Building a Worm Farm

Worm farms can be built out of whatever you have handy…tupperware bins are easy, you can use nested kitty litter buckets, wooden crates, old refrigerators, or 4 straw bales (for an outdoor system).  In addition to my homemade bins, I buy vertical composting systems (e.g., Wormtopia, CanOWorms), too, great for teaching purposes and increasing the colony size and castings.

Basic worm bin:  2 tupperware bins.  The inside one, you drill ½” holes throughout the bottom (maybe 20 holes?) for the worm leachate to drain into the bottom reservoir.  Drill similar holes to the lid of one bin.  The other lid is extra, I keep mine around in case I’d need to use the non-drilled Rubbermaid for something else in the future.  (Note: worm leachate is the stuff draining if you were to dampen your bin/water it slightly.  This could become worm tea if you brew (aerate) it for ~24hr (can add mycorizal fungi, molasses, kelp).

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I put wet/damp newspaper in the bottom of bin, right over the holes you drilled.  This will let the bin drain but will also keep the worms from dropping into the reservoir bin below.  The newspaper eventually decomposes and you can re-do in a year or so. If you desire, you can add a spout to the lower reservior so the leachate drains but it is not really neccessary.   IMG_8074

Worms need bedding that is composed of mainly Carbon– this can be shredded newspaper (I just hand shred), brown paperboard, paper egg cartons ripped up, coconut coir, dried leaves, peat moss.  The worms live in the bedding and also reproduce in the bedding so keep plenty on hand! The carbonous bedding is important in the C:N ratio of decompostion.  More bedding (C-rich) than food scraps (high in N) is a good rule to follow.  Water it until it’s damp like a wrung-out sponge. If you use chlorinated tap water, let the Cl disapate for a few hours before adding to your farm.  I don’t recommend shredded office paper.  I use office paper outside in garden beds but not in this enclosed small system; dioxin/bleach leaching isn’t good for worms.  Make a habit of collecting every free newspaper you see, your worms will thank you.

After the shredded paper is in your bin, you can add your worm starter.  A starter is a small container of Red Wrigglers (Eisenia fetida) for free from a friend (me) or that you buy online (Craigslist is great), and other websites will charge around $25 for a pound of worms mailed to your house.  Worms do not have teeth, they only ingest  food that they can swallow (they have very small mouths!) and require sand to grind their food, similar to a bird’s gizzard.  Add a ‘spash’ of sand or outdoor soil for worm grit.

Earthworms like night crawlers do not survive in small systems like this.  They are large-area soilworkers and require more space.  Red wrigglers are composting or manure worms, they live in the top 30 cm of soil, usually in compost piles which is why they do so well in an indoor system.

  • Red wigglers are tropical, 40-80 degrees F is optimal.  Too cold, they will freeze and die, too chilly, metabolism slows down and they will eat less, reproduce less.  Too Hot – same thing.
  • Red Wrigglers can eat 0.75-1 pound of their weight daily.  Basically, if you have a pound of worms, they will eat almost a pound of kitchen scraps everyday, the world’s best recyclers!  You may not have a pound when you start but by month 3-5, you prob will.
  • Adding Cabon (shredded paper) every month is just as important as the nitrogenous food materials that you add regularily.  A general compost ratio to follow is 30:1, for every 30 parts carbon, 1 part nitrogen is needed for microorganisms to break it down.
  • Red Wrigglers will become sexually mature around 60 days.  These hermaphroditic organisms will ‘drop’ cocoons ever 7 to 10 days with each cocoon have up to 20 worms inside.  Because they are hermaphroditic (male and female), their population increases exponentially.  For example, if you start with 1# or ~1,000 individuals, your popualtion will double every month under optimal environmental conditions. Ask me about worm sex, that’s pretty interesting, too.
  • Another note, worms are annelids or an animal phyla of segmented worms.  But this does not mean you can cut them in half like planarians, and observe regeneration.  So, be gentle with your worms.  Another note, ‘fetida’ means foul-smelling in Latin.  Yes, they smell if smushed.

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Worms need food – NO meat, dairy, citrus or onions.  Meat and dairy will attract maggots and flies, stinky and yuck (I might add stuff with dairy in it to my outdoors bins but not worms inside).  Citrus and onions just lower the pH of bin, worms like 7.0.  I put my citrus, onion, garlic stuff in outdoor bins.  Place the food under newspaper for worms to munch.  Everything eventually gets mixed around and the newspaper eventually decomposes too.  I add shredded paper at least monthly because of the size of all my worm farms.  And since I definintely have pounds of worms, I’m adding juice pulp, dinner scraps, rotten food in fridge, bread ends, coffee grinds just about every day (except when the chickens need it).   But I don’t do oranges in the juicer (squeeze by hand) because worms wouldn’t like it in the mixture.  Check out the Wormtopia Food Pyramid in photo below, they can eat most anything.


Their food can be leftover rice, pasta, bread ends that are moldly, juice pulp, avocado skins and seeds, melon rinds, and veggie scraps, of course.  I’m very careful of how many banana peels and other fruit because of fruit fly issues.  Just don’t overdo it, if you see tons of fruitflies in your good kitchen food, maybe you have a nesting problem in worm farm.  Just cover with more damp, shredded newspaper.  Always add the avocado pit (and any other pits or seeds) to the worm farm.  By accident, I discovered that they expand with moisture, sprout and grow…into trees, that I plant and give away.  They will never fruit indoors but make great gifts and houseplants.  Other things that sprout in bins: all the seeds from squash you threw in there, carrot top stubs, lettuce head stubs, potatoes that have eyes, onion stubs, beets, etc.


Remember, vermicomposting can have up to 1000 invertebrates associated with it.  Bacteria, fungi, worms, earwigs, spiders, and more are all part of this ecosystem.  A spider may web in your bin because you have a bunch of smaller flies, insects, etc that he can hunt.  That is great.  Ecosystems with many elements are more stable.  If fungus is growing like crazy, you’ve added too much food, they can’t eat it fast enough, thus mold takes over.  If your worms are crawling up the sides of your bin, material is too wet (anaerobic, they can’t breathe), or there’s not enough food (they’re looking for more).

Your worm farm should smell like a rain forest or at least the forest floor, like good fresh compost.  If you notice odors from your farm, you have probably added too much food material and it is rotting before the worms can eat it.  Remove the excess or just cover with more damp newspapers.  Excess moisture (anaerobic) conditions will cause the bin to smell, too.

Thanks for Supporting Global Worming!!

Time flies like the wind,
fruit flies like peaches – Unknown