For three months we have a worm bin – our second, to be exact. Here’s our experience report!
A worm bin is what it sounds like – a box where compost worms live! The worms inside do nothing but chow down on clippings, poop out valuable fertilizer (“worm humus”) and poop all day long. What a lottery life!
We have a worm bin so we can compost in our spacious 30m2 one-room apartment in the middle of downtown Cologne. And all that without a balcony.
A life with worms at home
The question that I am asked by far the most often about the worm bin is whether it does not stink. I can reassure you, because no, it does not stink. When you open it up, the box smells like damp forest floor, so it’s a definite upgrade from the normal stinky kitchen garbage or organic garbage can. If it does smell unpleasant, that’s a sign that something is wrong!!!
As you can see in the picture, our worm bin even has a seat cushion on top. If it would stink, we would hardly roll it to the dining table as a substitute seating for visitors 😉. By the way, everyone who visits us always wants to see the worm box the first time! Every time they are positively surprised that the whole thing reminds more of a bed than a trash can.
And this is what it looks like in our box. In addition to clippings, cardboard and newspaper also go into the box. We also compost our sweepings (we don’t have a vacuum cleaner), hair, fingernails, tea and coffee grounds. Quite often, something also grows in our worm bin because, for example, bell pepper seeds germinate!
We are very pleased, the worms have visibly increased and I also see worm eggs here and there!
Actually, things like citrus fruits and onion peels are not allowed in because worms avoid such strong smelling things.
As with our old worm bin, we cautiously started feeding small amounts of onion skins anyway – as you can see in the photo above – when we felt the population was thriving and stable enough.
By the way, at the very bottom of the box has a catch basin for excess liquid. This liquid is called worm tea and is a very good fertilizer. Diluted with water in a ratio of 1:10, you can water your plants with it. Undiluted, worm tea can also be stored in a bottle, but the quality will decrease over time.
Harvest worm humus (fertilizer)
The worm bin is a so-called vertical worm bin, i.e. it has two “floors”. First, the crate is filled for about a month and then the green plastic crate is placed on top as the second floor. The plastic box has a grid at the bottom. The worms continue to feed at the bottom until they have turned everything into worm humus and, attracted by the food, move on to the upper floor through the holes in the plastic box.
After usually 4-5 months, the box is quite full and the worm humus in the lower floor can be “harvested”.
To harvest, you take out the top floor. But before you do that, you should lay out newspapers on the floor and push the worm bin onto it, because in any case something will go astray. If the weather is good, you can just do it in the garden, if you have one.
So our crate is already full and ready for harvesting after three months, and that, although we have even inserted feeding breaks in between, so as not to slay our worms with food. Overfeeding can cause a crate to “tip over” because the worms can’t keep up with the waste and it starts to rot. Because our crate used to be full, we also had worms in the bottom floor.
Now the worm humus can be harvested. I always remove the top layer, because the worms have crawled down. The worm humus goes into a bucket.
The worms I find when I harvest them just go into the top stick value, which is the green box. I also put most of the non-composted newspaper scraps in there.
The box is now empty except for some cardboard at the bottom, which has not yet decomposed.
I dump the contents of the former upper floor into the empty box. As you can see, there was already a good part composted, but still with a lot in between, which is not yet decomposed.
Then the green box comes back on top. The upper floor we fill directly again with fresh shredding waste and damp newspaper strips.
Apparently our crate was really unusually full! The green crate even peeked out at the top after the transfer! In that case, you can simply add some of the clippings to the top tray at the bottom, and the box will sit flush again.
What to do with the worm humus?
The worm humus can be mixed with soil (maximum ratio of 4:6 humus to soil). I have taken the harvest as an opportunity to repot a few plants. 😊🌿💕
Troubleshooting: fruit flies and fungus gnats
Unfortunately, we’ve been catching fruit flies and fungus gnats. The good news: fruit flies and fungus gnats are annoying, but generally not harmful.
Fruit flies come into the house with the fruit you buy because their eggs can be found on practically every fruit bowl. Unfortunately, I can’t tell you where the fungus gnats come from.
So we first put our worms on a diet and fed them very little, because that way there is also less food for the flying bugs. We also added ready-made worm humus on top from the lower floor and covered the whole thing again with damp newspaper strips and a damp newspaper, so that the worms but not the flies and fungus gnats get to the food.
With the box you also get a mineral mix, which you should sprinkle the worms once every 3-4 weeks. The mixture also binds the odors that attract fruit flies. We also sprinkled a good tablespoon of it on top. Then we left the box alone for a week.
The fungus gnats and fruit flies are basically gone now after two weeks 😊. If the fungus gnats do not want to disappear, neem oil helps.
The fruit flies that are still there do not come mainly from the box, but from our fruit basket, which I covered today with a tea towel. I think just now after harvesting the worm humus and the subsequent “reorganization of the worm box” they should no longer be able to multiply. According to experience, they go away anyway at some point on their own.
FAQ: Composting with a worm bin
Here I answer your most frequently asked questions about composting with a worm bin in the city apartment. What do I have to pay attention to? Does the worm bin stink? Where is the best place for the box?
If you have any other questions, feel free to read my other worm bin articles or ask me in the comments section!
What is a worm bin?
A worm bin is a box in which composting can be done odorlessly with the help of compost worms. Composting is the oldest recycling system in the world. You can bring this into your home with the help of a worm bin. The box itself is then a closed ecosystem.
Does a worm bin stink?
A worm bin only stinks if something has gone terribly wrong. Otherwise it just smells like damp forest soil. This is because oxygen gets to it. If your worm bin stinks, check if there is something too “tight” in it, so that no air can get to it. Then so-called anaerobic processes begin, i.e. it rots and stinks. And then the worms also keep away from it.
Definitely the more pleasant option compared to the normal kitchen garbage can or organic waste! Here I wrote an article about it.
Where is your worm bin?
In the kitchen. Not because it couldn’t go on the balcony, but because
The worms compost best at room temperature. We are too lazy to carry the clippings to the balcony every time. We are too lazy to protect the box on the balcony from direct sunlight and heat in summer, to tie it up in blankets in winter, to make sure that the box does not get wet during a thunderstorm...
How does such a worm bin work?
The worms eat, poop out compost and multiply. You can then use the compost directly for your plants and there was no need to haul trash back and forth. Here I have a detailed article for you about it 🐛.
Can I also build a worm bin myself? Or where can I buy one?
You can build it yourself or order one. Have a look here.
How many worms do you need? How many live in your box?
We started with about 500 compost worms. In the meantime, we certainly have several thousand. We have not counted them 😉. By the way, the fastest multiplier is the species Eisenia andrei.
Many worm box beginners also start with about 1000 worms, because a larger population makes the box more stable.
That means: Especially in the beginning it can be good to start with a larger population, which is more forgiving of mistakes. This is always my recommendation.
A typical mistake as a beginner is overfeeding. The worms are more likely to die from overfeeding than from underfeeding, because overfeeding causes the PH value in the box to tip.