How To Use A Worm Bin? (What You Need To Know)

Last updated on October 23rd, 2023 at 08:47 pm

Put the worms in a box, add organic waste, close the lid and the worm bin is ready. But it’s not that easy with the worm farm. What you should consider when you build a worm bin yourself, why buying a worm bin makes more sense for some people, and even more interesting facts about indoor compost, you will learn below.

What are worm bins?

A worm bin is an odorless indoor compost. A box inhabited by compost worms is the basis for a worm bin. In the worm farm, the worms decompose much of the organic waste produced in the kitchen and turn the waste into humus, or fertilizer. The more solid fertilizer is called worm humus, and liquid fertilizer is called worm tea.

There are two types of worm bins: one-box or multi-box systems. The one-box system consists of one box divided into two parts. Thus, by occasionally rearranging it, fresh organic waste can be stored in one zone and compost in the other. The multi-box system is built from two or even more boxes on top of each other and is more like a worm tower than a worm bin. There, the top box of the wooden box is filled with organic waste, which then slides into the box below as compost after being processed by the worms. In both cases, it then takes some time for the compost to become the finished worm humus (fertilizer).

How does composting in the worm bin work?

In the worm bin, nature’s nutrient cycle takes place in miniature: Microorganisms and compost worms decompose the organic waste into its individual components and prepare them in such a way that you can use the end products, worm humus and worm tea, as fertilizer for your plants or vegetable garden. From 80 to 200 liters of organic waste, worm composting yields 15 to 30 kilograms of “black gold,” as worm bin fans call the fertilizer produced by their crawling pets, every year.

The worm tea is collected in the lowest part of the worm bin and either drained with a small tap or skimmed off by hand. The worm humus lies in the part above and on top of it you place the organic waste that still needs to be decomposed. To keep your compost worms in a good mood, you should add paper (no glossy paper!) or cardboard from time to time and spray water into the worm bin with a spray bottle on hot days.

The advantages and disadvantages compared to a conventional compost.
Both backyard composting and worm bin composting turn organic waste into humus by worms and microorganisms. So what are the differences between the two systems? What are the advantages, but also the disadvantages of a worm bin compared to a conventional compost in the garden?

Advantages of a worm bin:

• You can put a worm bin in any niche or corner of the home. You don’t need a garden, a terrace or a balcony for a worm bin. A compost pile in the living room, on the other hand, is rather unusual.
• Worm humus and worm tea are always nearby. You don’t have to go out to the garden to fertilize your herbs in the kitchen on the side. Aside from the fact that worm tea is not even extra to skim off a compost pile.
• Worm humus is much richer in nutrients than regular compost: it has five to seven times the fertilizing effect.
• A functioning worm bin does not stink. Compost often smells.
• No unwanted roommates like rats or other vermin helping themselves to your backyard compost.

Disadvantages of a worm bin:

• Less organic waste fits in a worm bin than in a compost pile. A family that eats a lot of fruits and vegetables may need an additional compost pile to recycle all of their organic waste. Or several worm bins.
• As long as the worms always have something to eat and are comfortable in the worm bin, you won’t be able to get outside through the air holes. But theoretically it is possible.

Which container is suitable for a worm bin?

To build a worm bin yourself, you should have a plastic box or a wooden box. For worm composting it is important that the box has a lid, is dark and yet permeable to air, thus regulating the humidity inside. Also, the walls should not be too thin to better absorb temperature fluctuations of the outside temperature – important especially if the worm boxes are placed on the balcony. How you design the worm bin and whether you use it exclusively as a worm farm or, for example, as a (rollable) stool, a coffee table or a base for a kitchen herb bed is, of course, up to you.

Which worms move into the worm boxes?

Not all worms are the same – even though to the human eye there is almost no difference between earthworms and compost worms. For a worm bin you need compost worms, because these industrious little animals with sonorous Latin names such as Eisenia andrei, Eudrilus eugeniae, Lumbricus rubellus, Dendrobaena veneta and Eisenia foetida prefer to live in the foliage layer above ground and not underground, thus ensuring that the organic material is decomposed there. To do this, they eat a good half of their own body weight – every day. The more comfortable the compost worms feel on the worm farm, the more food they eat, the more they multiply and consequently the faster they decompose your organic waste. To make the compost worms as comfortable as possible, the temperature in the worm bin should be 20 to 25 degrees Celsius.

If you are using compost worms in your worm bin for the first time, you should settle three worm species in the bin. Dendrobaena veneta, Eisenia foetida and Eisenia andrei are particularly suitable. You can buy them in an angler’s store. With six liters of substrate in the worm bin, it is best to start with 500 animals. If your worm bin is smaller, you will have to reduce the number accordingly.

What can be composted in the worm bin?

In order for a worm bin not to stink (i.e. no putrefactive bacteria or mold to form) and for the worms to reproduce as desired, you should, in your own interest, only dispose of organic waste in your indoor compost that does not cause problems for the worms – and not too much of it, especially at the beginning. Otherwise, the worms will be overwhelmed and will not be able to decompose the compost before it starts to mold and stink. Normally, the worms process the organic waste into fine compost within 20 days. The worm compost then takes a while to turn into fertilizer: You can use the first DIY fertilizer six months after building the worm bin. However, worm tea is available earlier and should also be drained regularly, otherwise it too can become a source of stench.

These kitchen scraps may go into the worm bin:

• Eggshells
• coffee grounds
• loose tea
• fruit scraps and fruit peel (also banana)
• vegetable scraps and vegetable peelings
• Leaves and remains of plants (no wood)
• Paper and cardboard (if not colorfully printed)

These wastes are not allowed in the worm bin:

• Meat
• Sausage
• Egg white and yolk
• Onions (but peel is okay)
• Citrus fruits
• dairy products
• cooked, salted food
• wood
• cat litter
• oil

Build worm bin yourself: Helpful tips and tricks

• Before building the worm bin or worm tower, decide how you want to drain the worm tea. You can add a tap or plan for a cassette, which must be easy to pull out.
• Sufficient air supply is essential for frictionless and odorless composting of organic waste in the worm farm. So don’t skimp on drilling air holes, gladly further up the box.
• Use fine chicken wire to separate the organic waste zone from the worm humus or compost zone. This will also allow you to block the holes in the worm bin from the inside. Don’t worry, as long as the worms are comfortable in the worm bin, they won’t break out. But it will make you feel a little better, while still allowing air circulation, which is why you drilled the holes in the first place.
• Don’t skimp on the hinges for the lid. You will be opening the worm bin every day, so it should be easy to handle.

Cost of a worm bin

Things to consider when looking at the price of a DIY worm bin are:

Starting material: plastic or wood?
Size of the worm box
DIY performance: are you building everything yourself or are you building a worm bin into a purchased wooden box?
Not all parts for the worm bin can be bought in the small quantities you need. Hinges can usually only be found in packs of 24, and chicken wire by the meter. The quantity needed for the box is usually less than what is offered in the hardware store.

With a purchased worm box, you should check:

Is it a kit?
Are all parts for the worm box included in the kit?
Are substrate and worms included in the price?

In addition to the cost of a homemade worm bin, there are costs for the screws, drain cock or drawer device, as well as sandpaper and possibly handles for boxes to be stacked. From about 40 dollars material costs, you can build a three-storey wooden worm tower itself. A simple, stackable worm box made of plastic is possible from about 20 euros. You should also take into account the costs for substrate and worms. For 25 euros you get about 500 compost worms.