Saturday, March 27, 2010

How to make an indoor composter for $10

Want to know how to compost indoors? Here's are the details for the composter I made for my kitchen out of a couple of totes. Best of all, it'll only set you back $10.                                                    

AUTHOR'S NOTE: This is part 2 of 2 in a series of posts on indoor composting. Click here for part 1.

I previously posted on the specific challenges of composting indoors, and from that, I decided to make an experiment out of composting indoors.

Well, I've built my composting bin and it's been going for about a week now.

Here's how:

Find a couple of matching plastic totes. These are 18 gallon bins. That is a bit excessive, but they were on sale for $5 each, which made them cheaper than the 10 gallon bins. If you have old bins, or can find used bins, choose those over buying bins... but remember that they need to have lids.

Drill holes in the bottom of both totes. The holes should be a quarter inch to allow the eventual migration of worms from one bin to the other (did I mention there were worms involved?) My dremel only had bits up to 1/8" so I improvise and used a grinding stone to widen out the holes.

The next step was to repeat the process, adding 1/16" holes around the top of the bins and in one of the lids.

It's probably hard to see since 1/16" holes aren't that big, but there are two rows of holes, about an inch apart, all the way around the bin.

The same with the lid. Only one of the lids though! We'll be using the other one for something else.

Soak enough shredded newspaper and scrap paper to fill the bottom 3-4 inches of the bin. Wring it out so that it's moist but not dripping. Add some vegetable matter to this. Make sure you bury the vegetable matter to keep fruit flies out of it. Let this set for a week or so before you add worms so the food can start breaking down.

Get your worms. If you have red wigglers growing wild in your area, you could just dig some up. I don't, however. Don't use night crawlers. Red wigglers are surface feeding worms that do well in big groups. Night crawlers feed deeper in the soil and are loners. They're not a good choice for a composting bin. 

I ordered my worms from It wasn't the best experience in the world (they sent the wrong shipping confirmation, I had no idea when the worms were supposed to be arriving, worms looked half-dead when I got them). But, this was one of the few places I found where I could place an order for just a 1/4 pound of worms. It only cost $11 plus shipping, and I was looking to start this bin as cheaply as possible. And they all ended up living, so despite the less-than-stellar service, I can't complain.

Add them to the bin! Along with a cupful of dirt, of course. The dirt helps them grind up food, and contains microorganisms to break down food scraps.

Somehow I neglected to take a picture of the completed bin all set up. I'll have to do that at some point. Here's what you do:

Set the lid without the holes on the floor. Rescue four or five paper cups and place them upside down on the lid (I used a glue stick to hold them in place). Set the bin with the bedding material and worms on the cups. Place a piece of cardboard over the bedding. Place the second bin inside the first. And then put the lid with holes on top of the second bin.

When the first bin is full, add moist bedding and food to the second bin and remove the cardboard from the first. This will allow the worms to move into the second bin and start the process all over. Once the worms have all moved into the second bin you can empty out your delicious compost and use it on your plants.

A couple of important things: keep your food scraps covered or you will end up with a fruit fly infestation. Guaranteed. Also, don't feed your worms more than they can eat or it will start to smell. Red wigglers can eat half their weight in a day. That means my small 1/4 pound of worms can eat about a pound a week.

As things start to break down, I'll be watching for odors. If things get out of hand, I'll test the carbon filter theory.

AUTHOR'S NOTE: This is part 2 of 2 in a series of posts on indoor composting. Click here for part 1.

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