ‘worm food’. I commonly recommend that people keep their food scraps in a separate container for a little while so as to allow time for microbial colonization. Well this method does just that, and the final product is absolutely loaded with microbes – and once it is exposed to aerobic conditions it likely becomes an even richer microbial playground.

Two of my bokashi buckets have been brewing for a number of weeks now so I decided it was finally time to try feeding some of this stuff to my worms. As you can see above, I put a decent layer of material at the top of my European Nightcrawler bin. I made sure to add some dry bedding first, just to help separate it from the worms a little should they not feel like moving into it right away. I’ve read that worms go crazy for the stuff, so I’ll be interested to see what happens.

I’ll keep you posted!

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How Much is Enough?

A couple great questions from Robyn this evening…

Hi Bentley,
I am brand new to this and very interested. I’ve already begun collecting kitchen scraps and have been reading through your articles. Perhaps I haven’t come upon the right article but some questions that I have now are:

1) you mention a “decent amount” of food scraps to bedding…what would this be — equal amounts? more food scraps than bedding? And also, are these layered or mixed together?

2) How does one know when the compost is “ready”? In other words when is it ready to put on the houseplants? Also, is this kind of compost ok for container gardening, specifically a tomato plant?

Hi Robyn,
I’m glad you asked these questions because I have little doubt that there are others wondering the same thing! Ok, let’s get to it.

1) I know I tend to be rather vague at times – aside from being the sort of person that just kind of ‘wings it’ a lot of the time, I also really feel strongly about the idea that there are no hard and fast rules for these sorts of things. Every worm composting system is different (there are so many variables involved) so I always recommend that people test these things out for themselves.

That being said, I’m not just going to leave you leave you hanging like that. 😆
I would definitely say the amount of food (volume, that is) you add should be less than the amount of bedding added. [NOTE: Just in case anyone is unsure, I should mention that we are talking here about when you start up a new bin (before worms added) NOT when you are adding materials once your worms are in the system.] Remember that the bedding serves as a protective buffer for your system, absorbing excess moisture and helping to keep the overall C:N ratio in a safe zone (if it gets too low, nitrogen tends to be lost as ammonia gas which can harm your worms). I would still recommend adding a large volume of food scraps though – perhaps 1/2 the volume of the bedding. As for mixing or layering – either/or is fine (I’ve done both), but DO make sure there is a layer of pure bedding material at the bottom since this is where the most moisture will tend to accumulate.

[Update – Mar 26/08: I started a new worm bin today and realized that the amount of food scraps I feel comfortable adding is actually closer to the volume of the bedding than I thought – perhaps 3/4. I used a layering system today – 4 layers of bedding (1st and last – nice and thick), and 3 layers of food scraps]

2) This is another example of something for which there are no hard and fast rules. If you are using some sort of flow-through system it is much easier to know when the material is ready since the worms are continually moving towards the zone with the best food resources, leaving the compost material behind. In the case of a stackable system like the ‘Can O Worms’, the idea is that once your last (upper) tray has been added and fills up, the compost in the lowest tray is probably ready to be used.

In the case of a regular worm bin (a plastic tub, for example) it can be a little bit more of a challenge to know when you can start harvesting. My recommendation is to simply wait until a lot of the material in the bin has a dark, soil-like appearance, with no residual food waste or bedding. If your system is sealed (i.e. no drainage holes), the material near the bottom will likely be quite anaerobic (oxygen deprived) and definitely shouldn’t be used right away. I’d suggest dumping out your bin (preferably on a sheet or mat outside) and breaking up the compost with a garden fork, then leaving it to dry out somewhat. The worms will concentrate down below and the compost can gradually be removed until you are left with partially digested materials (and worms), which can be added to a new system (something you should prepare prior to harvesting.

As for worm castings (vermicompost) being used in container gardening – ABSOLUTELY! The beauty of this type of compost is that a little goes a long way. A small handful placed in the hole when you plant each tomato should make a big difference.

Anyway – hope this helps!


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