Image: PermaWiki.

In the course of preparing for our worm composting demo last week Kelly and I came across a lot of conflicting information. One of the most contentious issues in worm composting is what to do with the liquid that comes off the worm bin, called leachate.

The controversy stems, in large part, from the debate over aerated compost tea (ACT) vs. non-aerated compost tea. Fans of ACT do not like the fact that worm bin leachate is anaerobic, which they believe encourages the growth of microorganisms unfavorable to plants. They like to point out that worm bin leachate is not ACT.

The ACT debate needs a much longer post, but I did find two peer reviewed studies showing the benefits of un-aerated worm compost leachate: “Vermicomposting Leachate (Worm Tea) as Liquid Fertilizer for Maize“ and “Vermicompost Leachate Alleviates Deficiency of Phosphorus and Potassium in Tomato Seedlings.” I also found several Extension Service publications touting the use of worm bin leachate.

There are some caveats, however. First, it needs to be diluted–at least 1:1 and maybe, according to some sources, as much as 1:10. And you should probably test it out on a few plants before applying it to your whole garden.

And, from a food safety perspective, I’d avoid applying it to leafy greens and lettuces. I’d also point out that if you have a lot of leachate it might mean that your worm bin has too much moisture in it.

What do you think? Have you used worm bin leachate successfully? What side of the aerated vs. non-aerated debate are you on?

Tonight Erik and I are running a booth promoting vermicomposting at the Los Angeles Natural History Museum’s Summer Nights in the Garden. We’ve put together this page of resources and advice to point the newbie worm farmers we meet tonight in the right direction– and hopefully inspire anyone who’s reading, no matter where they live, to start a worm bin as well.

Welcome to Root Simple, NHM visitors!

Q: Why should I keep a worm bin?

A: To turn waste into a resource

Every kitchen produces food scraps, and most food scraps end up entombed in a landfill. It’s estimated that 20% of landfill material is food waste. This is unfortunate, because food waste is full of nutrients which will make your house plants, your landscape plants and your vegetable garden grow strong and healthy.

Worm castings and vermicompost, the products of a worm bin, are superb soil conditioners and plant tonics. Some quick definitions: Worm castings , also called vermicast, are worm poo. Vermicompost is the product of a worm bin, and it’s made mostly of worm castings, along with some compost material–that is, broken down organic matter. Vermicompost should have no recognizable ingredients–like newspaper or food scraps. It should all be dark and it should smell like soil. It is not exactly fertilizer, but acts in some of the same ways. Vermicompost adds nutrients and good bacteria to the soil and help soil retain water. Plants love it.

In a worm bin, your garbage becomes black gold!

While vegetable scraps can also be put into compost bins, not everyone has the space or the time or the physical strength to maintain a compost pile. Worm bins, though, are easy to maintain and can fit into every lifestyle, from a single person living in an apartment to a big family on a rural compound.

It needn’t be an either/or choice. Many people have both compost piles and worm bins. We find it useful to have a worm bin for the every day flow of kitchen scraps, while we use a compost pile to deal with the plant material generated by the seasonal clearing of the garden.

Where do you get worms?:

The best way is to get a scoop  from a worm keeping friend. I believe that worms, like sourdough starters and other cultures, really work well as a community project, because sometimes things just go wrong, and it’s nice to know you can knock on somone’s door and get some more.

However, you can buy them. Good nurseries sell them–make sure they’ve not been sitting around too long. Bait shops sells them. Check for them at your local farmers’ market. There are mail order companies too–do your due dilligance and make sure the company is well reviewed, and in its copy and fine print seems to put the wellfare of the worms as a high priority.

The most common kind of composting worms are Eisenia fetida, called red worms, red wigglers and composting worms. If you go to a bait shop, make sure you don’t buy nightcrawlers, because they won’t survive in a worm bin.

Choosing a worm bin:

In choosing a worm bin, you need to think your lifestyle: How much food waste do you produce? Where will you keep your bin? It is entirely possible to keep your bin indoors–when maintained correctly, they do not smell or leak. Many people find a place for a small bin in the kitchen, perhaps under the sink. They also can go in places like laundry rooms and basements and garages. Some worm bins are purely functional, others quite attractive.

Let’s break down some of these factors:

Indoor or outdoors?

Worm bins can also stay outside, with a few caveats. Worms like temperatures similar to the temperatures we humans enjoy. They don’t like being hot or freezing cold. They’re most comfortable and productive at the same temperatures you like to live in: around-abouts 55°-80° F (12°-26° C).

This means that while they can go outdoors, on a patio or balcony, they should be sheltered from extreme conditions. Keep the bin out of direct sun. When summer temps get into the 90’s (32+C) and above you need to help keep them cool. Keep them in the shade, up and off hot surfaces like blacktop. Be sure to add water to the bin as the heat begins to dry it out. Move your worms indoors if necessary. Expect that your worms will not be productive, and may experience some die off, during the heat of summer.

When winter temperatures drop low, you will also want to protect your worms. Again, bringing them in for the winter is the easiest solution, or to a semi-sheltered place, like a garage or basement. At temperatures around 40°F (4.4°C) they’ll survive, but won’t do much eating or mating. Lower than that, and you’ll start to see your worms dying (though we’ve heard from Chicagoans that their eggs will  live through the winter–and hatch when conditions are right again).  If you want your bin outdoors year-round in a cold climate, you will need to insulate the bin.

Also, remember to keep the bin out of the rain! You don’t want all your worms drowning in a surprise shower.

Finally, you want to make sure that your outdoor bin has a secure lid, so that it is not invaded by critters who would like to eat your worms.

While protecting worms from the elements requires some care, there are advantages to an outdoor bin. The foremost is that you have less to worry about in terms of insect infestation. It is common, and healthy, for worm bins to host all sorts of insects other than worms. They help with the business of breaking down the food. However, if this system falls out of balance, and you have an explosion of sow bugs or fruit flies in the bin, it’s nice to have the bin outside. On the other hand, outdoor bins naturally tend to hold and attract other insects, so outdoor bins by nature are a little more busy, insect-wise, than indoor bins. We think of this as a positive trait, but if you don’t like seeing the other bugs, you’ll have an easier time with an indoor bin.

And it’s worth repeating that a well-maintained worm bin is odorless, whether it is kept indoors or outdoors.

Bin size:

In the classic book, Worms Eat My Garbage, Mary Applehoff has a basic formula for worm bin sizing– you need 1 square foot of surface space for each pound of scraps you anticipate producing per week (1/10 square meter per half kg.)

However, keeping worms is not rocket science, nor is it an exact science!–and whatever bin you choose can be made to work.

Bin Types

There are all sorts of commercial worm bins for sale, ready to use, like the Worm Factory and similar stacking systems.  You can also make your bin yourself. Worms are not picky! Humans can worry themselves a lot over bin details and design, but as long as the worms have the right living conditions (even moisture, some air, not too hot or cold)  they don’t care if they’re kept in an old bucket, or an Ikea bag, or a rusty bathtub.

The two basic forms of DIY bins are the plastic bin built out of a lidded storage tote or a wooden bin shaped like a chest. This worm composting pdf from the University of Kentucky Extension has a plan for a simple wooden bin.  Here at Root Simple we have a big wooden bin which we keep outdoors, after years of working with a small plastic bin indoors, and find we like this bin very much, partly because of its large size, and partly because we believe wood is a better environment for the worms, and partly because we like the convenience of having a bin outside. But this is not a good option for all people. Small plastic bins are simple to make and work well just about anywhere.

While building a wooden bin take some basic carpentry skills and tools, it’s easy to make a plastic bin. To make a bin out of a plastic tote. All you need are two sturdy, opaque plastic bins (like Rubbermaid bins) and a drill. Here are two resources for how-to build a plastic bin. One is at vermicomposting.net. Another is in pdf form, available through this link to Oregon State Extension Services.

Our favorite resources:

It would take pages and pages for us to tell you how to make and maintain a worm bin, or explain the general amazingness of worms, and this information is already freely available on the Internet. So for further instruction, we’d point you to the following sources:

Oregon State Extension Services,  Composting with Worms. Mentioned above, it not only tells you how to make a plastic bin, but it is also a concise guide to all aspects of worm keeping. A great starter resource.

For general worm biology, The Adventures of Herman, published by the University of Illinois Extension, is a great resource for both kids and adult who just want the basics.

If you want a book on the subject, Worms Eat My Garbage, by Mary Appelhoff. remains the classic resource on aspects of vermicomposting (that is, keeping a worm bin) It’s been in print for a long time, so is easy to find new or used or at the library. Appelhof’s book has everything in it, from plans for building wooden bins, to feeding and harvesting, to explanations of the worm’s life cycle, to detailed trouble shooting.

Image source: Philip Cohen, Wikipedia.

This past weekend I taught a composting class at a local Waldorf school to a group of adults. When I asked the students to describe their living situations, I realized I needed to take a detour from the main activity of the day, building a large biodynamic compost pile, into a discussion of worm composting.

Why? A few of the attendees lived in apartments or had very small yards. The type of composting your household does will be determined in part from how you manage your waste stream and what you intend to do with the compost. If you live in an apartment and just have a few house plants, a worm bin is going to be your best option.

Even if you have a yard and a vegetable garden you may still need to maintain a few different types of compost methods. We have three kinds of composting methods at our house, determined by the types of waste streams our household generates:

Worm bin
Our worm bin is for the trickle of food waste that comes out of the kitchen on a daily basis. This consists of vegetable trimmings, tea bags and coffee grounds.

Advantages: Can be done indoors in an apartment. Produces a compost that is higher in nutrients than a conventional compost pile.

Disadvantages: Certain foods can’t be added like citrus and onions.

Conventional compost pile
If you have a vegetable garden and want to grow organically, you’ll need to generate a large amount of compost. This is a great way to deal with yard trimmings, grass, manure, and food waste.

Advantages: makes the kind of high quality compost needed in large quantities for a vegetable garden.

Disadvantages: a lot of work, can’t be added too once the pile is built, may require car trips to gather materials.

“Disposal” compost pile
There’s also stuff that can’t go in the worm bin. And once you build a big pile it’s best not to keep adding to it. For this reason we have a kind of “disposal” pile. It’s a compost bin that gets the materials that can’t go into the other two.

Advantages: reduces the biomass of all the stuff that can’t go either in the worm bin or the big compost pile.

Disadvantages: produces a low quality compost.

Alternatives
The labor involved in building a big compost pile for a conventional vegetable garden speaks to the advantages of what I think of as alternative permaculture food crops. In our climate that’s things like prickly pear cactus, pomegranates, certain types of grapes, olives and California natives (many of which are edible or medicinal).  These useful plants don’t need compost. They pull up nutrients from the ground and, if you let the leaves fall in place, do their own composting.