Wednesday, February 22, 2006

Can-O-Worms Update

I finally feel like I've got the hang of this whole kitchen vermicomposting thing. The first few months require patience because you put your worms in their bedding (I used coir), which they slooooowly eat, and then you start feeding them their preferred diet of veggie scraps, coffee grounds, banana peels and more until you've got a layer of finished compost. Once you're up and running, you have three layers going at the same time. The top layer is for fresh scraps and the two lower layers are still full of worms, but are further along.

When you want to use the bottom layer of finished compost, you move it to the top and remove the lid. In a day or two, the light and air drives the worms into your covered "fresh" layer below so what you end up with is pure compost ready to use in the garden.

It's so great to empty out the crisper bin of the fridge knowing that unused veggies aren't a total waste. Ok, so we ignored that broccoli or that bag of mixed baby greens. All is not lost! It's compost!

One temporary nuisance was the arrival of fruit flies. Opening the bin felt like I'd been visited by a plague of very tiny locusts. Luckily, the fruit flies don't adversely affect the worms or the compost. They're just annoying little... annoyances. Rotating the bin layers helps, as does adding a layer of bedding on top of the freshest kitchen scraps. If things get desperate, Gardener's Supply sells a fruit fry trap. A much more economical solution is to make your own trap using the excellent online instructions by Dr. Vett Lloyd, Department of Biology, Mount Allison University in New Brunswick, Canada.

(March 6 update-- I've been revisited by fruit flies and lept at the chance to make my own traps. Guess what? They work great! I put one on the counter near the bin and one in the bin. Both traps, using both designs shown in the above link, are filled with dead fruit flies in just two days! All it cost me was a little cider vinegar. I tried covering my scraps, but the flies kept hatching. Thank you, Dr. Lloyd!)

Overall, I've been very happy with my kitchen vermicomposting experience and plan to continue it indefinitely. Worms really are eating my garbage and giving me this amazing garden compost in return.


  1. Anonymous9:27 AM

    What I use to keep fruit flies out of my COW is shredded paper--either shredded computer paper or newspaper I tear into strips. Just keep a good thick layer on top and bury the food under it--the flies don't seem to find it that way. The shredded paper is also good for soaking up excess moisture, or if it's too dry in the bin, like in the summer, you can drop a couple ice cubes into the paper and let them slowly melt--the paper kind of holds onto the moisture and releases it slowly so you don't flood the bin.

    good luck--


  2. Thanks, Amy! It's always nice to get advice from a worm guru such as yourself.

  3. I don't have a COW but I do have two homemade 18 gallon Rubbermaid contraptions downstairs in the basement. Occasionally the fruit flies invade, and like anonymous I use shredded paper, newspaper usally. A $10 shredder from the store does wonders there. I've read that it also helps to bury the fresh fruit/veggie stuff or stick it in the micro or freezer prior to feeding. Not wanting to smell nuked rotting veggies/fruit and also not willing to give up the freezer space, I opt with the burial/newspaper route.

  4. Thanks, Kerry!

    Now you and Amy have me wondering about newspaper inks. I've always heard you shouldn't use colored inks in the garden, but are the black inks considered safe? In other words, what's in the ink?

    I'd like to get a shredder and try using newspaper. I just have that one little reservation and need to do a little research.

    Thanks also for the freezing/nuking tip! I may try both.

  5. Angela,

    From what I have read 'most' newspapers have gone to soy based inks. That being said, if you have any doubts perhaps a call to your local paper might give you some insight into what kind of inks they use. I've only had my bin for about a year so I am no expert by any means but the worms are lovin' it so far. I don't shred the glossy ads but everything else in the newspaper (including the comics) is fair game. When I set up a bin the bedding consists of pre-wetted newspaper shreddings plus a little bit of casings mixed in to innoculate the paper with the microcritters that help break it down for the worms. As I feed them I cover with more paper, dry if the bin is on the overly moist side, wet if it could use some moisture.

  6. Interesting. I need to contact my local paper.

    Found this interesting thread on Google:

    "And here's what the "Master Composter" site has to say:"

    "With regard to composting newspapers with black ink, I have only
    heard one mention of controversy. Otherwise, I have found that
    composting newspapers is acceptable. (As mentioned above, it is not
    usually recommended for use in a backyard pile because of the problems
    of matting, low nutrient value and slow decomposition.) The one
    controversial source was the book "Let It Rot" by Stu Campbell. He
    says that the carbon black ink contains polycyclicaromatic
    hydrocarbons (PAH) which are a known carcinogen. Stu says

    "Although the jury is still out, most scientific research to date
    indicates that PAHs are rendered inert by the temperatures of a hot
    compost pile, the biological activity, and the acids in the soil. Most
    newspaper inks no longer contain heavy metals, and most colored
    newsprint now uses vegetable dyes, so as long as you don't intensively
    compost with newspapers you can use it as a carbon source."

    "With regard to newspapers, A Green Guide to Yard Care published by
    the Texas Natural Resource Conservation Commission says, "Most inks
    today are safe for garden use." To be completely safe, call your
    newspaper and ask about the ink or use compost made from newspapers on
    non-edibles like your lawn, ornamentals, flowers, and trees, rather
    than your vegetable garden.

    "Do NOT compost advertising inserts. Ad inserts are printed by someone
    other than the newspaper. Most companies still print inserts with
    heavy metal inks, especially the glossy ones. Some colored inks have
    heavy metals in them which, in large quantities, are toxic to
    microorganisms. Small quantities such as the occasional colored ad in
    the newspaper have negligible effects.

    "With society's emphasis on recycling, most newspapers have started
    using vegetable dyes for colored advertisements and the comics. (If
    your newspaper uses vegetable dyes, you can compost the comics, too.)
    Unfortunately, there is no way to be certain which dye they use by
    looking at the printed page. To make sure, call your local newspaper
    and ask them if they use vegetable dyes."

  7. A couple of questions about the COW. How often do you harvest a tray and how much does it hold? Do you find that by the time the tray is ready to harvest that it is free of worms?

    I am intrigued by the idea of easy harvest. I harvested one of my bins earlier this week and while I got a 5 gallon bucket of castings it was a major pain picking the worms out of the mix. A plastic tarp, a pile of worm stuff on the floor and about an hour and a half was involved.

  8. Hi Kerry,

    I haven't actually measured my compost yield, but I can tell you that it'll take all the scraps a family of three put out.

    From the size of the COW, it looks like all three layers would fill a 5-gallon bucket. That's just a guess and I'd check the manufacturer's website for capacity.

    Because vermicomposting takes time, I tend to forget about harvesting. I just keep feeding the worms my scraps. Then a couple months (2? 3?) pass and I think, "Hey, I'll bet that compost is ready!"

    So far I haven't had to replace my worms. I keep the COW in my kitchen, so the bin doesn't get too hot or too cold, too wet or too dry. The design of the COW is very clever in that you can drain any excess liquid and the separate bins with holes allow for worm migration before you harvest. I don't think I'd have the patience to sift out all my worms at harvest time. I pick out a few stragglers (3-10) but compared to how many worms are in there to begin with, it's no big deal.

    I thought about making my own bin, but the design of the COW seemed so clever and self-contained, and it is.