Outdoor Vermicomposting 101

Outdoor Vermicomposting 101

This is Part II of a 2-part backyard vermicomposting series. Be sure to also check out Part I: Can I Add Red Wigglers to My Garden?

When many people think of vermicomposting, they envision setting up some form of small to medium sized indoor “worm bin”, adding their fruit and veggie scraps to it, and eventually removing rich worm castings they can add to their gardens and potted plants.

This is a great approach - and having this smaller-scale, indoor composting option year-round is indeed one of the amazing things about vermicomposting!

But we’re here to tell you that it’s ok to think “outside the bin” every now and again! When you start exploring the wonderful world of outdoor vermicomposting, we think you’ll be pretty blown away by the potential and, even more importantly, the results that are possible!

Key Recommendations

Before we explore different outdoor system options, it’s important to cover a few universal recommendations we have for outdoor vermicomposting in general:

1) Set up outdoor systems in shady, well-sheltered spots, away from water bodies and potential hazards - outdoor environments are a lot more unforgiving than what you’ll find in your home, so every little bit of protection helps!

2) If possible, create a below-ground zone for all your outdoor systems. The earth has an amazing ability to protect a system from extreme conditions - helping to keep it warmer during cold weather and cooler during hot weather. In some regions, this can literally mean the difference between keeping your worms alive and having them die off each season. NOTE: If you are in a location where you can't dig down, you should be able to create a similar effect by mounding up a lot of soil and/or other materials (eg wood chips) around your systems.

3) Think in terms of 3 key zones - all of them bedding-heavy. The lowermost is your "false-bottom", where you can really pile up bedding materials, such as wood chips and coarsely ripped up cardboard. Next is the main worm composting zone, which should combine moistened bedding, with living materials, food materials - and of course your worms (which can be added down towards the bottom, either in bulk or in the form of a worm-rich material from another system). Lastly, it is very helpful to have a dedicated cover zone as well, where lots of loose bedding materials like straw and hay can be heaped up to provide your system with lots of extra protection.


Outdoor System Options

Some readers will naturally be wondering if they can simply set up (or move) a regular worm bin outdoors? This can work fine during milder times of year, but this definitely isn't the sort of "outside the bin" approach we alluded to at the start of this article! ;-)

Here are some 3 simple options that will help you take your outdoor vermicomposting game to the next level:

In-Ground Bucket Systems

In Ground Worm Composting With a Bucket

These are one of the easiest outdoor systems you can set up - and they work great too! A lot has been written about "Worm Towers" - basically, half-buried PVC pipes set up for vermicomposting. Well, we're here to tell you that buried bucket systems are not only much easier to set up and work with - they're also more effective! The worms have a lot more space to spread out in (and we have more space to add our food materials) - plus, it's a much more self-contained system. This means it is better protected, and can be removed/moved much more easily.

You can get an in-ground bucket system set up in a matter of minutes!

  1. Dig a Pit - How deep depends on whether or not you want your system to be visible. For a more inconspicuous approach, make the hole deep enough so that the bucket with lid can sit 3-4" below the soil line. Make it somewhat wider than the bucket to provide some air space between the system and the surrounding soil (we can fill this with loose bedding to make it easier for the worms to move in and out.)

  2. Adding some bedding in the bottom of the hole gives the worms another nice outer zone they can hang out in during more extreme conditions. It also provides some separation from the bottom of the hole. Wood chips can be a good choice here since they will take a lot longer to break down (helping to keep the bucket elevated, in case water starts to accumulate in the hole).

  3. Drill lots of 1/4" holes in the lower sides and bottom of the bucket. Make sure they are free of debris and sharp edges, since the worms will likely be crawling out and in.

  4. Place the bucket (without lid) in the hole and start with a layer of bulky, absorbent bedding such as shredded cardboard. This can take up as much as 1/3 the volume (don't worry, everything is going to settle, so it's not as much as you think).

  5. Above the false bottom, add some rich living habitat material like rotten fall leaves or aged, bedded horse manure, along with a small amount of easy to break down fruit/veggie wastes and your worms (either straight from the supplier's bag, or in the form of worm-rich material removed from another system).

  6. Layer different bedding and living materials - along with small amounts of amendments like rock dust, if you have them - all the way up. Feel free to add a bit more fruit/veggie waste up near the top as well, and cover with loose bedding such as hemp tow, straw or shredded cardboard.

  7. Water well with a watering can (no need to worry, since excess will drain away), and snap on the lid. NOTE: Using one or more fine screen holes (or vents) in the lid can help keep excess dirt and debris from falling in.

  8. Covering the (enclosed) systems completely with wood chips or straw or some other loose mulch can provide additional protection while keeping the buckets hidden from view. (Optional)

PRO TIP - Installing your bucket systems close to growing plants is a great way to naturally fertilize them as well!

Plastia In-Ground Worm Composter

Plastia Urbalive In Ground Worm Composter

Those of you looking for a more ready-to-go in-ground option may want to consider Plastia’s Urbalive In-Ground Worm Composter. The compact size (12 L) coupled with an attractive design make this a great choice for a wide range of garden locations. If you’d like to learn more, be sure to check out our blog post about this system.


Vermicomposting Pits and Trenches

Worm Composting in a Trench or a Pit

One of the simplest approaches to outdoor vermicomposting involves digging a pit or trench and setting it up like a worm bin (using our 3 zone approach). Start by lining the bottom of your holes with plenty of ripped up cardboard and/or other bedding materials. Next, add some moistened, safe habitat materials (living materials and/or bedding), along with a small amount of food and your worms. Then, continue laying in different bedding, living material and food layers (watering as you go) all the way up to soil level or just above (if you have some amendments like rock dust, these can be lightly sprinkled in as well). Lastly, add a nice thick layer of loose cover bedding, such as straw or hay.

New deposits can then simply get laid in just under the cover layers (or on top of the old cover layers, with new cover materials then being added after).

Backyard Composters for Vermicomposting

Earth Machine Composter

Many people overlook the amazing potential of using regular backyard composters for vermicomposting! The key is to set them up in a way that best supports the worms.

  • Yep, pretty much exactly the same basic approaches we've been outlining above.

  • Start with a pit down below the bin (make sure it is narrower than the lowermost width of the composter).

  • Add a false bottom with bulky/absorbent bedding materials.

  • Layer in your different habitat and food materials (with major emphasis on safe bedding and living materials), plus any amendments you happen to have.

  • Remember to add your worms down towards the bottom, and make sure to moisten all your layers as you go.

  • Add a thick cover bedding layer (eg straw, hay etc) up top.

What About Compost Tumblers?

A question commonly asked is whether or not compost tumblers can be used for outdoor vermicomposting.

The short answer is, technically, yes - but, ideally, no.

A tumbler sitting in a very sheltered location, during milder (not hotter, not colder) times of year could theoretically be used as a sort of worm bin - but we feel this defeats the specific purpose these machines were designed for! Worms do best when they are mostly left alone, so, basically, you'd need to avoid doing any actual tumbling. You may encounter airflow and drainage issues, And, you'd likely find it more challenging to work with the system (they typically only have a single, small door for access).

One way we feel you can effectively use tumblers to benefit your vermicomposting efforts is for food mixing and pre-composting, as well as habitat preparation. These systems are designed for mixing, so they can be really helpful for getting materials ready for a vermicomposting system!

Final Thoughts

There is certainly plenty more that could be said about the outdoor vermicomposting systems described above, but you should at least have a decent handle on the fundamentals of getting them set up and ready to roll! Stay tuned for upcoming in-depth articles about these, and other, outdoor options, and be sure to peruse our Helpful Resources section (further down) for our current line-up relating to this topic! If you haven’t already, you may also want to check out Part I in this series: Can I Add Red Wigglers to My Garden

Helpful Related Resources

The Plastia In-Ground Worm Composter
Fall - A Great Time to Get Your Backyard Composter Going!
What Is “Living Material”?
Bedding - The Most Important Material in Your Worm Bin?

Recommended Products

Red Wigglers
Urbalive In-Ground Worm Composter
pH Buffer Grit
EM Concentrate


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