Choosing the correct bedding for a worm composting bin is a high-consequence decision for a new vermicomposter. Choose wisely and be patient, and you’ll be off to a great start recycling organic waste into worm castings, and before you know it, it will seem like you’ll be able to do no wrong.
If you choose poorly and get impatient with preparing your bin, you’ll find that the worms will attempt to leave your bin as quickly as you put them in there. It will be a waste of money and, worse yet, you may get discouraged with the idea of worm composting and just decide to throw your kitchen waste in the trash like pretty much everyone else does.
This article will cover common types of bedding material that you can use in your bin, to include the pros and cons of each. At the end, I’ll give you some final thoughts.
This article is part of a “Vermicomposting 101” series of posts aimed at helping the beginning vermicomposter. The read other “VC101” articles on how to start a worm bin, how to choose worm food, how to maintain moisture, and the differences between composting and vermicomposting, please visit the Vermicomposting 101 section of this site!“
What is Worm Bedding?
Bedding in a worm bin is considered to be a ph-neutral organic material consisting of high carbon-to-nitrogen (C:N) ratio. Once high-nitrogen food waste is present, the high levels of carbon help to slow down the rate of decomposition and give microbes a food source while they decompose the nitrogen-rich foods in a worm bin.
The microbe part is important! A high-carbon substrate is a necessary, but not sufficient habitat for composting worms, who will be seeking a diverse ecosystem of not only bedding, but microbes (aka microorganisms), and at least some nitrogen sources in order to acclimate.
What Should I Choose for Worm Bedding?
At least initially, your choice of worm bedding will most likely be influenced by whatever happens to be your most convenient source of carbon-rich material. For most households, the most easy-to-find source of worm bedding will be paper and cardboard, which will need to be shredded and soaked.
And while it seems preferable to choose a worm bedding that you can procure from your own household waste, it may not be the best choice for ensuring you get off to a good start with vermicomposting.
Aged Horse Manure
Aged horse manure is an excellent choice of bedding for a worm bin. It can be ready-to-use dual-purpose bedding and food source for worms and is normally free. But give thought to the transportation hassles, permission from farm owners, and any deworming medications which might be present in the not-so-well-aged stuff.
- Often has a low enough C:N ratio that it can serve as a food source as well as bedding.
- Normally free to procure from any horse farm.
- May require no addition of water.
- Not readily available, especially in an urban environment
- Requires the consent of the horse or farm owner.
- Can be heavy, and requires transportation for most household worm composters.
- Horse deworming medication may be present in fresher manures and could be toxic to the worms. However, deworming medication is broken down reasonably quickly by sunlight and a pile of aged horse manure should be considered safe, especially if it is teeming with worms!
Shredded cardboard, especially of the corrugated variety, is a very common bedding source for most residential vermicomposters as more cardboard is delivered to a single home in the form of Amazon boxes than could ever be consumed by the worms. But improper preparation can create some hassles at harvest time.
- Free and in great supply.
- Dry cardboard can be a good way to regulate water content as it can absorb excess moisture.
- Microbes and worms readily colonize the corrugations, the little wavy parts in between the layers of paper.
- Need to be shredded and saturated with water if starting a new bin. Dry cardboard can be used in existing bins, however.
- If not shredded throughly, cardboard can create matting and slow the decomposition of the cardboard, which might make separating worms from the worm castings difficult.
Like cardboard, paper is in high supply in most households, offices, and schools. However, paper tends to clump and get matted during the vermicomposting process, ultimately creating a mess during harvest time. While plenty of online resources suggest not using colored, or glossy papers, most inks today are soy-based and will not be harmful to the worms.
- Free and in great supply.
- Shredded newsprint breaks down easily and will create a relatively homogenous bedding in a short time.
- Paper is also a good way to regulate moisture in an existing worm bin
- Like cardboard, paper needs to be shredded and saturated with water if starting a new bin.
- Paper can also cause matting in the sub-surface areas of the bin.
Some composts can be a wonderful starter for a worm bin as it is normally free and often (but not always) colonized by microbes. Large-scale vermicomposting operations “pre-compost” organic waste, so the idea is well-established. Composts, especially with leafy or woody material often promote a more fungal vermicompost.
- Normally free!
- Often already colonized by microbes.
- May be more difficult to procure in an urban environment.
- May include critters that, while most likely harmless, may not be welcome in an indoor environment.
Coco coir is a popular substrate among first-time vermicomposters. Made from coconut husks, coco coir helps create a clean, nice-looking homogenous bedding that will appear to break down quickly. But purchasing worm bedding is probably not necessary and coco coir must be rinsed to reduce salt content. It will also need to be colonized with microbes by adding small amounts of organic waste in order to be hospitable for worms.
- Is clean and requires no messy trips to the compost yard or horse farm.
- Creates a bedding that is good looking and homogenous in texture.
- Often has a salt content that may be noxious to the worms, so it should be rinsed before being introduced to the worms. This information is normally included on the label.
- Coco coir will be sterile initially until colonized by microbes.
- Must be purchased, possibly negating the environmental benefit of using an organic waste due to transportation costs, especially since nearly all coco coir is imported.
Similar to coco coir, peat moss is a clean-looking, consistent high-carbon bedding. But peat moss is acidic, non-renewable and again, it may not be necessary to purchase your worm bedding.
- Looks great and new vermicomposters will be confident in using it.
- Easily found in garden centers in both rural and urban environments.
- Has a low, sub-5 pH and may need to be mixed with other substrates to create a good worm bedding.
- Peat moss is considered a non-renewable resource, most likely imported from Canada and the methods of “mining” it are not considered sustainable in some circles.
Straw, not to be confused with high-nitrogen hay, is easily procured in rural and suburban areas. While it allows for airflow, it does not retain water well and should be used with another bedding material for best results
- Free or at least inexpensive
- Is a great “bulking agent,” allowing air to enter various levels of the vermicompost, keeping it aerobic.
- Promotes a fungal vermicompost
- Does not retain water well.
- Not easily procured in urban environments.
Leaves, Yard Waste, and Wood Chips
Leaves, yard waste, wood chips or a mixture of all the above can be a wonderful source of worm bin bedding, especially for a fungal vermicompost. Care should be taken that green yard waste like grass should be composted to raise the C:N ratio.
- Woody material is an excellent habitat to promote the growth of beneficial fungi.
- Will often be a ready -made habitat for worms due to existing ecosystem of microorganisms
- Any green yard waste should be composted and possibly examined for pesticides and herbicides.
- Will introduce non-worm critters into the bin, which isn’t really a con but may be unwelcome to the new vermicomposter.
- Worm castings harvests will include plenty of unprocessed material.
Your worm bin will not fail because you did not provide enough food.
It will fail because you did not provide adequate bedding or prepare your bin sufficiently before introducing the worms.
So, my ambitious vermicomposter, before I release you into the wild to gather your worm bedding, let me leave you with some final thoughts.
A Mixture of Worm Beddings is Wise
Don’t just choose one of the above beddings and say “that’s it.” A diverse mix of bedding is most likely the safest choice as you could get a few things wrong and not screw the whole thing up. Increase your chances of success by giving your worms a diverse habitat, just like they enjoy in nature.
Patience is Key
I counsel new customers of the Urban Worm Bag to take time preparing their bin, taking as long as a week or two to allow the bedding and moisture to stabilize and to add a small microbe-blooming organic material like food waste to the bin, well before the worms arrive. I lost over $100 in composting worms by not taking this advice when I began.
Start with Existing Vermicompost if You Can
If you’re not cheating, you’re not trying.
By starting with existing vermicompost, you are greatly increasing your odds of success since you’re starting with a proven substrate. A worm bin is like a fire; it’s much easier to keep one going than it is to start from scratch.
This dovetails with the advice to mix up the beddings as well. If you start with existing worm compost and one of the choices above, it is going to be a diverse habitat. And a successful one too.
You Don’t Need to Buy Worm Bedding, But……..
It is not necessary to purchase a carbon-heavy worm bedding with which to start your worm bin. Full stop.
And once you get going with vermicomposting, the idea will seem silly.
But you have the blessing from the Urban Worm High Priest (that’s me) to go ahead and buy it if doing so makes your foray into worm composting in the home, school, or office a little less intimidating.
The purists are going to hate me for saying this, but if you want to do this and don’t have a shredder, don’t have access to leaves or compost, or don’t want to ask a farmer for horse poop, then by all means, buy your bedding. (Hint: I recommend coco coir!)
Never Stop Learning
Always be a skeptic and be willing to question everything, including the “wisdom” in this article. There are a lot of conflicting sources of information and this is one of them. (Heck, you’re going to find conflicting guidance on this very site as my own views have evolved over the past 5 years.)
My guidance is just that….guidance. And it should not be taken as gospel.
If you liked what you read here, I invite you to join my e-mail list below and read the rest of my Vermicomposting 101 Series.