Worm Compost Leachate, Good or Bad?

Image: Permaculturewiki.

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?

Getting started with worms

worms.81

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!

worm bin 3
Worm bins vs. compost piles

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.

Matching Your Waste Stream to Your Composting Method

Image source: Philip Cohen, Wikipedia.

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.

Maintaining a Worm Bin

worm bin 1

This image might represent a new low in aesthetics from the Root Simple Photo Department. And that’s saying something.

I freshened up our big worm bin today and I thought I’d report on what I did because I get a lot of questions about worm bin maintenance.

First, I want to say this is just how I go about it. Other people will have different methods and habits. Worms are forgiving and reasonably adaptable, so you have a whole lot of leeway in keeping a bin. As long as you don’t let the worms dehydrate, drown, bake, or utterly starve, you’re going to be okay.

Our worm bin is pretty big (5 feet long), and made of pine boards.  It bears an unfortunate resemblance to a coffin, but it works wonderfully. I used plastic storage totes for my worm bins before we built this, and while those worked fine, I really like my big bin for two main reasons. The first is the size. It can take whatever I throw at it. It takes all my kitchen scraps, except for the really choice stuff that goes to the chickens. The second selling point is that the wood breathes, and that seems to make the worms happy.

Maintaining the Bin

The Conceptual Divide

I divide my bin into two areas, left and right. There’s no physical barrier between the sides, just a conceptual distinction. Usually one side is working and the other side is resting. This division is easy to make in a long, skinny bin like mine, but can be managed in a smaller bin as well.

Basically, once you’ve got a worm bin going, there will come a time when you’ll need to harvest some of the castings. Those castings are valuable in the garden, and the worms don’t want to live in their own waste. You’ll know its getting close to harvest time when you see pockets of scraps here and there, but mostly the texture of the contents looks like soil or coffee grounds. Or maybe fudge, if it’s more wet and compact. Fudge is a less than ideal environment for worms.

In the picture at the top you’ll see my most recent working side. There’s a lot going on in there still, some big food pockets, wood shavings everywhere, but the texture is becoming too black and dense overall. Compost worms like a little air, a little “wiggle room” and a diversity of habitat. It was past time to change this working side to a resting side.

Resting comes before harvest. This is where dividing the bin in two comes into play. Resting means no more feeding, so that the worms will finish up whatever bits of food are left around. But of course you can’t starve out your worms, so you only rest half of the bin at a time.  To do this, you put your food scraps on one side only. The worms on the resting side will finish up whatever food pockets remain and then migrate over to the active side for the fresh grub.

This doesn’t happen quickly. I’ve never made note of how long migration takes–it will vary, depending on many factors. I just poke around in the resting side whenever I happen to think about it. If I don’t see anything recognizable beyond non-digestibles, like avocado pits, fruit stones and egg shell shards, and I know it’s ready for harvest.

There will also be a few worms left, no matter how long you wait. More on them later. If your bin is outdoors, other insects like sow bugs might be in there too, but are harmless.

This is the process in a nutshell:

When your bin is looking mostly done, ie full of castings, rest one side of it. This means you feed only on the opposite side. When all the recognizable scraps are gone from the resting side, you harvest the castings. Then you can put fresh bedding in the empty space, and start encouraging the worms to move to that side.  Soon, you will be able to rest the opposite side of the bin, and eventually harvest it. And so it goes, back and forth.

Continue reading…

The tale of the worm bin celery

parsley flower

This is related to my recent post about our flowering radish. It’s a tale of botanic dumpster diving and another reason why you should let your food plants go to flower when you can.

Last year I threw the crown (which is to say, the bottom) of a celery plant in my worm bin. I probably should have chopped it up for the worms’ sake, but I didn’t. Later, sometime in the fall,  I rediscovered the celery crown. Instead of rotting in the bin, it had sprouted leaves and looked surprisingly vigorous. So I pulled it out and popped it into an empty space in one of our raised beds.

I didn’t have much hope. Celery doesn’t like our climate much, and I consider it one of those plants which is easier to buy than to grow.

To my surprise, the plant did quite well, though it did have a feral quality to it, despite its mild domestic origins. It didn’t grow fat, moist stalks which can be used to scoop up peanut butter. It grew stringy, dark green stalks which tasted powerfully of celery. It made excellent stock, and chopped into fine pieces, it was good in soup, too. Since I don’t eat much raw celery, this suited me fine.

All winter long I used this plant as the basis of my cold-weather cooking–chopped onions, carrots and celery in the bottom of every pot. It was a real treat not to have to buy celery for such a long time, and to have that flavor available whenever I wanted it. I should add that the leaves were just as flavorful as the stalks

As a side note, I’ve heard of a breed of celery made to work precisely this way, called cutting celery, but I’ve never grown it intentionally. The celery in this post looks very much like my homegrown “cutting celery.” Perhaps commercial celery wants to revert to this?

Months later, the hot weather arrived, the celery started to bolt (that is, send up flower stalks). When a plant bolts, it puts all its energy into flowering. At that point, its not much use to us as food. I was sad to lose my bottomless celery supply, but I was excited about the flowers.

Pollinating insects love celery blossoms. Actually, they adore the whole family of plants to which celery belongs, called Apiaceae or Umbelliferae (which I tend to call Umbrella Fae, which is wrong, but right in my head). This family includes carrots, celery, dill, coriander, fennel, Queen Anne’s lace, etc. If you can let any of this family bloom in your garden, do.

The parsley flowers grew almost as tall as me, and they were surrounded by clouds of tiny insects every day –shy, tiny little pollinators that I can’t name.

I love to let things go to flower and seed in the garden, because it is a way of giving back to the rest of nature. Flowers for the insects, seeds for birds. And by giving back, you help balance your garden. We’ve had significantly less issues with destructive insects since we learned to let our garden go a little wild.

Sadly, this celery never got to seed, because it collapsed under its own weight one day. Its thick, hollow stalks folded and the head of the plant fell to the patio.  I had hoped to save a little seed and try to grow a plant the next year from scratch. But now I’m thinking I’m going to throw a whole crown of celery in the worm bin this fall, and hope this happens all over again.

collapsed parsley plant