Many people love the idea of turning their wastes into black gold, but aren’t quite as excited about keeping worms in their homes. Others - perhaps with a bit more of a worm-friendly attitude - don’t like the idea of having to spend time separating worms from their castings. While others are just looking for a “lazy”, cheap way to turn their organic wastes into rich, plant food.
Is there a system that checks off all these boxes?
There is indeed: the DIY in-ground bucket worm composter; in our humble opinion, one of the most underrated home-scale opportunities in vermicomposting!
DIY Bucket Vermicomposters At a Glance
- Small-scale, effective way to vermicompost outdoors.
- Inexpensive and simple to make.
- Fast and easy to install.
- Lightweight (even when full) and durable.
- Protective against the elements, and bigger pests/predators.
- Accessible to plant roots (with additional help provided by the worms)
- Space-saving and easily hidden.
Choosing Your Bucket(s)
There are a variety of buckets that can work for this type of system, but there are some important considerations to keep in mind:-
Size - 5 gal (19 L) buckets are a great choice because they are big enough to provide the worms with plenty of habitat volume, yet they are small enough that they shouldn’t take up too much space in a garden, and should also be fairly easy to lift/move even when completely full. Buckets in the 2.5 gal range could likely work quite well too, but you may find that they fill up too quickly.
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Durability - it is best to use a bucket with thicker, more durable plastic. Buckets with thinner plastic - such as those used for kitty litter - can work as well, but there is a much greater chance that they will crack and fall apart over time.
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Cost - one of the great things about (most) buckets is that they are very inexpensive, maybe even free. There’s no need for anything fancy; a basic 5 gal pail from your local hardware will likely be a great choice.
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Lids - Using a bucket with a tightly fitting lid offers a lot more protection from animals and the elements.
- Leaching Potential - it is best to choose a bucket that is “food grade” to help ensure that you won’t end up with any harmful chemicals leaching into the system or surrounding soil.
Supplies
- Bucket(s) - 10-20 L
- Drill with ¼” bit
- Sharpie and ruler - to help with hole spacing (optional)
- Bedding (eg shredded cardboard, hemp tow)
- Living material (eg finished compost, old rotten leaves, well aged horse manure)
- ⅛ or ¼ lb of Red Worms (or a supply of worm-rich material)
- Fruit/veggies wastes
- Watering can
The Worms - one of the great things about these bucket systems is that you don’t need a lot of worms to get them started. We actually don’t recommend starting with more than ¼ lb (or ½ lb max) of Red Worms. If you already have some other vermicomposting systems going, an excellent way to stock your bucket(s) with worms and living material is to simply transfer over worm-rich material from one of your active systems.
Preparing Your Bucket(s)
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Drill 8-12 holes in the lid. These are mainly for ventilation, but they will also let some precipitation in.
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Drill 12-16 holes just below the lip of the bucket (first ring on a typical 5 gal pail). You can drill holes in the other rings if you want, but this upper ring of holes will be helpful for additional airflow..
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Drill 12-16 evenly-spaced vertical rows of 8-10 holes in sides. You will want a lot of holes for the worms to move in and out, and to provide additional ventilation.
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Drill 20-30 holes in the bottom. These are the most important holes, since they allow for drainage (which will prevent pooling/flooding)..
NOTE: There is a lot of flexibility with the exact number of holes you drill in your buckets, and the numbers provided are just guidelines. The key is simply to have a modest number of holes in the lid and a lot of holes in the sides and bottom.
IMPORTANT: Make sure all your drill holes are free of debris and sharp edges (especially in sides and bottom), since we don’t want to harm the worms.
Choosing a Location
In-ground bucket vermicomposters can be installed in just about any location with soil access and relatively easy digging, but to maximize the benefits and effectiveness of the system, you may want to be a bit more strategic with your site-selection. A great spot to put these systems is in garden beds, fairly close to where you are growing crops or ornamentals. This way, the plants can benefit more directly from the activity of the worms. Garden sites also tend to offer the easiest soil to dig in. (We installed one of ours at the end of a long row garden)
Speaking of which…
You are best to avoid spots that have a lot of rocks or bigger plant roots, and any areas close to water bodies or where run-off flows or accumulates.
NOTE: When putting these systems in gardens, the easiest approach is to install them before you add any plants. If you are installing them in beds with established plants, be sure to space them far enough away so as not to damage the main root system.
Preparing The Site
How deep the system is buried is up to you, but it may have an impact on the level of protection you can expect, and the overall aesthetic appeal of the spot where you put it.
Our recommendation is to bury the bucket enough so that the lid is just above the soil surface, with the first row of air holes (just below bucket lip) exposed. It can then be covered with straw or some other mulch to add more protection and make it more inconspicuous.
Dig a hole that is about 6” deeper than the height of the bucket. This way you can add a nice thick false bottom below the system.
Make the width 1-3” wider than the bucket (on all sides). This will give the worms an extra habitat zone to move in and out of, and it will help you accommodate the handle as well.
NOTE: You may prefer to lay the handle on the soil surface instead (this may make it easier to pull the bucket out later on) - just keep in mind, the system may end up somewhat more exposed.
Add wood chips/mulch in the bottom of the hole. You will want enough material so that when the bucket (with lid) sits in it, the top of lid is about 1-3” above the soil surface.
NOTE: wood chips or mulch are a better choice than shredded cardboard (straw, hemp etc) for this zone, since they are resistant to breakdown, giving the bucket more stability and separation from the bottom of the hole while the system is in use. They will also aid with drainage.
Add the bucket, and make any necessary adjustments. You’ll want your bucket to be level and stable in the hole, and to be at the desired height.
Fill in the space around the bucket. You can use wood chips or mulches here, but more typical bedding/habitat materials, like shredded cardboard, hemp tow (shown below), fall leaves or aged bedded manure may be a better choice.
The Set-Up Process
With your bucket now positioned perfectly in the hole, it is time to get the system set up and ready to roll. It’s important to note that there is no one, “perfect” way to set up a system like this. But there are a few broad recommendations:
- Add a diversity of materials in fairly thin layers (other than the one exception mentioned next)
- Add mostly bedding (ideally with some living materials as well), with extra-thick bedding layers at the very bottom and very top.
- Add smaller amounts of food.
Let’s now explore the set up process in more detail.
Start with your false bottom. This will be a more-biodegradable false bottom than the one sitting below the bucket. Using 3-4” of shredded cardboard or “scrunched” brown paper is a great way to go. Over time, and nutrient-rich liquid drips down, this will become a very valuable worm habitat zone.
Add a layer of living material. Fairly stable, microbe-loaded materials like finished composts, leaf mold, and well-aged livestock manure (from a farm or stable, not a garden centre) can greatly improve the overall habitat quality for the composting worms and help to accelerate the breakdown process.
Add water-rich food materials. Fruit and vegetable scraps (or a pulp like you see in the image) are a great choice as “greens” in a system like this. They provide a lot of nutrition for the worms, as well as helping to maintain a moist environment inside the bucket.
Sprinkle in amendments (optional). If you happen to have rock dust, oyster shell flour (or some of our pH Buffer Grit), biochar etc, feel free to lightly sprinkle some in with your food layers.
More living material. Adding LMs directly over kitchen scraps ensures you end up with loads of microbes, exactly where you need them.
Add your composting worms. This assumes you are using bulk worms from a supplier - ideally ⅛ or ¼ lb (no need to add more than that, as touched on earlier).
In the case of stocking your system with worm-rich material from existing systems, you can simply substitute it in for the “living material” mentioned above.
NOTE: Some may wonder if you can skip the worm-stocking step, and simply let local worms move in and help with the process. This is perfectly fine, especially if you happen to have some active outdoor vermicomposting systems nearby, but you should be prepared for a slower composting process. Composting worms, like Red Wigglers, are much more specialized for processing rich waste material than your typical “garden varieties” of worms, so they will convert the bucket contents into rich castings a lot more quickly.
Continue the layering process. Alternate different habitat and food materials up to within ~3” of the bucket lip.
NOTE: Any layer directly above a worm zone should either be bedding or living material and, just generally, food layers should always be sandwiched in between bedding and/or living material.
Add your cover bedding. Top up the system with some lightweight, bulky bedding, such as shredded cardboard, hemp tow or straw (we used some older straw, shown below). This will help the system retain moisture, and balance future food deposits.
Add water. With a free-draining system like this, there is very little risk of ending up with conditions that are “too wet”, so it is a good idea to give the materials a thorough watering once everything has been added.
Ongoing Maintenance & Troubleshooting
DIY in-ground bucket worm composters are not only easy to set up, they’re also easy to operate. Even easier than a typical home worm bin, in fact! You can leave them to sit after the set-up process for 5-7 days before adding any new material. By this point the level will more than likely have gone down by several inches, due to settling and the feeding (etc) activity of the worms.
Adding New Food and Bedding
New food and habitat materials can literally be added as often as there is room to accommodate them. Unlike a typical, indoor worm bin, it is very difficult to “overfeed” one of these systems (although, you may want to err on the side of caution in remote areas with a lot of animals, since you may attract some if you add too much food).
The process of feeding is really just a matter of adding a layer of food on top of the previous cover bedding, maybe adding some living material if you have some, and then topping up with more bedding. If the level of material hasn’t gone down all that much, you can also simply add some food under the current cover bedding (ideally topping up the rest of the way with new bedding).
Green yard wastes like grass clippings and smaller weeds can also be added to your bucket systems. Just keep in mind that they may not get broken down by the worms as quickly kitchen scraps and other types of food.
Just a friendly reminder that adding small quantities of amendments like rock dusts or biochar - if you have them - when you feed can help to enhance the process, and end products, as well.
Some Potential Challenges with In-Ground Bucket Systems
Drying Out - Buckets, by design, are very good at moisture retention, and having the system in the ground will further assist with keeping everything moist. There may, however, still be times when excess moisture loss can create some issues (see the next entry for a prime example). We recommend keeping an eye on the contents regularly, especially during the heat of the summer, and don’t ever be shy about watering if it seems on the dry side. This can actually be a great “slow release” watering method for your garden, especially if you have multiple buckets installed.
Root Invasion - Plant roots naturally seek out moisture and rich sources of nutrients. Your in-ground bucket systems will be offering both. If you have installed one or more of these systems close to water-loving crop plants like tomatoes and cucurbits, you may find that the worm habitat ends up getting a bit choked out with roots, which can also dry it out quite a bit. Unfortunately, this isn’t really something you can prevent, but creating the bedding zones outside of the bucket, as described earlier, can at least ensure that your worms will have habitat options if the contents of the bucket ends up full of roots.
Pests and Predators - One of the great benefits of these enclosed bucket systems (especially in comparison to open systems like “Worm Towers”) is that they offer a lot of protection from various pests and predators. Firstly, it’s important to note that we’re talking here about larger organisms - not household “pests” like fruit flies, which will be inevitable in all outdoor systems, where they thankfully shouldn’t annoy us at all.
Open, outdoor vermicomposting systems can be invaded and otherwise compromised by various vertebrate organisms, such as mice, shrews, and robins - but your buckets should keep them all at bay. Larger mammals, like racoons and bears (in more remote locations) might pull your buckets out of the ground and attempt to access the contents, but likely only if you are adding a lot of kitchen wastes without much bedding or living material. Well managed in-ground bucket systems won’t likely attract these animals in the first place.
To Harvest or Not to Harvest?
Some people will naturally wonder how and when castings should be harvested from in-ground bucket systems. The good news is that, technically, you don’t really need to harvest castings at all, if you don’t want to. This is the beauty of integrated vermicomposting; the worms and microorganisms break down the waste materials, producing rich castings that the plant roots can access directly.
If your system isn’t sitting close to plants, and you are simply using it as an outdoor worm bin, feel free to harvest castings after 3 or 6 months - or once the bucket is mostly filled with dark, rich compost
End of Season System Removal / Resetting
In cases where you are indeed using these in-ground bucket systems to add fertility to your gardens, once the growing season is over, you will likely want to pull out the buckets and empty the contents into a backyard composter or some other active system (ideally, a system actually set up for vermicomposting).
If you would like to keep some worms going during the colder months of winter (NOTE: we are talking here about keeping worms alive, not keeping an active system, in most locations), you may want to simply reset the system. This can be as easy as dumping out the contents (as described above), and then just starting the bucket over again. Or, if you want to use some of the same worms, you may want to do a basic “light harvesting” approach to concentrate them into a worm-rich material that can then be used to stock the new system.
The earth itself (and any snow cover you happen to receive) will provide excellent protection in many locations, but we recommend you go the extra mile - especially in colder climates - by heaping lots of bedding materials, such as fall leaves, straw/hay, or woody mulches over top of the buckets.
Final Thoughts
DIY in-ground bucket vermicomposters are one of the easiest ways to vermicompost outdoors while boosting the fertility of your soils! They are very inexpensive to get started, a breeze to use and manage, and the results - healthy, vibrant plants - will speak for themselves. We highly recommend you install one or (even better) more of these systems this season!
Helpful Related Resources
The Plastia In-Ground Worm Composter
Can I Add Red Wigglers to My Garden?
Outdoor Vermicomposting 101
What Is “Living Material”?
Bedding - The Most Important Material in Your Worm Bin?
Recommended Products
Red Wigglers
Urbalive In-Ground Worm Composter
GeoBin
pH Buffer Grit
EM Concentrate