Worm Leachate

My class made this worm bin back in March, and I’ve been faithfully adding food scraps, as well as carbon-rich material, every week or so. Worm bins are actually made with TWO bins, one nested in the other. The ‘top’ one has a bunch of holes drilled in the base, to let the leachate drain out, which collects in the ‘bottom’ bin. Today, I checked to see if there was any leachate, and found about a cupful of liquid! At this point, you might be wondering: What the heck is leachate???

“Leachate” is a umbrella term for any liquid that, while passing through matter, extracts soluble material. Leachate from a worm bin can be a mix of things, such as excess moisture (too many food scraps, not enough carbon) or worm urine. In a regular compost bin, this sort of thing soaks in to the ground below, but when composting in a worm bin, which are often used in concreted places such as a patio or porch, it is caught be the bottom bin. This liquid can be used in the garden as a fertilizer, but it’s hard to know what exactly the liquid contains. So to be safe, the liquid should be diluted 1:1 and experts recommend that you only use it on non-leafy vegetables or fruit trees.

After diluting the leachate, I decided to apply it to the Milpa/hugelkulture bed that is a riot of different plants. The squash leaves in this particular bed have been looking a bit yellow to me, which indicates that they could use some nitrogen (not a surprise, since hugelkulture beds are made using un-composted material which require nitrogen to break down, leaving little for the plants). We’ll see if adding this diluted leachate helps at all. I’ll give it a week, and if I see no improvement, I might give it a dose of fish fertilizer.

I’ve been quite happy with this bed overall. It’s super fun to watch what comes up, what dominates, what flowers, and what’s producing fruit. There have been a lot of buckwheat flowers, and right now there are a bunch of sunflower buds. The peas grew, but never bloomed. The beans are doing quite well, and there is corn too, though it is very short. The squashes are the true stars of this bed. I’ve already harvested summer squash here, but I see a ton of winter squashes beginning to fruit, too. Hopefully the leachate will help those to grow big and ripen beautifully!

Reader Question - Vermicomposting

A reader named Jen writes, “I am considering getting a vermicomposter, and the options range from high end to low cost: https://www.epicgardening.com/best-worm-composter/ The Worm Factory starts at $146 and others are more moderately priced, in the $100 range. The Hungry Bin is a whopping $346! Here are my questions: Should I invest in a more expensive worm bin and if so, why? Should I release some worms into my garden so that the birds have more to eat over the winter? Am I really doing anything about the impending doom of climate change by vermicomposting?”

Full disclosure, Jen is a close friend of mine from childhood. She lives in NC, in Chapel Hill, which is USDA Zone 7b. She lives in a forested area and has a lovely Japanese style garden, as well as some meadow plantings.

We all know the benefits of composting, so I don’t need to go through those again. Our awareness of food waste has been growing lately, and it’s good to figure out some sort of system for dealing with that (besides re-thinking your shopping and cooking habits, which I’ve had to do myself with our teenage son away at college). Chickens or pigs is ideal for this - nothing gets wasted if you have livestock to eat your leftovers. But worms are another livestock option that are ideal for those of us who don’t have the property allowance for larger animals.

I’ve used worms in various ways for years.

I’ve had an official worm bin, which was used by and then given to me by a neighbor, and it was an interesting experience.

These are usually a set of stacked bins. The top few have a perforated bottom, to let worms and leachate move between them, and the bottom one has a solid bottom to keep everything inside. There is also usually a spigot of some kind which allows you to drain off the leachate (basically worm pee). You then dilute this liquid and use it as a fertilizer. Additionally, the castings (poop) are removed periodically and added to your pots or beds.

I found this sort of system high-maintenance. It needs to be in an area that is protected from rain (there are openings in the top to allow air circulation); the top is easily removed by predators who eat all the worms (hence my putting rocks on top); you need to have a lot of leaves or newspaper or some other carbon source available to soak up all the nitrogen that is being produced (poop); and, when it’s time to empty the bins of worm castings, you have to somehow “sift” out the worms, which is supposed to happen naturally with the perforated bottoms but, in my experience, doesn’t work. I used it for about a year and then put it in the recycle bin (after removing all the worms and stuff and putting them in my regular compost).

I can see that this sort of system would be perfect for someone who doesn’t have any outdoor space - a balcony, or a garage, or even a laundry room could host a stack like this. But the mess you make when you remove the compost would make it less than ideal for indoor spaces. If you have very harsh winters, this system could also be good, but again, not easy to maintain indoors. Some people make their own worm bins which is far cheaper than buying something pre-made.

Something I have found far more sustainable is to have an enclosed outdoor compost bin of smaller stature, one made of natural materials that is open to the ground below. My dad made me one like this years ago, a two-compartment bin of old redwood decking, with a hinged lid and removable front panels. Because the bin is so small (3’x3’x3’), it doesn’t hold enough material to get hot enough to break down easily. My way around this is to buy worms every other year, and add them to the bin.

There is likely a worm farmer near you, wherever you live, where you can buy a couple of pounds of red wigglers for about $20 a pound (which you’ll need to do for a worm bin, as well). They will mate and produce more worms, but they also crawl out of the bin and into the surrounding garden, get eaten by birds, etc. So that’s why I buy them every couple of years. They really speed up the composting of my smaller bin.

I don’t bother to add any worms to the big compost pile that resides in the chicken run. First of all, they’d just get eaten by the chickens. Secondly, that pile breaks down faster anyway for many reasons - it’s bigger (more volume), it has its own dedicated sprinkler, and it gets turned by the chickens every single day. There are definitely worms in it - I see them every time I go to collect the finished stuff at the bottom - which have arrived from the surrounding garden.

And that brings me to something else you need to consider - there are already a ton of worms in your existing landscape. They are there even if the soil has been neglected for years. They reside deep inside the moist layers of soil. Rain brings them closer to the surface, as does organic matter. If you have a woodsy area, worms are part of the great soil ecosystem that breaks down all that organic matter - only a small part, to be sure, as bacteria and fungi do most of the work of decomposing the litter that lies on our soil surfaces. The very best way to ensure that you have an active and healthy soil ecosystem is to provide it plenty of organic matter. Don’t remove leaves. Add mulch to bare ground. And you may even want to bury your food scraps out in the landscape - just dig a hole next to a bush or a tree, put your scraps in, and cover them with soil. This is called “composting in place” and many people swear by it. There is a permaculture method called a “keyhole” planting bed, which is a raised bed shaped like a circle, with one path in to the center of the circle so you can reach everything. In that center, you place a wire basket (open to the bottom and the top). In that, you layer leaves and grass and food scraps, and it breaks down right into your bed.

I even had a horticulture professor who basically laid his food scraps down around his fruit trees, not even bothering to bury them! This looks unattractive but is effective. In my neighborhood that would attract even more nighttime creatures, so I need a more organized way to deal with scraps.

As for the birds, something like 98% of bird species feed insects to their young, even if they are seed eaters normally. The young need protein, and the best source of that is insects. Birds need a variety and abundance of insects, and so if you appreciate birds, the best thing you can do for them is to provide insects. Worms that live in the ground are good for some bird species, but worms that live on leaves are much better for a vast number of bird species. Worms that live on leaves, also called caterpillars, are usually a larval stage of many insects. So, as we’ve discussed before, there are many things you can do to increase insects in the garden: stop using pesticides; plant a variety of flowering trees, perennials, annuals, vegetables, and herbs; provide water in shallow dishes; and allow for different habitats - some mulched spaces, some bare dirt spaces, tree snags, piles of logs, etc. Be a slightly messy gardener! Don’t clean up too much. For more on this subject. you would do well to read “Bringing Nature Home” by Doug Tallamy.

And as for climate change and the state of our planet, any action we take as individuals can only help the situation, so I encourage you to compost in any way you can. If a worm bin is going to be the thing that gets you there, then do it. Individual actions allow us to feel as though we are part of the solution and give us hope, so they are important from a mental health standpoint as well. But we also need to realize that it’s going to take global action and policy to really shift the world towards a completely different thinking about climate change. I’m not saying that your individual actions don’t matter. They do. But as individuals, we really don’t have the power necessary to make a significant change. That’s why we need to be proactive about voting for people and policies that support making these big changes.

I hope this helps you to make a decision about whether or not to get a worm bin, Jen! Thank you so much for your question. I’ll be interested to see if anyone else has some other advice for you, perhaps a system that worked particularly well for them, or ideas for making your own bin.

New Worm Bin

My next door neighbors are pretty awesome. Wes and Lavelle have lived in this neighborhood since it was built in the late 40's. They raised their children here, and are a big part of the community. They are often out walking their dog, or stopping by to bring me some banana bread, or helping me identify local trees. 

Lately the two have had some health problems, and it's tougher for them to get around. So one of their adult sons and his wife, recently retired, have come to live with them. This particular son is in the process of rebuilding the entire length of fence we share, which was built originally by Wes many, many years ago. The new fence is spectacular, and it's a lot of work. I'm enjoying having periodic open spaces in the fence to talk between houses, when Karl (the son) and I are both out working on our various projects. 

Every so often, Karl and his wife go back up to their property in gold country to take care of things there. When they came home from their last trip, they brought me their worm bin! Karl kept it so he would have worms ready for fishing, but since he's down here most of the time now, that hobby has gone by the wayside. He sees what I'm doing in our yard and knew I would appreciate another way of composting food scraps. So this worm bin is now mine!

He didn't just give me the bin, though. He also gave me all its inhabitants - thousands of worms - and the contents of the bottommost tray - the latest worm castings. Oh my goodness, this is like pure gold. Today I spent a good deal of time cleaning these out of the bin, separating the worms from the castings, filling the trays with bedding and old fruit/veg, and getting the bin all set up. The castings went into the containers that hold my Japanese maple trees - what a boon for those heavy feeders, a solid inch of nutrition as a mulch on top of the soil. The worms went back into the top-most bin along with coffee chaff as bedding, and some kitchen scraps.

There are four trays total. The top tray holds the worms and waste. As they eat, their excrement (castings) drop down through the tray to the trays below. And any liquid waste goes all the way to the bottom most tray, which has a solid bottom. That liquid is great fertilizer, but it can go anaerobic really quickly, so I just went ahead and filled that bottom bin with chaff to absorb the liquid. I'll periodically take it out and use it as mulch around my growing plants, and fill it up with fresh chaff.  If I used the liquid straight, I would dilute it first (way too 'hot' with nitrogen), but this way it is already semi-composted.

As I was going through the sorting/cleaning process, I noticed so many worm egg cocoons. So you know how worms often have that center band around their bodies, looking sort of like a cigar label around a cigar? That is where the eggs develop, and the worm wriggles out of it, allowing it to fold over on itself, and form these lemon-like egg cocoons. The babies hatch and look just like very tiny worms. Worms are both male and female, carrying both eggs and sperm, and they rub against each other to mate and fertilize the eggs in either worm.

By the way? Those big white things in this picture? Crushed eggshells that have never broken down in the worm bin, just as we discussed a week or so ago.

I'm happy to have another way to experiment with vermicomposting. As you know, I've used my 3x3 redwood compost bin as a sort of worm bin for years. This set up is a more streamlined affair. I'll continue to use both, plus my yard-waste compost pile, which is inside the chicken run. I'm finding that I really cannot have enough compost. I try hard to make all that I need, and I always fall short.