reading time: 9 min
Well, then I have just the thing for you!
🪱 WORMS! 🪱
Cute little squirmy wormies. And yes, I do actually find them quite cute – in a squiggly-wiggly kinda way. 😅 (But I also think pill bugs are cute, so maybe I'm just very weird!)
You might have already read my accompanying blog post about this topic, where I shared our process of building a wooden worm bin for vermicomposting. Vermicomposting is the method of utilizing worms to break down organic waste and convert them into nutrient-rich compost, or vermicastings - which is just a fancy term for "worm poop". It's one of the best and low-maintenance natural fertilizers out there, and it basically comes for free!
All you need is
- worms that are suited for vermicomposting (see below)
- a well-ventilated container with bedding for them to live in, such as our wooden worm bin
- food scraps, garden trimmings, shredded newspaper or cardboard, and other organic matter to feed them with
THE RIGHT WORMS
Not all worms are suitable for vermicomposting. For example, the common earthworm or nightcrawler (Lumbricus terrestris) is not going to work here. Instead, look for Eisenia worms, especially Eisenia fetida and Eisenia hortensis (also known as Dendrobaena veneta or Dendrobaena hortensis) as well as Eisenia Andrei. In fact, it would be ideal to get a mix of all three for your worm bin.
The Eisenia worms are known for composting biowaste in the most efficient way, eating about half their own body weight every day. Insatiable little beasts!
For a worm bin our size, 500 worms should be sufficient for the start. For bigger worm bins, use 1000 compost worms, or more. If you've managed to create the right living conditions for them, they'll multiply quickly within a few weeks and fill up your worm bin all by themselves. After a while, the reproduction will reach a plateau due to the limited amount of food and space available.
As to where to get them: There are a lot of online shops where you can buy compost worms from commercial worm farms. However, we actually got our wigglers via a local community platform that works similar to FB marketplace. When I went to pick them up, the lady took them straight out of her own thriving worm bin. I brought my new "pets" home in two large ice cream buckets with air holes in the lids. And of course, me being me, I immediately gave our bunch of poopnoodles a name: They're called "The Ernies", named after Ernie from the show Maniac - a tiny little alien who was sent to help mankind (and is accidentally killed, but maybe let's not tell the worms that!).
Good to know:
- Add some Eisenia worms to your compost pile to give it a boost. Usually this is not necessary, since they naturally occur in healthy soil and should already inhabit your compost pile. This is why it's important to build your compost pile on top of soil, and not on top of stone slabs or plastic.
- Eisenia worms are also suitable for composting horse dung. In this case, get a mix of all three species, and use a large quantity such as 6000 worms.
THE RIGHT LOCATION
Keeping worms as "pets" (or farm animals...?) is really very simple and low-maintenance. All you need to, basically, is add some organic waste to their bin every now and then, and they'll be happy campers. However, to do their best, they need to feel their best. That means they need adequate food (we'll talk about that in the next section!), the right temperatures, sufficient oxygen and moisture. An environment that is slightly damp, but neither wet nor
dry, and temperatures between 10 to 25 °C (or 50 to 75 °F) are ideal.
Where I live, we have moderate to hot summers and winters with freezing temperatures. That means that I can keep my worm bin out on our roof terrace
in the shade for the warmer months (March - October), and once the
temperatures drop below 10 °C, I will move the bin inside to our barely
heated hallway for the winter (October - March).
If
you live in a more moderate climate than me, you might be able to
keep your worm bin outdoors year-round, such as in a shady spot sheltered from heavy rainfall on your
balcony or in your backyard.
If you live in a
region that experiences more extreme temperatures, or if you don't want
to relocate your worm bin twice a year (it's heavy!), you can also keep the bin
inside permanently, such as in your kitchen (very handy for feeding!), your utility room, an isolated cellar or garage.
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| What our initial bedding looked like ... |
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| ... 6 months later: ready for the first round of harvesting ... |
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| ... and 4 years later! Right before harvesting the right side of the bin. |
THE RIGHT FOOD
As I already explained in my last blogpost on building the worm bin, the worms' menu should consist of a healthy mix of "browns" (dry, woody materials that are rich in carbon) and "greens" (moist, often colourful organic materials that are rich in nitrogen).
Generally, about two handfuls of fresh food each week will suffice for our worm population. During the winter months the worms' activity will slow down, meaning they will eat and reproduce less, so we feed them less. In-between feedings, I use a loosely covered container to collect any kitchen waste that is suitable for the worms until it's time for the next feeding. This is not only handy for a weekly feeding routine, but it actually makes the scraps easier for the worms to digest as well. It also helps when you tear or cut the food into smaller pieces. (The cabbage leaves in the pictures above where way too big, but I didn't know any better back then!)
What to feed your worms:
GREENS / FOOD: adds moisture, speeds up decomposition, rich in nitrogen, energy source
- fruit & vegetable scraps: peelings, cores and trimmings, e. g. cucumber and carrot peelings, zucchini ends, wilted lettuce etc. (they love that stuff!)
- used coffee grounds and tea leaves
- wilted weeds and grass clippings (no seeds or roots!)
BROWNS / BEDDING: absorbs moisture, supports airflow, balances pH level
- shredded unbleached paper, e. g. newspaper, brown paper bags or unbleached paper towels
- shredded or torn brown cardboard, e. g. toilet paper rolls or egg cartons
- dry leaves or vines
- hay or dried grass clippings
- straw
- chopped twigs
- untreated sawdust
- sandy soil
- coconut coir
- aged manure
What NOT to feed your worms:
- animal products such as meat, dairy, eggs, fish etc. (yes, the worms are basically vegans, haha!)
- fresh manure
- pet waste or litter
- anything sprouting or containing germinable seeds (I learned that the hard way and ended up pulling out dozens of pumpkin seedlings that kept sprouting from unwittingly scraped pumpkin seeds!)
- citrus peels
- large quantities of banana skins, soft berries (their high sugar content can lead to fermentation and attract fruit flies)
- hot chillies
- spices
- processed foods
- moldy or rotten food
- glossy paper & receipts
- non-organic materials
The right balance between "greens" and "browns" is the key. You want the right carbon-to-nitrogen ratio as well as good airflow and the right amount of moisture. To keep the worm bin balanced, pair your nitrogen-rich greens with an equal or slightly larger amount of carbon-rich browns. So for each handful of food scraps you feed the worms, sprinkle a handful or so of cardboard strips on top. It's best to bury the food by a couple of inches of loose bedding, because the worms like it dark, and this will also reduce the likelihood of unpleasant odours and flies.
WEEKLY WORM CHECK
Like I said, keeping your worm bin healthy and thriving is pretty low-maintenance. But of course, as with any other pet, the worms need to undergo a regular health check. Once a week I will do a quick maintenance routine:
- Check for odours, pests and/or moldy food and remove if necessary
- Check moisture level and adjust if necessary
- Say hi to worms (they should be visible near the surface)
- Gently fluff up bedding to ensure good airflow
- Feed the worms (both greens and browns, or as needed)
This takes less than 3 minutes. We feed our worms once or twice a week, and adjust the amount of food depending on the season and the moisture level.
If your worm bin gets too soggy and starts to smell bad, go easy on the "green"
material, and add more "brown" material like shredded
paper, cardboard, or dry leaves to the bin.
If your worm bin gets too dry,
for
example on a hot summer's day, or because you forgot to feed your worms
for a couple of weeks (this has happened to me!), carefully moisten
everything with a little
bit of water, and add more fruit and vegetable scraps over
the next couple of feedings.
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| Hi there, Ernies! Everything alright in there? Okay, great, sorry for bothering you! |
HARVESTING THE WORM COMPOST
Now as fun as it is keeping worms as the ultimate zero waste pets that basically cost you nothing - there's another reason we're doing this, and that's harvesting the vermicast aka the worm poop!
As the worms do their alchemical magic of turning food waste into "black gold", the mix of "greens" and "browns" will gradually transform into rich, dark, crumbly compost that is packed with nutrients and beneficial microbes. After a few months, most of the bin will be filled with a dark brown, moist but crumbly substance that smells earthy and looks like coffee grounds or soil, with only few visible food scraps or bedding. This is your signal - it's time to harvest!
About 2-3 weeks before harvesting, you can push all the leftover food scraps to one side of the bin and switch to feeding the worms on just one side of the bin, naturally leading the worms to migrate there. Remember that handy divider we built into our worm bin? We used hardware cloth for the divider so the worms can easily relocate to any side of the bin. After a few weeks of feeding them that way, you can harvest the castings from the opposite side of the bin.
To harvest the vermicast, use your (gloved) hands and perhaps a spoon to gently scoop up the castings and check them for leftover worms, carefully sifting through the castings with your hands. A tray or tub makes the sorting easier. Any worms that I find in the castings, I place back into the worm bin (the side I'm not currently harvesting from), while the worm-free compost goes into a bucket or tub.
Leave a few inches of worm castings at the bottom of the bin to ensure a nice foundation of microbes on the emptied side of the bin. Refill with fresh bedding, like we did when initially setting up the bin. Again, if you have essential microorganisms (EM) at hand, use those to spray the cardboard bits.
Make sure to rotate sides when harvesting. To keep track, you could tie a piece of ribbon or fabric to the side of the divider that is up next.
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| Lovely, crumbly worm poop - the best natural slow-release fertilizer! |
USING THE WORM COMPOST
I store the harvested vermicast in buckets with air-tight lids until I'm ready to use it. Use as you would any other compost or slow-release fertilizer for garden and indoor plants. For example, sprinkle it into the potting soil when repotting houseplants; add it to planting holes when transplanting seedlings outside; mix it with coco coir for a nutrient-rich mulch; make your own seed starter mix by combining 1 part worm castings with 1 part loose garden soil and 1 part sand; add directly to your garden beds as fertilizer for heavy feeders like tomatoes, cucumbers and squash.
To use worm castings as liquid fertilizer, simply steep worm castings in water for 24 hours, using a muslin or mesh bag, to create what's called "worm tea". Pour finished worm tea around the base of the plant, or use as foliar spray.
And there you have it - a fully functioning and very easy-to-maintain worm bin aka your own natural fertilizer factory! Have fun with your wigglers!
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| DIY Wooden Worm Bin |
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