What do I need to know before I start vermicomposting?

March 8, 2006 5:04 PM

What do I need to know before I start vermicomposting (a là Woms Eat My Garbage)?

I cook for a household of three and am starting a kitchen garden. I'd like to set up a worm bin, both to eat up some of our kitchen waste and give us free worm castings for fertilizer.

What should I know first? What pitfalls should I avoid? What books (other than the aforementioned W.E.M.G.) should I read? What online sources are worth checking out?

posted by nebulawindphone to home & garden (8 comments total)

Your wormfarm should be out of the sun but not too cold. I think they hibernate in the winter when it gets too cold (like snow on the ground) but they generally survive.

Worms don't eat citrus peel or onion skins. generally they wont get enough carbon from kitchen scraps - some grass clippings or cardboard is also necessary.

A properly operating farm shouldn't smell, bit it might, and it'll likely attract little fruit flies, so while it's good to have it close to the kitchen, not too close, at least until you know it's healthy.

It will take a long time for the population to build up, maybe a year, especially if anything goes wrong, so don't over feed them to begin.

The worm wee is good liquid fertiliser. Not some miracle juice like some believe, but good for the plants - quite a bit can be created, so have a dsposal plan (tipping it downt eh drain would be a waste).

Have fun!
posted by wilful at 5:17 PM on March 8, 2006

Here's a beginner's guide to vermicomposting. The purchasing information is Ontario focussed, but the guide information may be useful.

http://www.greenventure.ca/gv.asp?ID=133
posted by Cyrie at 7:46 PM on March 8, 2006

Don't try to make a farm - it's easier to buy one from the local garden centre (and it'll be higher quality too). Go for one of the stackable ones so you can easily shift your worms from bin to bin and make use of their castings.

Buy a farm which is on wheels, or to which you can attach wheels - you'll find yourself moving that sucker around a bit, and it's way too heavy for one person to lift when you have three bins stacked on top of each other.

The tiny golden semi-translucent spheres? They're worm eggs. If you see these in your compost your worms are doing well.
posted by Ritchie at 8:00 PM on March 8, 2006

I've played with lots of ways to do this, and I'm happiest with what I currently do.

First, the outdoor part:

1. Get hold of four old car tyres (low profile fats, preferably - mine are 245/45R17's). Tyre service centres have big stacks of dead tyres out the back and will be only too happy to see you take some away (they cost the business about $3 each to recycle).

2. Dig two round, flat holes a little less than one tyre deep and a little wider than one tyre wide, sit a tyre in each, and backfill around the outside. You should end up with about 20mm of tread visible above ground level.

3. Sit a second tyre on top of each sunken one.

4. Make round plywood lids (I used hoarding ply scrounged from a building-site dumpster) to fit the rim indentation of the top tyres. Paint the lids white. Sit them in the tops of the tyres and hold them down with a brick each.

5. If your stacks are placed where they'll get afternoon sun, paint the top tyres white as well.

6. Get about 500g of composting worms (reds, blues and tigers) from a reputable supplier. Put them inside the rim of one of the top tyres, with enough spent mushroom compost or rich potting mix spread around the rim to cover them completely. That will keep the worms going until your food scraps start rotting down enough to be scrumptious.

7. Spread the same compost mix around the inside rim of the other top tyre, but don't put any worms in that one.

Now the indoor part:

1. Get an old cafeteria food tray or similar, and keep it on a kitchen bench with about 8-10 thicknesses of newspaper on it. Pile up your scraps on that. Don't worry about separating out citrus and onions - the worms will eventually eat them, even if several other things have to eat them first.

2. At the end of each day, before the mice come out to play, slide the scrap pile (and its underlying newspaper) off the tray onto two thicknesses of broadsheet newspaper, and wrap the whole lot up into a tight parcel. If your tray has a damp spot, wipe it down and use more newspaper in step 1 next time.

3. Put the whole parcel, wrapping and all, into the bottom tyre of the stack that has the worms in the top.

4. Once you've added enough parcels to fill the sunken tyre (probably at least a month), you're ready to start feeding the second stack. Swap the top tyres, so the wormless one ends up over the parcels (which will by now be crawling with worms) and the wormy one ends up over the empty sunken tyre.

5. By the time you've filled up the second sunken tyre, you'll find there's now plenty of room in the first one to start feeding that again. You don't have to switch the top tyres again, just keep stuffing parcels into whichever stack has more room. You can pile parcels up in the middle until they're just under the plywood lid, but don't sit any inside the rim of a top tyre; if it looks like you need to, make a third stack. You probably won't need to do this (two stacks have dealt with all the scraps from our three-person household for the last year and a half and show no signs of clogging).

6. Whenever you use your vacuum cleaner, empty the dustbag into one of the tyre stacks. Worms love that stuff, and a bit of grit aids their digestion. Dog turds are fine too.

How it works:

Piling scraps on a lined tray in the open, instead of stuffing them into the customary covered bucket, means they don't rot and smell bad in your kitchen, don't attract vinegar flies, and don't create a slimy nasty bucket-washing requirement. If you have lots of meaty scraps and a housecat, you'll need to make some arrangement to restrict access (I use a wire basket upside down over the tray).

The newspaper balances up the food scraps' sogginess and nitrogen content. By adjusting the thickness of the newspaper tray lining until your tray no longer gets damp, you not only save needing to wipe down the tray, you maintain a pretty good C-N balance without having to think about it.

Once inside the tyres, the layers of paper in the parcels provide an absolutely ideal breeding environment for the worms. They'll also breed up happily inside the rims of the top tyres, as well as just spending time there (which is why all you need to do to establish a new stack is move over the top tyre from an existing, active stack).

Tightly wrapped parcels, when piled up inside the tyre, have enough air spaces between them to keep the rotting process working aerobically (non-stinkily) and the feeding worms healthy. There are enough air leaks between the two tyres, and between the tyres and their plywood lids, to supply the needs of the creatures inside.

The castings from the composting worms are ideal food for your local earthworms, which will visit the underneath of the sunken tyres to get at them. This means you don't ever have to empty anything out. If you put these tyre stacks in your vegie garden (one in the middle of each raised bed works really well) they act as "mouths" for the whole garden; the composting worms eat your scraps, and roving earthworms share the love throughout the bed. If you put one in a lawn, you'll see a spreading ring of noticeably healthier grass around it after just a few months.

The sunken tyres are far enough underground to discourage the ingress of roots (even if they're sitting right in the middle of your lawn) and mice.

The plywood lids with bricks also keep out mice (though I've occasionally found skinks and small frogs inside my stacks).

The air inside the top tyres can get quite warm in the sun, which tends to "cook" anything that sprouts inside the stack. The temperature in the bottom of the parcel region, where your worms are mostly feeding, stays pretty stable.

Finally, none of the required materials costs money (except the worms).

Other things I've tried that my tyre stacks work better than:
- Gedye compost bins (too big, not enough ventilation makes them go stinky, root ingress problems)
- Lightweight rectangular recycled plastic compost bins (too much ventilation; worms die from overdrying, flies gain access through vent holes)
- Stacked-tray worm farms (fiddly, heavy and messy to rearrange active trays as they fill; requirement to tap off the liquid vermicast from the bottom tray every day, lest you end up with a stinking maggoty pool of drowned worms)
- Wooden worm farms with scraper floors (scrapers clog and stick, scraping action kills worms)
- Large open compost heaps (mice, mice, mice!)
posted by flabdablet at 2:24 AM on March 9, 2006 [1 favorite]

Interesting system, flabdablet. Is the idea for the tires to provide insulation? Because the ground definitely freezes where I'm at.

Also — if you were setting up a stack of tires in a raised garden bed, how deep would you dig in the lowest tire? Just a little ways into the bed? Or down through the bed and into the ground below?
posted by nebulawindphone at 6:09 AM on March 9, 2006

The tyres will insulate to a certain extent, but not much. It doesn't snow where I am, and though we get some pretty hard frosts in winter, the ground doesn't stay frozen.

The main reasons for digging the bottom tyre in are (a) to surround it with earth, thereby stabilizing the interior temperature (b) to discourage ingress of roots, grass runners and mice.

In a raised garden bed, I'd still only use two (fat) tyres in a stack, and dig the bottom one in such that only a little bit of it protruded above the soil. If you have tyre-to-tyre junctions below ground level, roots will surely find their way in and clog up your works. You also don't want the bottom of the whole thing so deep that earthworms (the garden's circulatory system, as opposed to composting worms - its digestive system) won't find it.

The rot process itself does generate a certain amount of warmth. You might be able to keep your critters from freezing in winter just by piling a heap of straw or other mulch all around the top tyre (this might also be a good way to keep the sun off in summer). You could also try making your plywood lids white on one side and black on the other, and using the lids black-side-up in winter.

If your worms do slow down in winter to the point where they're not keeping up with your kitchen scrap production, just add a second stack next to each existing one. Compost worms will migrate from one stack to the other through the tunnels that the earthworms dig.

Incidentally: when I originally set these things up, I'd intended to use the bottom (dug-in) tyres as mini garden beds for gross feeding crops (pumpkin, zucchini, corn etc) after they had filled up with vermicast; but so far, they're just not filling up. Maybe in a couple more years :)
posted by flabdablet at 7:03 AM on March 9, 2006

Check out the woman who did much to start hoome vermicomposting's popularity: Mary Appelhof
posted by RelentlesslyOptimistic at 8:35 AM on March 9, 2006

One thing to add to all the great advise above....
Your first night or so the worms are not moved in and may try to escape. I set my bin up by the back door so i could leave on the light, this will keep them from escaping. It is also very bizarre looking, these worms squeezing out of the holes then retreating from the light. i did it for two nights and then they were happy. Your worms may be a different type ymmv.
posted by blink_left at 10:20 AM on March 9, 2006