I’ve been looking forward to writing this post for quite some time now. As I mentioned in the post about my restaurant vermicomposting project, the trench idea started as somewhat desperate attempt to deal with the large quantities of food waste I’ve been receiving each week. Since that time, it has become much more than that – I like to think of it as a long-term, slow-release, natural fertilizer factory (or LTSRNFF for short – haha).
I situated my first trench directly in front of my tomato bed, thinking that it might help them grow somewhat better. Unlike last year, I decided not to add slow-release fertilizer sticks so that I could see the full potential of the natural method (or all of the negative repercussions if it didn’t work). One thing I was somewhat concerned about was the fact that I didn’t set up the trench well before the planting of the tomatoes – in fact, the trench ended up going in a week after the tomatoes were planted!
My concern revolved around the fact that I was adding lots of stinky, anaerobic waste (from other food waste composting attempts gone wrong) and materials that were not very well stabilized (decomposed) in general. It is known that various phytotoxic compounds can be produced via anaerobic processes, so I worried that I would end up stunting the growth. The ideal situation would involve setting up your trench months before you plant anything, so that by the time they go in, there is a rich supply of composted materials to start tapping for nutrients.
As I have discovered however, a trench can really go in at any time! I’ve seen no indication that the plants have been suffering as a result of their close proximity to the trench – and I think that right there is the key – the “close proxity”. You are not, after all, planting your crop directly in anaerobic sludge. You are basically giving them the option of spreading their roots in that direction. The interesting thing is that they do in fact seem to send roots into the material (composted or not) quite quickly.
One thing that likely helped my tomatoes right off the bat was the fact that I added a scoop of Worm Power worm castings into each hole. As I’ve discovered this year, worm castings are a fantastic material for helping any plant get started, whether it be a seedling or a transplant.
Time to move on to the actual creation of a vermicomposting trench. The set of photos I’ve included below actually feature the third trench I installed this year – basically a continuation of the tomato bed trench. I recently wrote about my lack of gardening skills over at CompostGuy.com, and this was a prime example. I planted this bed (which contains zucchinis and several different legumes) way later than I should have, and again dug the trench even later still. Yet again, the composting worms have come to my rescue – I added quite a bit of worm compost (harvested from my outdoor worm bin) into each hole, and more was added as a top dressing as well.
The first thing I (obviously) had to do was dig the actual trench – certainly the most labour-intensive and tedious part of the job. The depth and width of the trench is definitely up to you. I chose not to go down quite as far with this trench as I did with the one in front of the tomato bed. Keep in mind, the deeper you make it the more anaerobic it will be down below. This may or may not be an issue – just something to consider. Deeper (and wider) trenches have the advantage of being able to hold more material.
Next, I added a lot of coarsely shredded corrugated cardboard. This creates a bit of a ‘false bottom’, helping to absorb excess moisture from the rotting waste materials, as helping to balance the C:N ratio of the mix (I like to err on the side of higher C when vermicomposting).
It may look like straw, but this is actually partially decomposed material from my backyard composters. As you may recall, I had zero luck when I initially tried using my backyard composter (only one was active at the time) to compost food waste, but once I had a lot of straw available I was able to start using the composters again – with much greater success, I might add.
This pre-composted material should create a good ‘habitat’ for the composting worms added later. You don’t really need to add this (I didn’t add any to my first trench) – I just happened to have it on-hand, and knew it would work well in the trench. This is important to keep in mind when building a composting trench – don’t focus so much on exact instructions as you do on the principles involved, and the materials you happen to have on-hand. If I installed 5 trenches, I can pretty well guarantee that they would all be different – BUT, they would all be constructed with the principles of vermicomposting in mind.
Here is another layer of shredded cardboard. This time it was shredded egg flats (from the restaurant) – in my opinion, the best kind of cardboard to use for vermicomposting. As you can probably tell, the vermicomposting trench is set up in a ‘lasagna composting’ manner, with alternating layers of ‘greens’ and ‘browns’ (again, with more emphasis on browns, since it is a worm system).
Next, I added a lot of chopped up food waste – apple peels and cores, carrot peels, turnip peels, lettuce, broccoli stalks, egg shells etc. It was added in fairly shallow layers, but given the length of the trench, it was actually quite a lot of material.
I’ve actually left out a couple more alternating layers (I’ll include everything in the video I’m going to make), but I think you get the general idea. One of the important steps not shown was the addition of composting worms. I basically just harvested a LOT of partially mature vermicompost (containing lots and lots of worms) from my outdoor worm bin and added it as a layer over some moistened coconut coir. I have continued to add more worms since then as well. If you want to get your system working for you very quickly, the best bet is to add a lot of worms at once – you may however want to get yourself a compost thermometer before doing so. Since these trenches can hold a lot of material, they can also heat up quite a bit – the last thing you want to kill your worms or cause them to leave the area.
The final step involved adding a nice thick layer of straw. This helps to keep moisture and bad odour in, and hot sunlight and worm predators (like Robins) out.
That’s pretty much it! So far, I’ve been blown away by how well these trenches are working for me. My tomato plants are literally bigger than any tomatoes I’ve ever grown before – and we’re only part way through the season! I think the limitless water-supply (released from rotting waste) and readily available nutrients, combined with the seemingly-magical growth stimulating properties of worm castings has created the ultimate environment for ‘growing stuff’. I’m not 100% sure I would see the same results with trees, shrubs and perrenials – but I’ll certainly be interested to find out!
Needless to say, I’ll be providing more updates as the growing season progresses. As mentioned, I will also be putting together a video all about making a vermicomposting trench.
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jason: i don’t think worms will survive in fresh horse manure. i believe the worms eat stuff that bacteria (or fungi>??) have already inhabited and partially broken down. “rotten” would be a good word to describe worm food… though it does not have to stink or smell like anything at all.
The worms also need a bedding, which is also a lot better if it’s rotten. bentley’s right — you are best off making a bedding for them using materials that have been sitting around for a long time, getting moisture and darkness. think of a bale of straw left outside over the winter. you need a Carbon-heavy medium (straw, paper, leaves or, yes, manure) for the worms’ bed. manure generally comes with bedding (C). Piled up, it’ll settle down into a perfect bedding.
in that bedding, you will be able to place food. the food will sit in that dark, moist environment and begin to rot. soon, it will be good worm food. the worms will flock to it and turn it into worm castings (plant food) and more worms.
I’ve tried putting worms on a fresh horse manure pile. Actually, I think the pile may have even been a couple months old. Anyway, I found dead worms where I had left the live ones… Now, however, due to our mild & wet winters here, the redworms have somehow been able to spread all over the property. They pop up anywhere that’s a suitable environment to them — under boards, under a pile of weeds, in my (older) compost piles… I don’t know how they do it; they must be very happy.
Matt: worms eat rotten stuff. it has to already be dead. they will never kill any plants, only help them.
bentley: hey, i built my first couple worm trenches this winter… they are successful, and i give you all the credit, because i got the awesome idea completely from you. anyway, the trenches are along beds that are also hugelkultur creations — buried wood under the bed to store/provide moisture and oxygen. I constructed the 2 beds as part of a class presentation, so i’ve got photos of each stage of them. i’ll send you the pics if you’re interested for any reason.
keep trenching! your technique is very valuable to me. it should be more well-known!
Matt – sorry for the delayed response! Glad to see that Yoder responded, and provided a great answer. Bottom-line, there is definitely no worry about the worms harming your plants. The only time I could imagine that happened is if the worms are being grown in the exact same system as the plants (and it certainly wouldn’t always be the case – primarily only if there are small, delicate seedlings – the movement of the worms my disrupt their growth somewhat). Given the separation in the case of the trench, this would never be a concern.
Yoder – Great to hear that you are doing well with your trenches! I will certainly be writing a lot more about mine again this year once i get a bit more active in the garden. Will actually be putting together a video about my trench systems soon as well.
I’d love to see your photos, and if you ever wanted to share what you are doing in the form of a guest blog post, please let me know. I think a lot of people would be interested!
hey… what’s a “guest blog post”. i might be interested.
i’m learning a whole lot about soil happenings in school right now, and the funny thing is that worm castings still seem to trump everything in terms of reliability, efficiency and effectiveness. i try not to get too excited; i’ve still got a lot to learn. gotta keep the nose in the books, try not to think about the delightful smells emanating from the garden’s various nooks. haha — one of my compost piles cooked, cooled off, got rained on (some), and now is a gigantic worm nursery. i need some bait to lure the poor worms away from the stack before i distribute its contents amongst the trees and veg-beds.
busy busy. photos soon, i hope.
YES — get that video out there man! these trenches are the solution!!
oh yea, and the day that i wrote all that stuff responding to matt and jason, just afterwards i found your link to the youtube vid on the basics of vermicomposting. i thought, “wow, i just totally wasted everyone’s time typing all that up.” it’s all there, more thorough, simpler and more organized than I could have ever put it. congratulations on that. it inspires me.
Hi Yoder – sorry for delay.
A guess blog post is simply you writing about your trench and me posting the article on the blog. If you have your own website already I’d certainly be more than happy to link over to it from the article as well.
Totally up to you – just tossed it out there in case you might be interested.
Thanks for the kudos – I just keep on keepin on and hope that people find value in my work.
I think keepin on is the thing to do. this is one of my favorite web sites; whenever i find a person to talk to about worms, i always tell them to check this place out.
say, i don’t know if you mentioned it, but a word search on this page couldn’t find anything— It would save water in this climate to have the trench on the North side of a shade-providing plant or row. Just something to consider… it would also get colder in the shade during the winter, but if you plant annuals to its south, ….. (perennials to its north?? i wonder about woody perennials liking fungally-dominated soils…)
anyway, thank you very much for the opportunity to share my experience. I apologize for taking up so much room on your trench comments. haha… I’m pretty busy right now, and I don’t know how often I’ll have news on my trenches.. Maybe i’ll take you up on the offer soon, but not just yet.
i do have one really exciting thing that I want to share… I planted a 6-pak of artichokes in various places around the property, all with plenty of sun. The one that I put IN the worm trench is way bigger than the rest. Hi-five, worms.
In a class lecture the other day, teacher was talking about commercially-sold soil humates, how they are expensive, non-sustainable, etc. .. then I was pleased when he said that worm castings are the most highly valued form of humates.
ok very long. sorryl.
I am a wormer and an avid tomato grower. I didn’t see an update of the tomato harvest for the bed with the trench. This seems like a great idea, though in southwest Missouri, there are so many rocks that I might have to use a little dynamite to get a trench as deep as yours.
There seems to be a pretty good population of Milwaukee vermicomposters, doesn’t there? For anyone else in this area interested in getting worms, go to Growing Power. They charge $25 for a 5 gallon bucket full of worms and bedding (and don’t worry, you’ll be getting LOTS of worms in there). There are only 2 catches to this. (1) you MUST bring your own bucket. They won’t sell you one–believe me, I tried! (2) They will quiz you on your worm knowledge. The questions aren’t terribly challenging, but they do want to make sure that you stand a good chance of keeping the worms alive.
Bentley–I suspect you have already heard of Growing Power, but if you haven’t, they’re a pretty neat organization. Their founder is working on sustainable agriculture and making fresh produce more available to inner-city kids/families. Vermicompost is central to his mission and he composts not only food waste but also brewery waste from some of Milwaukee’s smaller brewery’s. He’s also involved in aquaponics, as I know you are. http://www.growingpower.org/Index.htm
MIKE – Not sure what you mean in terms of tomato harvest “update”. I talked about it a bit in the video and showed pics, but did not provide total weights or anything (is this what you were hoping for?).
I hear ya on the rock front – definitely NO fun when you run into them full-blast with your shovel!
ANNA – Growing Power is an awesome organization. Sounds like I have a similar approach with my own (Canadian) worm business – I switched over to a “worm culture” approach (essentially providing customers with worm-rich material) and am always keen to know what sort of system they’ve set up (“you DID set it up ahead of time, right???!” lol) to make sure the worms are going to a good home.
Sorry, Mike – you got me all mixed up here! I thought this was my recent vermicomposting trench video post we were commenting on!!
I recommend you check out the Vermicomposting Trench section on the Hot Topics page to see all the posts, updates etc:
I live in the South, hot summers & cold 10-20F(-15/-5C) winters.
My only problem with an outdoor worm bed is Fire ants, we have 4 kinds here, we also have killer honeybees, but that another blog.
Most people put the worms in old bathtubs or large containers on a wooden frame of 2X4 with the legs in bowls of oil. this stops the ants from killing & eating your worms.
Anyone from the South have a plan to stop the ants from getting in the trench system. Cinnamon & Bone meal works on deer & many bugs, not Fire ants or dogs.
Hi guys, first time poster here and I am intrigued by this fantastic idea! Let’s if I got the assumptions right.
1. The trench is an inground lasagna bed with addition of purchased worms.
2. The trench with wet green stuff will not only feed the worms but also as a source of moisture for the targeted plants.
3. The trench needs to be relatively close to the planting area so the worms can move around the targeted planting area and for the plants’ root to reach the moisture.
4. The soil improvement of the planting area is done mostly by the worms and not the composting?
5. Since the trenches are relatively deep at 18-24″, it’s more efficient in helping the deeper roots since norm rototillers only tilt 6-8″?
Is my assumptions are right, then
1. How close must the trench to the planting area?
2. How often would the trench needs to be refilled?
3. How many worms per say 120 ft3 of trenches?
4. If lack of large amount of kitchen waste, can I use Alfalfa hay as green, straw as brown? What about shredder leafy branches of freshly cut hedges?
Thanks for helping.
I live in SC, zone 7 our summers are high 90’s winters can get into the 20’s. Is a 2 foot trench deep enough to protect the worms from our heat? My purpose in vermiculture is to develop decent soil. My soil is clay. Will trenches fulfill this need? We can dig as many trenches as are needed. Your articles have been of great value.
Hi everyone – sorry for the lack of responses on this one!
JOEL – you’ve raised an interesting issue. I have a friend in Texas who uses vermi-trenches, but I can’t recall what (if anything) she has done to deal with fire ants – will need to touch base with her about that.
TOFFEE – Your assumptions sound pretty good, although I would say it’s the vermicomposting process in general (not just worms) that provides the overall benefits. Also, while this can certainly benefit deeper roots, it can also really benefit the upper roots (this is where I’ve seen LOTS of evidence of roots growing right into the trench in fact)
How close you make the trench is up to you – it would probably just depend on the plants you are growing. I probably put my plants 1-2 ft away from the trench most of the time, although last year I actually planted some tomatoes right in the trench.
I recommend feeding the trench on a regular basis. With food wastes during the summer, you would likely need to provide a good feed at least once ever week or two in order to limit sinking and provide the worms with a good supply of food. With materials like manure you can probably get away with longer periods between feeding since the volume doesn’t get reduced nearly as much.
I don’t recommend adding a lot of worms initially – maybe start with a pound at the most. The last thing you want is to spend a lot of money only to discover that they don’t like the habitat. The best way to introduce them is by dumping in worm-rich material from another vermicomposting system – this way they have a protective safe zone to stay in if the trench is not providing the right sort of environment.
Rotten alfalfa is fantastic stuff AS LONG AS you can keep it nice and moist – you may want to mix in some absorbent material (shredded cardboard etc) as well. Just using straw and hay may result in a mix that dries too easily, which will lead the worms to venture off.
PAT – Our summers generally don’t get that hot, so I can’t say for sure – but my suspicion is that you would be totally fine, as long as you have ample protective bedding over top. I have heavy clay soil myself, and have been amazed with the impact that my trenches (and other vermigardening methods) have had on my yard.
Seems like not much is known about the benefits of wood being used in a garden….and your right, the big wood pieces used in pathways and ground cover don’t break down fast enough to be of use in a compost pit……My method was to go to a logging/lumber site where they produced lots of sawdust each day and use that….mostly because of the Nitrogen content in it I used it in my garden where I planted potatoes….dig a trench about 10 inches deep, place a 4 or 5 inch layer of sawdust down, cover with grass clippings that have been heated until very hot (in plastic bags sitting in the sun) andopened to cool, a layer of dirt to finish filling the trenchand then put potatoe eyed skins spaced apart in hills over the top….easy to build, very little intrusive plant grown around your potatoes, and so easy to pull from the ground once the plants have matured……Good work on you web site Bentley..so glad to see your postings
john, wood (and therefore sawdust) has an extremely HIGH C:N ratio, which is to say the opposite of what you said: it has virtually no nitrogen, and will continue to “bind” up any would-be-available nitrogen in the area as it breaks down (this concept is discussed a lot in composting literature and conversations).
Here’s my best bet as to why your potato technique works so well: Wood is almost pure carbon, but it’s “tough” carbon, so it breaks down relatively slowly (therefore eats up nitrogen slowly), compared to other forms of C (e.g. straw, paper, etc, which are “softer”… read “Teaming with Microbes”, which goes further, into bacterially- and fungally- dominated soils). Sawdust has many times the surface area as wood chips, which will work the other direction — faster decomposition, faster nitrogen-eating. But it will still go slowly. I bet your sawdust is acting primarily as a sponge that retains moisture, and an aerated medium to provide your roots with oxygen. It will also add Organic Matter to your soil as it decays, which will still hold moisture, but also nutrients, and it will provide habitat for microbes, which are the ones doing all the work (they’re the ones the worms are after)!
The grass clippings would have a fair amount of extra nitrogen to feed your ‘taters, so it’s likely a great plan to have them between the plants and the shavings.
i wish i knew where to get a bunch of free wood chips! luckyyyyy…
bentley, i’ve got a new Worm Windrow that i’m building little-by-little using kitchen scraps, chicken poop and straw. The worms love it, and the chickens love me for it. When i peel back the tarp, they crowd around and gobble down any worm in sight. Not kidding, the worms themselves are what brought us together as friends.
Now that chicken poop is almost converted to worm poop to the point where i can turn it into plants! woowoowoo
Great response, Yoder! (hope that helps, John – thanks for your words).
The new system sounds great – drop me an email sometime to let me know what all you are doing these days.
Why is it not attracting rodents?
Hi, i realise that i’m late to the party on this one but i’ve just woken up to the fact that my entire garden has been a waste of space. i’m doing loads of reading about permaculture and all things green and sustainable which is how i found you.
my question is do you see this working on a smaller scale in a shaded garden bed? I have a garden bed on a patio under a roof which alternates semi opaque with completely opaque panels.
At the moment nothing is growing there it’s just a patch of sand but it’s right outside my back door. I’m thinking that it might be the perfect place to put an inground worm farm because it’s in almost complete shade? I live in Perth in Western Australia which gets really really hot in summer which is the other reason that i thought this may work better in the shade? Any advice really appreciated 🙂
As I undersand it you garden in the spring & autumn, because it is too wet in “winter” & too dry/hot in summer down under.But you should be able to build the soil with compost & worms, to make a great garden.
I double dig my raised beds, use compost, leaves, grass clippings & coffee waste, chaff & grounds in my trench garden.
I use burlap bags as mulch also.
Run over leaves & larger materials with a lawnmower to shred them.
Blood meal,bone meal, soybean mill, rock dust are all good too, but they cost money. I get leaves, grass clipping & straw free, every autumn in South Carolina, USA.This is a great site glad you found it.
Thanks for the advice and encouragement, it sounds completely possible 🙂
I’ve read as many comments as I can so hope I’m not repeating, but do you store your browns and greens separately before adding them to your trench?
I have a lovely yard but I rent so I hope to have a very clean raised and somewhat mobile container garden setup (horse troughs, cement mixing tubs on wooden stands) next year and am looking into the best way to apply this method, and start storing compost immediately.
So what will you do next season? Dig out the trench again and start again or just keep topping it up?
AUBREE – I am not particularly organized when it comes to feeding my trenches. Once the foundation (composting zone) has been established, I basically just add whatever I want, when I have it available. Food materials go underneath cover materials (which, as the name implies, just get layered on top). Straw is a nice cover material for keeping things looking tidy. Not 100% sure how you would incorporate trenches into the set-ups you’ve described – it IS possible with a raised bed, but anything smaller than that and you might be taking up too much planting space.
CHRIS – I have cleaned out one of my trenches on two separate occasions:
But I don’t usually do this at all. Most of my trenches have simply evolved into windrows. If you have the time and energy, excavation can be a great approach, since you’ll end up with lots of nice material you can use as a compost/mulch, and you’ll have loads of room in your trenches for more materials.
I have found that if you are keeping worms in the ground in a trench or bed.
A layer of flat cardboard boxes will shade the worm & they will eat the under side of the box.
I much my 20 blueberry plants with thick cardboard to keep down weeds & keep water in the beds in the heat of S.C.
WILD earth worms showed up under the card board, CB only last 2-3 year, but it is free.
You can over lay with leave if you like, but it is not needed.
Thank for a great site.
I save kitchen ‘green waste’ (including coffee grounds, egg shells, etc) in a coffee can under sink. When full I just dig a hole in garden and bury the contents. Been doing this for several years all seasons. Never added worms, native ones multiply fast. Improves garden soil a lot.
Will red worms die in your composting pile………..The inside is heating up. I turn the pile over weekly and feed and water. the dimensions are about 7 foot by 5 foot and 2 to 3 feet deep……..How long should I let these materials compost..?……….Does all the material have to be broken down before I use it………..?and should I use the material on the bottom first since this appears to be the most broken down?
I have 3 worms bins and one compost………getting ready to start a trench compost. I have a 5 gallon bucket……….a Rubbermaid tub and the Lg Rd Folgers Coffee can…………fun…….fun……..fun………..I like to dump the coffee can and the Rubbermaid to see how many worms I have. Does this disturb or stress the worms to much?
Thank you in advance
Peggylee, sounds like you’re doing it all correctly. The worms will migrate to cooler areas when it heats up in the middle, then come back once things cool down to their liking. You’ll know when the compost is ready to use because it will look like soil instead of food scraps, it’ll be nice and black and earthy smelling. Dumping the bins doesn’t harm the worms, they’re tough! They may migrate down away from the light, but that’s just what they do.
I was wondering how the trenches are doing now. All these years later how do you maintain them? Or do you? Do you still feed the worms in them?
Over time the trenches basically fill in and become windrows. Periodically I have excavated them (stuff I dig out is an excellent mulch) and started again. I have also dug completely new ones. So the long and the short of it is that if you plan to use the same trench over and over again, it is best to excavate it every 1-2 seasons.
Last season I mainly treated by big trench as a windrow, adding lots of aged horse manure and other foods to it during the growing season. Over the winter nothing happens with it so I need to add lots of rich stuff in the spring if I want to get it going again – otherwise the composting worm population will move on the greener pastures (more active systems I have going in the yard).
Do you have a problem with mice and rats using this method?
Define “problem” – haha. I’ve certainly had various rodents setting up shop in various outdoor systems over the years. None of them have created any real challenges or headaches for the most part, although for some reason this year the shrews finally seem to be having an impact on the worm populations in the systems they’ve invaded.
I have not had a problem with rats/rodents, because of compost or trench systems I have used. I have 10 acres, if you have only i acre or less then It could be a problem.
What do you do about wild animals coming from the smell ? Will it attrack a ton of critters ? Thank you
Hi Tracey – it is pretty important to be familiar with your own local wildlife situation and adapt accordingly. Different foods, and different management practices can vary widely in terms of potential for attracting critters. If you use “living materials” like well-aged horse manure, composted leaf litter etc, these can definitely help to mask odors – but even still my advice would be “it depends”. eg if I lived in bear country I would likely avoid ALL food wastes in a vermicomposting trench – or maybe experiment a bit with one that was far away from the house etc. Hope this helps.
I am going to grow mushrooms in straw & on logs.
Is there any system for reusing the waste with red worms?
Or should I just put the waste in a trench.
Awesome. I’ve been using this technique for many years now to build soils for raised beds here in central Texas. I call it “hugeling”. The only difference between your method and mine is that I use the method for building entire garden beds and also I incorporate directed composting methods to continuously build soils all year long. It works one of the many benefits of direct composting is that we grow volunteer plants like tomatoes, cantaloupe, peppers, sweet potatoes & potatoes–essentially without extra cost of buying plants. Quality is very good also. We do have a long growing season here though so that makes a difference I think. There’s a really good book by Sally jean Cunningham called “Great Garden Companions” that is very helpful for folks interested in learning organic gardening techniques and incorporating companion planting techniques also. I’ve been using many of Sally’s techniques for many years in my vege garden and have increased production without use of harmful chemicals. It works.
Thanks for sharing, Mary! Your name sounds similar to “Hugelkultur” – yet another cool subterranean decomposition strategy. More people should be doing all these sorts of things in their yards!
It seems to me that everyone who is doing organic gardening , is now doing vermicomposting. Or maybe everyone doing vermicomposting are gardening.
Now to get some honeybees.
I did something similar in my garden for years. As I removed things in the garden, like bolted lettuce, I dug a trench where they had been and buried them. Less waste.