Gardening with Composting Worms

June 13, 2013

One topic a lot of people seem interested in is that of using earthworms to add fertility to lawns and gardens. Unfortunately, many assume that you can simply dump a bunch of composting worms (or even soil worms for that matter) on the lawn or in the garden and they will miraculously transform lifeless soil into an oasis of nutrient-rich, loamy goodness! What’s perhaps even more frustrating is the fact that there are disreputable worm sellers out there – knowing full well that this is not a viable approach – who are more than willing to sell their worms for exactly these applications (thus helping to spread this misinformation even further).

Well, the good news is that not all hope is lost! There are in fact ways to create worm-rich soils and even integrate composting worms into a typical backyard growing environment. If I might borrow a famous line from the movie, “Field of Dreams”…

If you build it, they will come (or in the case of composting worms – ‘…they will STAY’)!

So what is it that needs to be “built” exactly?? Some sort of rich, earthworm habitat.

If you provide the worms with what they need to survive – or better yet, THRIVE – they will be more than happy to help you create beautiful, rich organic soil!

In the case of soil worms, assuming you live in a region where there are some native species, this should simply be a matter of adding lots of lots of organic matter to your soil. Materials like composted/aged manure, fall leaves, grass clippings, even cardboard can all help. I’m not going to claim that the worms are going to appear overnight (although in some regions it may in fact happen pretty quickly), or that the soil is going to be transformed in a matter of days, weeks, even months – but if you work at it, and you don’t mind being patient, you could likely see some major improvements during a single growing season. Even more so over the course of several years.

IMPORTANT NOTE: If you don’t have native soil worms in your region, it is NOT recommended that you add any purchased from bait dealers etc. It has been shown that various soil species, such as Canadian Nightcrawlers (Lumbricus terrestris), and semi-soil species like Lumbricus rubellus can have a negative impact on forest ecosystems in regions where they are not already well-established. The good news is that there is no evidence that composting species (Eisenia fetida/andrei or Eisenia hortensis) pose any threat. Some researchers (including one I personally communicated with) believe this has to do with a lack of cold tolerance in these worms. My own opinion (supported by another earthworm researcher I contacted) is that this is actually due to the fact that these worms are specialized for life in very rich organic materials – such as that found in manure and compost heaps. They are NOT leaf-litter-processing worms.

If you don’t want to wait quite so long for a positive impact and/or you’re in a location that may be sensitive to invasion from soil species, you MAY want to consider various ways you can integrate composting worms into your outdoor growing environment. Here are some approaches I have tested (or are in the process of testing) that seem to offer a lot of promise.

Vermicomposting Trenches & Pits

Back in the spring of 2008 I (naively) decided to start accepting compostable food wastes from a very popular local restaurant. This amounted to 100’s of pounds of material I needed to pick up (and bring home) each week.

It’s safe to say that my optimistic-enthusiasm was writing cheques my backyard couldn’t cash!

Long-story-short, after filling up all my outdoor systems, and digging holes all over my property so I could bury the wastes, I started to realize I was in a bit of trouble! The overloaded composters, and various other “temporary” storage bins were starting to stink REALLY badly! In an act of desperation I decided to dig a giant trench alongside one of my gardens. Initially the idea was simply to dump everything in and bury it with soil – but thankfully I ended up with a better idea. I decided to basically set up the trench like a giant worm bin to see if composting worms could help me to process all these wastes I was receiving.

As you might imagine, these trenches (I added more over time) ended working very well. Not only was I able to continue receiving (and processing) the restaurant wastes for the rest of the summer, but the growth of my garden crops absolutely exploded that season. It’s safe to say that the experience has completely changed the way I think about outdoor vermicomposting (and gardening)!

If you are in a location where setting up a vermicomposting trench is a viable option, I highly recommend giving it a try. You may just end up as blown away with the results as I’ve been!

For more information about vermicomposting trenches, be sure to check out these articles (on Red Worm Composting website – will open in a new window):
The Vermicomposting Trench
Vermicomposting Trenches Revisted

Vermi-Fertilization Hubs & Worm Towers

What’s interesting (looking back now) is that my original plan for the restaurant waste vermicomposting project had been to set up a series of in-ground bin systems using plastic garbage cans. For whatever reason (I can’t recall now) I decided not to go ahead with that idea, and that approach in general has sat on the backburner ever since.

Until last week, that is!

I decided it was finally time to test out this approach for processing wastes, and fertilizing plants! So I set up one of these bins in the middle of a small raised bed garden. Some would definitely claim that this is a big waste of space, but the fact is, I only ever planned to put 4 tomato plants in that garden anyway, so I think this was as good a location as any for testing this system out – and I’m very excited to see what this thing can do!

If you’d like to learn how I created and installed this bin, be sure to check out this article (on Red Worm Composting website – will open in a new window) : Vermi-fertilization & Watering System.

Another similar approach I later learned about is known as the Worm Tower. Here is a YouTube video that shows you how to make one.

This is another approach I have been meaning to test out for quite some time now – and this year I’m finally gearing up to do so!

I purchased a 10 foot length of 4″ PVC drain pipe (white stuff that already has holes in it) and cut it into 2 ft lengths (actually slightly shorter to compensate for the one flared end). I also got some 4″ pipe caps as well.

I have yet to install any of these (rest assured I will write about it here when I do), but the basic idea is to bury these lengths of pipe in the ground – in close proximity to growing plants – and to fill with bedding and food wastes (among various other options). You don’t HAVE to add composting worms (since soil worms will likely invade these as well) but they are ideally suited for this sort of approach and will greatly help to speed up the process of converting the wastes into beautiful “black gold” for the plants.

UPDATE: As much as I love the Worm Tower concept, unless you can find a pipe with a decent diameter (or simply use something like a bucket or garbage can), the volume is just going to end up being too limiting. These smaller ones can still work well-just be prepared for them filling up fairly quickly.

One other similar idea I’ve started to test out recently is my pet waste vermicomposting system (RWC site – opens in new window). I wouldn’t set up a bin like this close to where food crops are growing, but it can be a great way to fertilize shrubs, ornamentals etc, or even dynamic nutrient accumulators such as comfrey (image in backyard composting section below shows how well one of my comfrey plants is doing), which can then be used for a variety of other composting/fertilization applications.

Vermi-Mulch Gardens

Another vermi-gardening approach that can work well – and one that’s even easier to implement – is what I’ve referred to as the “Verm-Mulch” (or “Garbage Gardening”) method. The basic idea is that you create a rich composting worm habitat zone up above the soil surface, and introduce composting worms to that.

While these beds may be easy to set up, the trade-off is that they can require more attention during the growing season since they are more exposed to the elements. It’s important to continually add water-rich food materials and/or soak down regularly. As I’ve discovered, the plants alone can take a serious toll on the moisture content of these beds (with their roots growing right through them), so when you end up with a hot dry summer as well – they can become next to impossible to maintain.

Still a viable approach to consider, though!

I should also mention that simply adding lots of rich organic matter, like aged manure and/or food wastes to raised beds and planters can help you sustain a population of composting worms in them. My only warning here would be to make sure you water them thoroughly before adding the worms if using bagged soils to fill them (these can sometimes contain starter fertilizers which can harm or kill the worms). Also be sure to use only organic-based gardening methods.

Regular Backyard Composters

Most people would likely think of backyard composters as something completely separate from their gardens. The idea is usually to add wastes and then, months later, harvest compost that can then be used elsewhere. This is a perfectly fine strategy (and I recommend you check out “Backyard Composting with Worms“), but if you choose the right location for these bins – ideally close to where you’ll be growing plants – you can add a serious boost of fertility without the hassles of compost harvesting!

Manufactured bins (such as the “Earth Machines” in the image above) are very easy to set up – again, I recommend reading my other article on setting up a backyard composter for vermicomposting, linked above – but if you take more of a DIY approach and get creative with the design of these systems, the sky is the limit in terms of the integration possibilities!

There are a wide variety other ways to use composting worms into your backyard gardening (or even farming) systems, but hopefully I’ve at least given you enough to make you want to learn more, or better yet – feel the urge to try out one of these cool vermi-gardening strategies!

Please DO share your own experiences/plans here in the comments section! Rest assured, I will also keep everyone posted on my own vermi-gardening (and related) projects this year!