Compost tumblers are like the stacking worm bins of the backyard composting world. There are countless models. They are heavily marketed. A lot of people use them.
So, we tend to get quite a few questions about them!
But, are they really as effective as many people claim them to be?
In this article we explore this interesting (and overdue) topic, with the aim of leaving our readers with a broader understanding - and perhaps a more flexible perspective - relating to compost tumblers and the best ways to put them to good use.
Tumbler 101
Compost tumblers are a type of composting bin designed to make turning and aerating compost faster and easier. The container is typically mounted on a frame or stand that allows for rotation, although simpler units can be rolled along the ground.
They come in a wide range of sizes, with commercially-available models ranging anywhere from 17 gallons (~64 L) up to 100+ gallons (~380+ L). Similarly, there is also a wide range of pricing - from less than $100 to nearly $2000 CAD.
These stats alone should help to highlight the fact that not all tumblers are created equal!
Let’s now look at some of the overall pros and cons of these systems:
Compost Tumbler PROS
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Wide range of makes and models available - These are one of the most popular types of composting bin, and there is no shortage of options when shopping for one.
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Quite affordable - There are plenty of budget-friendly tumbler models. Just keep in mind that with lower-priced models you also tend to end up with more “cons”.
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Usually lightweight and don’t take up a lot of room - Most tumblers are fairly compact in size and made of plastic or lightweight metal. This makes them easier to move around than typical backyard composters.
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Less labour; Better Mixing; Better Aeration - Unlike static systems, this is where tumblers really shine. The rotating process is what can make these systems easier to use and, in some cases, even more effective than other composting bins.
- Elevated Position Reduces (Some) Pest Issues - There is less chance of your compost bin being invaded by rodents and various other pests when it is sitting up off the ground. But this “pro” can also be a “con” in certain cases, as we will see below.
Compost Tumbler CONS
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Usually quite small compared to other backyard systems - This means reduced composting volume and heating potential.
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Very exposed - The lightweight design and raised position leaves tumblers even more exposed to the elements than many other backyard systems. This can also make them a more likely target for larger animals, such as bears (especially if you are using food wastes).
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Questionable claims - Compost tumbler marketing can often give people the impression that they will end up with perfect compost in less than a month. This is misleading at best, especially with the budget-friendly brands.
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Many models have poor drainage so materials can stay too wet - Even with adequate airflow, excess moisture can lead to anaerobic conditions, which greatly reduces the effectiveness of the composting process. This is more of an issue with smaller, cheaper models that can get over-filled more easily and have no drainage holes.
- Tumblers Are “Batch” Systems - Unlike many backyard composters, worm bins, and bokashi buckets - which offer the convenience of a more continuous process - compost tumblers work best when you put all your materials in at the beginning and don’t add anything new until the next cycle. This limits the amount of wastes you can process (especially with smaller tumblers).
Compost Tumblers for Backyard Composting
A big question on people’s minds is really just how effective these systems are for backyard composting. How do they compare to regular backyard composters like Earth Machines, or a GeoBin (for example)?
Volume, alone, is a very important consideration - and one that many (especially new) compost warriors fail to take into account.
Earth Machines are about 80 gallons (~300 litres)
GeoBins can be expanded up to 246 gallons (~930 litres)
Most of the popular models of compost tumbler are far smaller than even 80 gallons.
For context - the low-end (bare minimum) volume for actual, sustained “hot composting” is about 1 cu yard (764 litres - just over 200 gal). Realistically, many standard backyard composters on the market don’t provide this (the GeoBin being an exception) - but even most of the largest commercially-available (home-scale) tumbler models have less volume than an Earth Machine.
To compound this issue, many tumbler models have a dual-chamber design - meaning you are really only getting half the composting volume of the entire unit.
And then we get to price.
High-end compost tumblers - such as the Jora brand - do offer larger volume (but still not much more than 100 gal), better design, and higher quality construction. But, they aren’t cheap - with higher-end models being priced above $1000 CAD. It really comes down to asking yourself how much you are willing to spend to compost your wastes effectively?
As touched on earlier, where tumblers do shine is with mixing and aeration - and this is no small thing.
Typical backyard systems can be set up to support better aeration (especially the GeoBin, which is designed for good ventilation), but if you want to do any mixing, it will need to be done by hand. With tumblers, this process is very easy and effective.
Let’s now look at a couple of key ways the design perks of tumblers can be used to help with your composting efforts.
Compost Tumblers and Vermicomposting
Something a lot of people wonder about is whether compost tumblers can be used as worm bins. In some ways, it is natural to wonder about this - both of these approaches are promoted as effective composting methods, so why not combine them for even better results, right?
In reality, though, each approach tends to work better when operating independently.
Yes, technically, a compost tumbler could serve as a worm bin - if it was in an environment protected from extreme environmental conditions - but it’s not something we recommend. After all, there are plenty of systems far better suited for worm composting - and by using a tumbler this way, you would also be missing out on some of the key benefits they offer!
Worms thrive in systems with a limited amount of disturbance - and tumblers are literally designed for frequent disturbance! 😆
Those mixing and aeration perks of tumblers do make them highly effective for producing top notch worm food mixes, though - and this is how we recommend using these systems.
A simple combination of 2 or 3 parts "browns", 1 part living material, and 1 part "greens" is all you need to create a great food mix in 1-2 weeks. Unlike typical kitchen scraps and other fresh waste materials, this type of mixture is going to have a rich microbial population, and it will be partially broken down by the time the worms receive it - likely resulting in much faster processing in a regular worm composting system.
NOTE: Just keep in mind that food mixes made in outdoor compost tumblers should be used in outdoor systems - especially during warmer times of year - since there’s a good chance that the material will end up invaded by some form of flying pest (e.g. fruit flies, gnats).
Compost Tumblers and Bokashi
We’ve written about “Phase II” of bokashi - the critically important step that shifts it from a fermentation process to a composting process. The Soil Factory Method is a great way to accomplish this, but if you do happen to have a compost tumbler, it can offer another great way to get your bokashi “precompost” ready for regular composting, or even your garden.
Important Steps For Any Phase II method:
- Drain off as much excess liquid as you can from your bokashi bin (see the Phase II article link above for more info about what you can do with this liquid).
- Mix your precompost with enough bulky bedding and living material so as to balance the remaining moisture, greatly improve airflow, and integrate countless aerobic decomposer microorganisms into the material.
- If you happen to have some form of alkaline rock dust or our pH Buffer/Grit, mixing in some of this can raise the (typically very low) pH of precompost, helping to speed up the conversion process.
We’ve said it before, we’ll say it again…where tumblers really shine is in their ability to mix and aerate the materials - which is even more important in cases (such as this) where you are working with anaerobic starting materials!
DIY Compost Tumblers
Some readers will naturally wonder if they can make their own compost tumbler. The good news is that, yes, you absolutely can, and you don’t even need any real building skills to make a basic (but still functional) unit! More on this in a minute.
DIY Tumbler Perks:
- They can be less expensive
- You can create a custom design to suit your needs (this one is important)
Likely the most popular (and practical) way to make a DIY tumbler is to use some type of plastic barrel as your vessel (although, we recommend checking out this video featuring a cool DIY wooden tumbler design). Used barrels can often be obtained inexpensively - sometimes even for free - from local businesses or suppliers.
Just make sure your barrel: 1) is made with food-grade plastic and 2) was never used to store any type of harsh chemical.
On the “basic” end of the design spectrum, a barrel with some aeration/drainage holes could be a perfectly functional tumbler if periodically rolled along the ground. Adding plenty of holes on what is typically the “bottom” of the barrel, and leaving it in an upright position between rolling sessions, should even provide you with better drainage than many commercial models offer. Just keep in mind that you’ll likely end up with more organisms moving in from the surrounding environment (similar to most backyard composting systems - not something to be overly concerned about).
Anyone with some DIY skills may want to attempt a more advanced build. Some quick searches on YouTube will lead you to a whole world of possibilities on that front!
Our DIY Experience
PC’s “Worm Guru”, Bentley - who claims he couldn’t hammer his way out of a paper bag 😄 - built a DIY tumbler a number of years ago using a basic wooden frame and a food-grade plastic barrel mounted on wheels (no need for an axle).
Other unique design features - often not found in purchased models - included drainage holes in the body of the tumbler, and long nails that served as mixing “fingers”.
The tumbler worked very well as a “pre-composting” system - helping to prepare waste mixes for use in vermicomposting systems, but like many tumblers, the volume was just too small to allow for any sort of sustained “hot composting” process - and increased exposure to the elements reduced the length of its “season” in comparison to other backyard systems.
Tumbler Tips
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Be careful Not to Overfill Your Compost Tumbler - This is very easy to do with many models, and a key part of the mixing and aeration process is having enough space for the movement of the materials (and air). It mostly comes down to making sure there is some obvious air space in the unit (materials will settle and reduce in volume, which will help as well) rather than stuffing it to the brim.
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Err on the Side of More “Browns” - Moisture management and airflow are really important in a tumbler, especially one that doesn’t actually have drainage holes. Using lots of bulky, absorbent “browns” can greatly help us with this. Again, we’re recommending more of a “pre-composting” process with these systems - especially well suited for making mixes that can then be added to a worm composting system - so having a high C:N ratio is not going to be a problem at all.
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Aim for “Nice and Damp” But Not Soaking Wet - As in the case with any composting system, providing your tumbler materials with adequate moisture is very important for the breakdown process. The usual “wrung out sponge” level of moisture recommended for composting should work well. If you decide to water everything after it is added to the tumbler, just make sure you mix everything thoroughly, and then drain off any water still pooling in the bottom (even if your model doesn’t have drainage holes, the door typically lets liquid drain out when positioned towards the ground).
- Amendments Can Help - While not critical, various types of living material, rock dusts (like our pH Buffer/Grit), or biochar can help with the breakdown process, and leave you with an even higher quality mix for use in another system.
Final Thoughts
If there is a big take-away we want to leave you with here, it’s that most compost tumblers can serve as a fantastic composting tool - but not usually as a be-all-end-all perfect composting system.
We always promote a multi-pronged composting approach (involving our “Big 3” methods), and the good news is that tumblers can play a very valuable role in this approach when used strategically.
The tumbler design concept has some very strong points, there’s no doubt about it. When you can mix and aerate your composting materials quickly and easily - especially with the right mixes (including those microbe-loaded “living materials”) it’s going to have a significant positive impact on the breakdown process.
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We’d love to hear about your experiences with compost tumblers, and are more than happy to answer any questions you may have about this interesting topic! As always, please don’t ever hesitate to get in touch! 😎
Helpful Related Resources
What is “Living Material”?
Tips and Tricks for Worm Food Optimization
Bedding - The Most Important Material in Your Worm Bin?
Setting Up Your GeoBin for Worm Composting Success
Bokashi Phase II - Turning Your Pre-Compost Into Beautiful Black Gold
Recommended Products
GeoBin Composting System
Premium Bokashi Starter Kit
pH Buffer/Grit
BioChar
Effective Microorganisms - EM