The Smallest Worm Bin

Worm Composting in a Tiny Space

Most worm composting bins take up too much space to be practical in a tiny home.  But adding a worm bin to your space can make your life much easier.

  • Less trash
  • Trash doesn't smell as bad
  • Free compost!
  • Ability to tell people you're keeping livestock in your tiny house.

Worm bins don't need to be big or heavy.  With a little modification, you can build your own tiny worm bin that fits inside a kitchen cabinet.

In this article, we'll review a case study of a tiny worm bin installed in our 27' Airstream Overlander, where we live full-time.

tiny flow-through worm bin installed in an Airstream RV for full time living
Tiny Worm Bin

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How to Build a Tiny Worm Bin

The trick to building a successful worm bin is airflow and drainage.  If you can keep air flowing and moisture draining, your worms will be happy no matter how small their bin is.

The most popular commercial worm bin uses a stack of trays that you need to manually cycle once in a while.  I say, let the worms do it.

Suspend a minnow net inside a small kitchen trash can, and you've got an ideal composting system.  A minnow net has holes large enough to let the worms and their castings past through, but large enough to keep the scraps and bedding inside.  Find one made of a synthetic material so the worms don't eat it.

Add a drain and a screened false bottom to separate the water from the castings.  A tight-fitting lid on top with no-see-um screen keeps the worms from escaping and allows plenty of airflow.  (Worms can crawl straight through regular window screen.  Ask me how I know.)

worm net from a tiny flow-through worm bin, removed for separating worm castings
Tiny Worm Bin Netting

How to Maintain a Worm Bin

Our 1,000 red wiggler worms do a great job at keeping up with all our vegetable scraps.  We're only two people, but we cook at home all the time and eat a lot of fruits and veggies.  If you don't have enough worms at first, don't worry.  They'll adjust their own numbers to match their food supply fairly quickly.

We keep our bag of scraps in the freezer to soften them up and keep pests to a minimum.  We feed the worms every day or two, drain water from the bin once every couple of weeks, and harvest the castings around once a month.

To harvest, I take the entire bin outside and pull out the net.  I dig the castings out of the bin with my hand and put them in a bin.  There's a lot of worms hanging out in the castings, so I sit in the sun to separate them.  As I slowly remove the top layer of castings from the pile, the worms will keep digging deeper until all that's left is a pile of worms.  Worms go back in the bin, and we're good for another month.

What to do with the castings?  Well, they're great for gardening.  But since we don't have a garden of our own, we use them to make seed bombs.  I'll collect as many native wildflower seeds as I can find, mix them with the worm castings, and form them into balls.  Toss the balls in neglected roadside ditches, and leave the world a little nicer than you found it.

separating worm castings in a bin using sunlight
Separating Worm Castings

Check out the full worm bin build and all the details here.

Dealing With Mites and Other Pests

Mites will inevitably colonize your worm bin.  There are lots of tips to remove them, none of which work very well.  Freezing scraps before putting them in your bin may help kill mites, but it's not foolproof.

Fact is, mites contribute to composting, and don't really hurt anything.  In a shallow bin, the mites might irritate your worms.  But in a deeper bin like the one described above, the mites tend to stay on top and the worms live below.  Even if your worms are getting bitten, they'll be fine.

You might also get other uninvited guests like black soldier flies or fruit flies.  Freezing your scraps before you put them in the bin can help kill off eggs and larvae, but again it's not foolproof.  Keep a screen with no-see-um netting on top of your bin to keep any flying critters contained.

Black soldier flies look mean, but they're totally harmless, and their larvae contribute to your composting.  In fact, black soldier fly composting is another popular method to compost food waste.

wildflower seed bombs made from worm castings
Wildflower Seed Bombs

Author: Dan Greatley