There are many types of bedding material that is suitable for vermicomposting systems. This discusses the pros and cons of some the common bedding types.
Before I dive deeper into this, it should be noted that the bedding material is really the most important part of the system excluding the worms. Bedding provides worms the habitat they live in and provides them areas to go while food scraps are breaking down. Some general characteristics of a good bedding material are:
- Holds moisture – most sites and videos will indicate that bedding should have a moisture content similar to a wrung out sponge. I recommend one actually wrings out a sponge to get an idea!
- Absorbent – really same as above but the material should be able to absorb excess moisture from the food scraps
- Act as a filter – what I mean by this is that bedding added on top of food scraps should be able to prevent any unpleasant smells. One of the quickest ways to stop vermicomposting indoors is to get a whiff of rotting broccoli…trust me it’s awful
Here are some of the bedding materials used:
Although this is a dwindling resource with newspapers decreasing production, newsprint is an OK source for bedding. Most inks nowadays are non toxic and work fine. However, glossy inserts should be avoided as they tend to contain some plastics such as BPA. Newsprint isn’t my favorite source as I find it annoying when it mats down. Also, it can dry out pretty quickly which requires adding water to bins to maintain a good moisture level. However, the worms will work through it reasonably quick.
- Available almost everywhere
- Easy to shred by hand
- Absorbs moisture well
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- Tends to mat down and can inhibit airflow
- In continuous flow through systems it has a tendency to dry out along the sides
- Doesn’t filter smells all that well
Cardboard / Egg Cartons (pulped paper)
Cardboard and Egg Cartons are one of the best sources for bedding. It is readily available with all those Amazon shipments one gets and it provides a good balance between holding moisture and allowing airflow. The center of corrugated cardboard provides an air pocket which can help with airflow. The glues that hold corrugated cardboard together are non-toxic
- Readily available
- Provides good airflow
- In general the worms really favor this material – this is based on personal observation
- Can retain moisture well after it has soaked in water
- Requires some effort to make it suitable – either soaking large pieces in water, putting it through a shredder, etc
- Some cardboards contain a wax coating that resists moisture – this should be avoided
- In flow through systems it can dry out
- In bin systems it can mat toward the bottom of the bin
Office paper can be very readily available for one that works in an office. Most offices have a paper shredder and can provide an easily accessible bedding source. I would caution that this material should not be the sole source of bedding. The inks in office printers may not be appropriate for use in a worm bin. There is also some conflicting information out there on whether there is any bleach remaining in the paper. I have not researched this aspect so I cannot give an opinion on that. However, my observations with the material is that the worms will tolerate it but it is not their favorite. In a bin with a variety of bedding materials this tends to be the last one consumed.
- Readily available
- It does offer a way to reduce waste – in the late 2010’s recycling in general has declined due to the virgin materials being cheaper and contamination
- Mats down when wet which can lead to anaerobic conditions
- Not the worms preferred bedding material
- Unknown source of inks
- The finished vermicast might be of a lower quality – this is highly subjective based on way too many factors including determining what quality vermicast is
Peat moss is the decayed material of moss that has decayed over a very long time. This material is typically found cooler regions and swamp/bog habitats. Peat moss is typically used as a soil amendment in potting mixes and garden beds. The material is somewhat acidic and is favored by acid loving plants such as blueberry, azalea, rhododendron, etc. The material has excellent moisture retention and a large surface area. Many worm farmers will ship worms in peat moss to buyers. It is a very versatile material but it does have some controversy surrounding how it is mined. Although peat moss is decaying plant material, the length of time it takes does not necessarily make it considered renewable.
- Excellent moisture retention
- Large surface area
- Can filter out bad smells
- Fairly inexpensive
- The material is considered sterile and doesn’t contain pathogens or unwanted pests
- Can raise the pH of the system – this concern may be overblown but it is possible
- Have to purchase the material
- Not a renewable resource
- Some brands contain additional fertilizers – avoid this
- Can potentially cause protein poisoning in the worms
Wood Stove Pellets
This material is not as common but is an excellent material. The pellets are basically compressed sawdust. The material is used primarily for heat and even as a cat litter alternative. There are a number of brands that don’t have any added fillers or chemicals which is the source one should use. Lowes Home Improvement carries a self branded version that is typically only available during the winter. When water is added to the material it will expand about 2.5x its dry size. So a little can go a long way. The material is great at absorbing moisture and has a large surface area. Since this material is wood based, it will break down slower than cardboard and paper but it can provide habitat for a more fungally dominated compost. This is a good thing! One downside is that when the material is saturated with water it can become quite heavy and the fine particles will stick to your gloves or hands.
- Excellent moisture retention
- The dry material expands roughly 2.5x its size providing lots of material
- Can promote a more fungally dominated finished vermicompost
- Large surface area
- Can filter out bad smells – it does smell like wood which maybe a con for some
- Not a free resource
- Can become quite heavy
- Can limit airflow
- Availability can be an issue outside the winter months
Coconut coir has been used for many products such as doormats, brushes, and rope. The coir is basically the coconut husk that has been stripped or de-fibered. The material has gained popularity as an alternative to peat moss as it is considered a more renewable resource than peat*. Coir has many other agricultural uses such as a medium for mushroom farming, an animal bedding, and used to deter snails in greenhouses. As a bedding material, coir is excellent at absorbing moisture, somewhat light and airy, large surface area, and a good filter.
*There are some issues with coir being considered renewable as coir typically comes from palm oil farms that destroyed the biodiversity of the area to plant large numbers of coconut palm trees.
- Excellent moisture retention
- The dry material expands roughly 3x its size providing lots of material
- Can be used as a material in garden beds so even if not fully broken down it still provides benefits
- Not acidic unlike peat moss
- Readily available at most garden shops and Amazon
- Some brands may contain excess salt which is detrimental to worms – the material can be rinsed to remove the salt
- May contain other foreign materials such as glass and plastic – this is from the manufacturing process
- May contain weed seeds
- Can be expensive – especially during the early garden season when demand is higher
Fall Leaves / Thatch
This category could also contain conifer or pine needles, but those are best used as a mulch. Fall leaves are abundant in many areas and is a free, readily available material during the fall. Leaves that are shredded work the best as the finer particles increase the surface area. Leaves will most likely have some beneficial microbes and fungi that will help with decomposition. One issue with leaves is that they can be difficult to moisten. Some tree species such as Oak and Sycamore have more fibrous leaves and take longer to break down. However, if one shreds the leaves and has a pile sit outdoors for a year or so, the leaves turn into something referred to as leaf mold. This material is similar to peat moss or coconut coir in its moisture retention and texture.
- Readily available in the fall!
- Free – one can also pick up bags of neighbors’ leaves
- A great material for other types of composting
- Great water retention when broken down into leaf mold
- Loaded with beneficial microbes and fungi
- Leaves that have not gone through some sort of breakdown do not absorb moisture well
- May contain unwanted pest such as fungus gnats, aphids, or a plant disease
- May have been sprayed with chemicals
Manures can from various sources and can be quite different based on the producer. There are many variables that would require its own post. The manures that are most suitable for worm composting would be from animals that typically only eat plants. Horse, bovine/cow, goat, sheep, rabbit, and pig manures tend to be well suited. These should also be mixed well with some other material such as straw or hay and left outdoors to break down a bit. Manures can also be considered a food source for worms so it is definitely powerful stuff! I just want to note that this is not a material I use as it is not easily accessible in my location. There are other sites that can provide more complete overview and analysis.
- Excellent habitat material that worms tend to thrive in
- The ideal material is mixed with other bulky bedding material can act as bedding and food
- Depending on one’s location this may be an abundant material
- Loaded with beneficial microbes
- May contain a large source of worms as the material attracts them!
- May contain some residual pharmaceuticals from the animal (antibiotics, etc.)
- May not be easy to obtain or obtain suitable material
Soil from one’s yard provided that no pesticide or herbicides have been sprayed are a possibility, but not as the dominant material. Soil can provide a number of beneficial microbes, fungi, and other organisms that can help break down food scraps quickly and provide some nutrition for the worms. However, the material can be too dense (clay soils) or lacks structure (sandy soils). I personally would NOT recommend using this material as it can introduce unwanted pests or worse something toxic to the worms. With so much variability it is best to avoid this material. If one has experience with vermicompost systems and wants to try it in a small amount, that may be ok but this material should be mixed with other bedding materials.
- Readily available
- May have a large population of beneficial microbes
- May contain unwanted chemicals if treated with pesticides/herbicides
- Can be quite heavy and limit airflow
- May contain pests – including fly larvae, fungus gnats, scuttle fly, etc
Which bedding is the best?
Well…it all depends! As with system types it depends on one’s goals and constraints. If one’s goal is primarily to reduce waste then purchasing any form of bedding doesn’t make sense. However, if one is trying to make a specialty vermicast for a specific plant, then purchasing a material to meet that goal makes sense.
For the average home vermicomposter, the free resources is often the sensible choice. If you could only choose one, then cardboard would be my preference. It is free, the worms really like it, and retains moisture reasonably well. Also, especially for indoor systems, cardboard typically doesn’t have any unwanted pests. Many beginners end the vermicomposting journey due to fruit fly invasions.
My personal preference is to have a mix of different bedding materials. This way can hedge multiple advantages while reducing any cons. For example, using a bulkier material such as cardboard with finer material like coconut coir. This combination will retain moisture better than cardboard alone but will also allow one to use less coir to have it last longer. The mix would also have better airflow than using coconut coir alone and can prevent anaerobic conditions. This mix and match method also introduces a more varied diet for the worms.
This materials above are just some of the possible materials. Worms are incredibly adaptive and can respond to a variety of bedding materials. For beginners, just stick with the simplest and cheapest materials. When one becomes comfortable with trying something new out it is best to start small and observe how the worms react.
Here are some other possible bedding materials to consider:
- Pittmoss (an alternative peat moss made with newsprint)
- Dried grass clippings
- Old cotton clothing – NO synthetics
- Wood chips – has a potential to be a great long term bedding that can be reused many times before breaking down
- Natural cat litters – just no cat poo/urine due to the risk of toxoplasmosis
- Cedar bedding for hamsters, guinea pigs, etc