Worm Composting

Worm composting, also known as vermicomposting, involves the aerobic breakdown and stabilization of wastes via the activity of specialized earthworms, other invertebrates, and microorganisms. The end product - known as worm castings, vermicompost or vermicast - is one of the most highly regarded natural soil amendments, offering incredible plant-growth-promoting benefits even when very small amounts are used.

Worm composting is a great option for those with limited space and fairly small waste streams, and can be an excellent partner strategy for both layered composting and bokashi.

Advantages of the Process:

  1. Faster - Composting worms mix, aerate, and fragment wastes, greatly assisting the microorganisms involved in the breakdown and stablization process.

  2. Flexibility of Scale - Since the worms do much of the "work", vermicomposting systems can be almost any size.

  3. Great Indoor Option - Worm bins are a great option for apartment or condo dwellers (and anyone else) who wants to compost indoors. In many locations this may be one of your only options during winter months.

  4. Excellent Partner Strategy - Vermicomposting can be even more powerful when partnered with other composting methods or integrated directly with plant-growing systems.
The benefits of adding vermicast to your soil

Some Challenges with Worm Composting

  1. Need to Care for Worms - In order to be successful with vermicomposting you need to (bare minimum) meet the needs of the earthworms you are working with.

  2. Needs maintenance - When not set up or maintained properly, worm bins can sometimes end up with pests like fruit flies, or create other challenges. Vermicomposting systems may require a bit more dedication than layered composting or bokashi systems.
Hungry Bin Worm Composter

Overall assessment of the vermicomposting method

Vermicomposting is a great choice for anyone with limited space or needing to compost indoors for other reasons. It can also be scaled to whatever size is required, both indoors and/or outdoors. Vermicomposting is well suited for schools and other educational settings, since there is an entire ecosystem at work and - let's face it - worms are pretty cool! 

Worm Composting FAQs


What is vermicomposting?

Vermicomposting - aka worm composting - is a mesophilic (mid-range temperature) composting process that involves the joint action of specialized earthworms, other invertebrates, and microorganisms. It results in the production of a humus-rich, highly valuable soil amendment known as vermicast, worm castings or vermicompost.

How is vermicomposting different from other types of composting?

The main difference, of course, is the major focus on employing certain earthworms to help with the composting process. These worms greatly assist with fragmentation, mixing, and aerating of the waste materials, and they produce a unique compost that's highly lauded for it's incredible plant growth-promoting (among other) properties. Of course, because there are worms involved, extra care and attention may be needed in comparison to some other methods - although, there are many ways we can greatly help the worms mostly "take care of themselves".

Can I use worms from my garden?

Earthworms from your garden usually aren't going to be well-suited for life in an active composting system, especially not a smaller, indoor worm bin. Composting worms, such as Red Wigglers, are what's known as "epigeic" worms, They tend to live up near - or often above - the soil surface, in rich deposits of organic matter. They are much better adapted for processing these richer materials and they breed much more quickly. They can also handle elevated temperatures and crowding much more easily than your more typical "garden varieties" of worms. Soil worms can still be great allies, very often moving into the lower reaches of outdoor systems and helping to process some of the organic matter.

What are the best worms to use?

Arguably the most versatile, and best overall choice, is the Red Wiggler (Eisenia fetida/andrei). They are considered "the king of the composting worms" for good reason! These worms are very easy to work with, can handle a wide range of temperatures, and will process organic wastes very effectively. Their larger cousin, the European Nightcrawler (Eisenia hortensis), has similar abilities and temperature tolerance - and can be a great choice for anyone looking to raise fishing worms - but they do tend to be more temperamental, particularly when being disturbed frequently. They also prefer a cooler temperature and don't reproduce as quickly (they produce fewer cocoons and hatchlings than red wigglers) and time to maturity is longer. They do dig deeper and could provide improved aeration in larger outdoor systems. European Nightcrawlers are great composters but just not as voracious as red wigglers. The tropical species, African Nightcrawlers (Eudrilus eugeniae) and Blue Worms (Perionyx excavatus) are both prolific breeders and waste processors when provided with their ideal conditions, but they are much more intolerant of cooler temperatures, making them less well-suited for vermicomposting in Canada - at least not in outdoor systems.

How many worms do I need to get started?

There is no set quantity of composting worms you absolutely need in order to start up a vermicomposting system. You can easily get started with some worm-rich material from another worm bin, or really, any number of Red Worms or their cocoons. That said, if you want to hit the ground running with your waste-processing and castings-production efforts, we recommend at least 1/4 or 1/2 lb of worms for a small to medium sized home system - 1 or 2 lb for larger systems.

How fast does a worm population grow?

Like so many things relating to vermicomposting, this will depend on a wide range of different factors, including temperature, moisture/aeration balance, nutrition, overall habitat quality, available space and experience of the system manager. Under ideal conditions (so, not necessarily what you should expect in a home worm bin), Red Worm adults can drop 3 cocoons per week. The cocoons can take about 3 to 5 weeks to hatch, and each of those cocoons release an average of 3 hatchlings. Hatchlings can take about 6 or 7 weeks to reach maturity. If you do the math, it's not difficult to see how a Red Worm population could easily expand MANY times in size within a few short months. That said, the more widely suggested "doubling every 2-4 months" may be a more realistic expectation for most home vermicomposters. Just remember, once your system is starting to get crowded, you will likely need to give the worms more space (eg start up a second bin and put half of the worm-rich material in there) in order to continue seeing population growth.



What is the best worm composting bin?

As is the case with layered composting, and to a lesser-extent bokashi, there is no one correct answer - other than to say that the best bin really depends on YOU and your particular situation and goals. If you really just want to dabble with worm composting and test out the process a bit, some sort of small, very basic DIY tub system may be the way to go. If you want to get a bit more serious, and don't mind spending some money, something like an Urbalive worm farm, Urban Worm Bag or a Hungry Bin can be a great choice. One thing we do recommend when you are just starting out, is to keep things as simple as possible, so as to help ensure your success. Once you master the fundamentals, and witness the magic of the process, you will be in a much better position to expand your efforts and reap the additional rewards from doing so.

Can I put red wigglers in a tumbler?

Technically, yes - composting worms could be added to a tumbler, and in some cases, even do OK. But, our feeling is that, on the whole, these systems are far from ideal for vermicomposting. For starters, they are raised above the ground, often dark in colour, and very commonly sitting in locations that receive a lot of sunlight. In other words, it is highly likely that a tumbler environment will reach temperatures considerably higher than what is "ideal" for composting worms (to stay alive, let alone thrive). Next, it's important to consider the motion - tumblers are designed to be...well, tumbled, regularly. This constant disturbance isn't ideal for helping our wiggling friends do what they do best, since they generally prefer an environment with a lot less disturbance. We do feel tumblers can be potentially helpful for vermicomposting, though, since they can be great for mixing different wastes, and allowing these mixes to get colonized with loads of microbes and start to break down. In other words, this can be a great way to make really top notch worm food mixes - potentially helping to speed up the vermicomposting process.

Can I use a clear bin as a worm bin? For educational purposes?

Although we don't recommend them, clear bins can be ok for vermicomposting if you cover them with a breathable blanket/sheet or something similar. It's important to maintain dark conditions when the systems isn't being observed, since the worms are very sensitive to light. One bonus is that this sort of cover can actually reduce the chances of your system getting invaded by pests (eg fruit flies), but it does make good bin ventilation even more important. We totally understand the appeal of having clear bins in an educational setting, since it can increase the "cool factor" when the kids can really see what's going on in the system. But do keep in mind that, even with a totally clear bin, you still may not end up seeing all that much. Any worms that are close to the walls will just burrow inside and vanish into the bedding to avoid the light once the cover is removed. Also keep in mind that many clear plastic bins use a harder plastic that can crack a lot more easily, so you may find it a bit more challenging to add ventilation holes (which is very important). Bottom-line, our overall recommendation would be to avoid clear bins, since the negatives will tend to outweigh the potential benefits.

How do I set up my worm bin?

Each particular worm bin (and vermicomposting system in general) has its own unque set of set up steps for best results - but there are still some core principles and guidelines we recommend sticking with no matter what system you are using. Our initial goal as vermicomposters should always be to create a safe habitat for our worms. This should consist mostly of damp bedding materials, ideally combined with some form of safe living material, and a small amount of food to get the worms started. In most systems (other than ones with smaller, shallow trays) it is helpful to think in terms of 3 key zones:

  1. Bottom bedding zone - sometimes referred as  a ""false bottom"",
  2. Worm zone - middle zone where damp bedding and living materials are combined with a small amount of food, and worms are added, and 
  3. Cover bedding zone - thick layer of bedding at the very top of your system.

The worms need bedding materials that offer both air flow and water absorption capacity. The materials in the bin should be moist/damp but not overly wet.

Try to aim for a ratio of around 70% bedding to 30% food in your bin!

Suitable bedding materials may include a combination of at least 3-4 of the following materials:

  • shredded leaves,
  • shredded cardboard (avoid shredded paper),
  • coconut coir,
  • hemp,
  • aged horse or cow manure,
  • woodchips (for larger systems),
  • straw and/or hay,
  • smaller amounts of compost (ideally worm castings from another system),
  • organic potting soil or loamy garden soil.

You can either mix your selection of materials together initially or layer in the different materials. When using coco coir with other materials, it’s beneficial to mix the materials.

Remember that the worms will eventually consume their bedding, so it’s important to add more regularly!

The example here shows bedding layers in a non stackable style worm bin with easy to access materials.

Bedding Materials for your worm bin
Can I keep my worm bin outdoors?

For best results, most small to medium-sized worm bins should be kept indoors since climate control greatly assists with the effectiveness and consistency of your vermicomposting process. Still, it is perfectly fine to keep bins outside during certain times of year. Just keep in mind that smaller bins (especially anything made of plastic) should be kept out of direct sunlight, ideally in a location protected from precipitation. Also note that the vermicomposting process can slow down significantly when temps drop down below 15 Celsius, and worm bins should never be left outside for very long once temps start to go below the freezing mark.

Can I keep my worms alive outdoors in the winter?

The good news is that Red Worms (and European Nightcrawlers) are surprisingly cold tolerant, and can survive essentially until they freeze solid. We've literally found Reds wiggling away in frozen chunks of compost during the winter, so even some of the habitat materials can start to freeze before the worms themselves. Low-lying systems - ideally with an in-ground zone - bulked up with lots of bedding materials like straw and hay (the latter which can provide even more food value) can be very effective in regions that experience even moderate to serious winter weather, especially regions that receive a lot of snow, since it can provide excellent insulation as well. One thing we absolutely DON'T recommend is keeping most above-ground worm bins sitting outdoors during the winter in regions that experience extended periods of below-freezing temperatures. And of course, it's also important to mention the obvious fact that the absolute best winter system is an indoor system! ;-)

How well will Red Wigglers survive Northern climates?

There are a number of factors that can determine your chances of success with vermicomposting in cold regions. The fact that you have worms in your garden is a good sign (but it is very unlikely they are Red Worms). This indicates that it should be possible to keep composting worms alive outdoors, with the right sort of set up. Of course, the easiest way to keep composting worms going in northern climates is by using indoor vermicomposting systems. One of the great advantages of worm composting is the fact that you can easily compost indoors all year long, avoiding a wide range of climatic challenges. Assuming you prefer to keep your systems outdoors, there are a number of effective ways to do so. It's important to note, though, that actually keeping a fully active system going all winter is considerably more challenging than just keeping your worms alive in colder regions. Your best choice will likely be some form of low lying, ideally in-ground, system with large amounts of insulating materials like straw and fall leaves. Above ground systems are far more likely to freeze solid during the winter. The beauty of composting with worms is that there are so many options. If you would like more specific details on your region in particular, we would be happy to help.



Do I need to turn my worm composting system?

The short answer is no. You definitely don't need to turn a vermicomposting system the same way you do with a larger thermophilic composting system. Remember, the worms themselves do a great job of mixing and aerating all those materials you've added. It is however important to fluff up the habitat periodically with your hands or a hand rake - especially as a system matures and a lot more vermicompost accumulates - since this helps to provide important oxygenation, which improves the overall efficiency of the process.

Why does my worm bin stink?

There are a variety of factors (and combinations of factors) that can lead to stinky worm bins, but the two main factors relate to anaerobic (no oxygen) conditions and the type of waste materials (and amounts) you are adding. It is very common for a typical home worm bin to smell bad when too much food has been added at once and/or swampy conditions have been allowed to develop. Freely draining systems can help with the second issue, but it is still very important to balance out foods with bulky, absorbent bedding materials. Making sure your system has excellent aeration can also really help. One additional strategy to consider is the use of "living materials" and/or BioChar, both of which tend to have excellent odour trapping abilities. Circling back to food materials, not only are large deposits of food often the culprit, but the types of food being added can also play a role. For example, cruciferous vegetables such as cauliflower and cabbage has sulfur compounds in them that can give off foul odours as they break down. Sugary, water-rich wastes (especially when deposited in concentrated amounts) tend to ferment quite readily, which can not only produce strong odours, it can greatly increase your chances of attracting fruit flies and other pests.

I have mold growing in my bin - is that ok?

Fungal growth in your worm composting system isn't necessarily a "bad" thing, but it may be an indication that the system isn't being managed properly. Generally, white fluffy mycelial growth, or even actual mushrooms popping up isn't a problem - and your worms will likely even benefit by munching on it - but if you see a lot, especially anything that looks like mold (and you actually see clouds of spores released), it probably means that too much food has been added or that they've been left too exposed. Certain wastes like bread can be more prone to mold growth. It is best to always make sure you have lots of cover bedding to bury your wastes under. Various forms of food optimization, such as chopping and mixing can also help. Speaking of mixing, if you do see a fair bit of growth happening, one helpful strategy you can use before toping the system up with more bedding, is simply to mix things up gently with your hands or a hand fork. This helps to break up mycelium and bury the exposed fungal growth, making it more likely that worms and other creatures will feed on it.

Can I end up with too many worms in a worm bin?

As prolific as these worms are in the breeding department, the good news is that you are very unlikely to end up with a worm bin literally overflowing with worms. A Red Worm population tends to self-regulate once densities of worms reach a certain level. Breeding will slow down, and while cocoons will still get dropped, the hatching rates will likely being considerably lower than when a population is much smaller. A great option for systems that do seem to have very high densities of worms - if you have the space, and desire to expand your efforts - is to remove half of the contents and start up a new system with it (additional bedding, and likely some food should be added to each of the "new" systems as well). This is what's known as bin "splitting", and it can be a great way to continue expanding your vermicomposting efforts over time. For those who don't wish to expand their worm herd, periodically donating worm-rich material to others wanting to give vermicomposting a try can be a great way to help "spread the worm".

Do I need a worm sitter if I go away on holidays?

In most cases you really shouldn't need anyone to watch over your vermicomposting systems when you go on vacation. In bins where you've added a lot of bedding materials (something we highly recommend), especially paper-based bedding like shredded cardboard, worms can be sustained for many weeks on end - even months in some cases - without any additional food deposits. Three common reasons for worm populations dying/disappearing when people go away include: 1) adding huge food deposits right before leaving - which can cause overheating and other problems, 2) leaving the system in an unprotected outdoor location where it gets too hot, and 3) using a type of system that dries out too quickly (again, often in an outdoor location). Bottom-line, to ensure your greatest chance of success, top your system up with lots of damp bedding (eg shredded cardboard), and either make sure it is in a well-protected (out of direct sunlight) outdoor location or, even better, in a climate-controlled location, before you head off on your next trip.

How do I stop my worms from climbing up the sides and lid?

Some roaming in an enclosed worm bin, especially plastic systems with less ventilation, is totally normal and not necessarily something you need to worry about. Nevertheless, a great strategy that also helps in multiple other ways is to simply maintain a nice thick layer of absorbent bedding materials (shredded cardboard/paper can be excellent for this) up top in the system. This tends to keep this upper zone somewhat drier, and the worms tend to stay down more. Use of some form of worm blanket directly over the worm zone can also help. If your worms still seem really restless or they are actually trying to escape, please refer to the next answer.

Why are my worms trying to escape?

There are a variety of reasons for worms wanting to leave a worm bin or outdoor composting system. For starters, certain types of worms are just naturally more restless and temperamental than others. Blue Worms (Perionyx sp), for example, are very much a roaming worm by nature - especially during rainy or very humid conditions. There are reports of people finding them up in trees, and even on top of tall buildings in the regions they are native to (where there is high seasonal rainfall). If other composting species, such as our trusty Red Worms, seem extremely restless or are obviously trying to escape en masse it is likely there is some form of hazard in your system. Noxious gases, such as ammonia, can be a culprit, especially in systems with less ventilation. Adding foods with excessive levels of salt or other harmful chemicals can also cause major issues. Overheating, especially in larger systems, is another possible reason your worms want to escape. NOTE: shortly after adding worms (that have been shipped) to a new system, it's not uncommon for them to exhibit some restlessness. Remember to add a nice thick layer of bedding up top - but you may even want to leave the lid off/open and shine a light over top just to ensure excellent air flow, and discourage them from venturing up.



What is the best food for my worms?

Fruit and veggie wastes tend to be the best worm food choice for the average home vermicomposter. But they are not all created equal. Some take much longer to break down than others, so you may find that certain foods (eg cabbage, carrots, potatoes) take a fair bit longer than others (such as leafy greens, melon etc). With water rich foods like these it is important to make sure you are balancing them out with dry absorbent bedding materials, especially if your system doesn't drain freely. Other good foods can include coffee grounds (in moderation) and tea bags. Outdoors, aged, bedded livestock manures can be a fantastic food for your larger, well ventilated systems. For more info about worm foods and feeding, be sure to check out our worm feeding page!

Can I add pet wastes to my worm bin?

We don't recommend adding dog or cat feces to any sort of typical home worm bin - even one you are dedicating to pet waste vermicomposting. Not only are these materials unpleasant to work with (eg have very bad odours), but they can also be hazardous to humans in not handled/managed properly. Wastes from herbivorous pets such as rabbits, guinea pigs or gerbils should be just fine in moderation when using small to medium sized worm bins - and can be excellent materials to add freely to larger outdoor systems. Speaking of larger outdoor systems - a larger, layered system with excellent ventilation and management can actually be an excellent way to convert dog and cat wastes to rich compost, especially when composting worms are added to assist the process. These should be systems dedicated to receiving these wasts (ie don't add them to your regular systems), and the compost should be used solely for ornamentals, shrubs and trees, not food producing plants.

What types of food should I avoid?

For a typical small-to-medium sized home vermicomposting system ("worm bin") you should always avoid the usual composting "no no" materials, including meat, dairy, excessively salty foods, and dog/cat feces. We also suggest you don't add material straight from a bokashi bin into a regular worm bin. For other foods, it can be more a matter of simply adding in moderation. Citrus and other really acidic foods (eg pineaapple), foods with potential volatile oils - such as onions and hot peppers - and starchy wastes, epecial the ones that are rich in protein, such as various legumes. Larger, established systems will tend to be more forgiving, so you will likely be just fine adding larger quantities of challenging wastes to these systems - epecially if located outdoors. As we've touched on elsewhere, pet wastes can be great for composting (especially worm composting) when you dedicate an outdoor, well ventilated system to the task, and only use the finished compost for non-food plants. For more info about worm foods and feeding, be sure to check out our worm feeding page!

Can I add citrus to my worm bin?

As touched on in the previous answer, citrus is OK for a worm composting system, but it should always be added in moderation. The peels contain potent volatile oils that can fend off microbial attack and potentially harm the worms, and the fruits themselves are highly acidic which can also create issues if too much is used at once. Generally, larger outdoor systems should be able to handle a lot more of these types of materials, but we still always recommend using as diverse a mix of food and habitat materials as you can. For more info about worm foods and feeding, be sure to check out our worm feeding page!

Can I add farm manure to my worm bin?

Manure can be a tricky material to work with, but it also happens to be one of the best wastes to add to a vermicomposting system. Firstly, it's important to realize that the word itself refers to wide range of animal wastes and products - so, don't ever assume that just because something is called ""manure"" that it's good for your systems. The manures we mainly recommend for vermicomposting are those of herbivorous livestock, including: horse, cow, goat, sheep, and rabbit manures - but there are certainly others (llama, alpaca etc) that can also work really well. Aged, bedded horse manure has been a favourite among many vermicomposters and worm farmers (ourselves included) over the years, since it offers excellent habitat value, along with good nutrition. Rabbit, sheep and goat manures are rich in the essential nutrients needed to support the rapid growth and reproduction of the worms, and the small, uniform pellets provide more surface area for microbial activity and ultimately, easy decomposition.

If you are wondering about pig manure, the good news is that - according to world-renowned researcher, Dr. Clive Edwards (who sadly passed away in 2021), this is one of the absolute best vermicomposting materials, both in terms of worm nutrition as well as the quality of the castings produced. Our caveat is that this can be a challenging manure to work with, especially for the average vermicomposter, since it tends to be very wet, and smells much more strongly than most of the other great choices we mentioned.

It's important to keep in mind that even in the case of the ""best"" manure choices, fresher materials are often going to be higher in salts, and have a much greater potential release ammonia gas - both of which are very dangerous for your worms. In most cases, unless you are experienced with vermicomposting manures, we'd recommend you avoid adding them to any of your small to medium sized home worm bins (especially the smaller, enclosed plastic bins). You are much better offer adding fresher manures to larger, well-established (and well ventilated) outdoor systems. Well-aged and pre-composted manures will usually be the best choice - especially for smaller home systems. These will tend to be darker in colour, and have a much more earthy smell to them (not a strong manure odour)

What types of paper and cardboard can I use as bedding? Which ones should I avoid?

The best choice will always be bedding materials that don't contain harmful chemicals, dyes, inks etc. In the case of paper products, brown kraft paper and cardboard is likely as good as it gets. Environmental standards for printed inks tend to be a lot higher these days, so you are likely ok to use newsprint and other paper/cardboard with printing on it - black and white ink likely being more favourable than colour. The one type of paper/cardboard we don't recommend using is anything with glossy, colour printing, such as magazines and a lot of flyers, since these can contain heavy metals and other chemicals we don't want in our systems. Various types of bleached paper should be ok in moderation, but we would never recommend using it as your main bedding material.

Apart from the potential chemical concerns, another issue with shredded paper (vs shredded cardboard, for example) is that it tends to mat down once wet, often impeding air flow, potentially creating anaerobic pockets. One great strategy we recommend for paper (ideally, brown kraft paper as much as possible) is ""scrunching"". The idea being that you just turn bigger pieces of paper into ""scrunched"" balls and mini logs (by hand) that will tend to support air flow much better than shredded paper.

Can I put weeds and other yard wastes into my worm bin?

These types of wastes can be used on moderation in a typical worm bin, especially if chopped up well and combined with other wastes and bedding materials - but they tend to be better suited for your outdoor layered (or hybrid) systems. Some tough, resistant materials can take a long time to break down, and various green wastes like weeds and grass, can release ammonia gas as they decompose, which can be very toxic for your worms (NOTE: the same can be true of fresher farmyard manures so be cautious with those as well).

Are there any particular weeds that should not go in a worm bin? I have wild foxglove and horsetail growing in my yard.

Vermicomposting is a mesophilic (mid-range) composting process. As such weed seeds are not necessarily killed in a worm bin, although most microbial pathogens are. There are certain plants like rhubarb, foxglove, lupins and others that require hot composting as their leaves are poisonous and the toxic oxalic acid in them can only break down in high heat, in the case of horsetails they require above 40 degrees which can't be done in a worm bin. Instead we would put them in layered composting bins outside to process. Two other types of plants we would advise against putting in a worm bin are poison ivy and Jimson weed. As for diseased plants, they require temperatures over 65 degrees to kill most plant disease pathogens. Those aren't temperatures that can be reached in most home composts so it's better to bury those plants or have them taken away. If you are going to add certain weeds to your bin, make sure that they are not toxic or diseased plants and we would suggest moistening them, chopping them up, mixing them with carbon-rich materials like leaves/shredded cardboard, etc.. and let them rot a little bit to have them break down faster. Otherwise, it can take a few months for some weeds to break down.

Should I freeze food waste prior to adding it to the worm bin?

This is a great question, and a topic that can lead to debate among vermicomposters. We like to view things from a balanced perspective. On the one hand, freezing usually requires power consumption (the exception being when you can put your scraps outdoors during sub-zero weather), so it could be argued that it's not very environmentally-friendly. On the other hand, freezing can be an excellent way to start the breakdown process, killing plant tissues and rupturing cells, making it much easier for microorganisms to invade and initiate the decomposition process. Another great advantage of freezing is that it kills any fruit fly eggs or larvae that may have been in the wastes. In terms of optimization, if freezing/thawing is combined with chopping and mixing with other materials (especially if you include living materials) you can end up with some amazing food blends. It is especially helpful for materials that resist breakdown - that can even start growing in compost heaps when added fresh - such as carrots, celery, beets, potatoes, turnip and cabbage. Lastly, one other small benefit is that frozen wastes can help to lower temperatures in vermicomposting systems that are getting too hot. A very important caveat, however, is that if you add too much frozen food, it can actually have the opposite effect - actually increasing heating, due to microbial activity - once the wastes have thawed out. Bottom-line, freezing foods definitely isn't mandatory for successful vermicomposting, but it is a helpful strategy (that likely doesn't consume very much electricity) you may want to consider.

How do I give worms eggshells and how often?

Eggshells are a great source of slow release calcium to help maintain the optimal pH level in your worm bin and helps with worm reproduction. The grit also aids in worm digestion!

To prepare egg shells for your worm bin, follow these steps:

  1. RINSE the eggshells: After using the eggs, rinse any remaining egg residue off the shells with cold water.
  2. DRY the eggshells: You can either dry them out in the sun, laying them out in a single layer on a wire mesh/screen to allow for good air flow or you can put them in an old egg carton. You can also place them on a baking sheet in an oven set at 300 degrees for at least 5 minutes.
  3. CRUSH the eggshells: Once the eggshells are completely dry, crush them into small pieces. You can use a mortar and pestle, rolling pin, or put them in a plastic bag and crush them with your hands. You can also grind them up in a blender or grinder. The pieces should be no larger than 1/4 inch in size, ideally they should be ground up to a powder.
  4. ADD the crushed/powdered eggshells to the worm bin: Mix the crushed eggshells gently into the worm bin, you can do this at feeding time.

We recommend adding up to 1/2 cup of eggshells to your bin during a one month period for small to mid-sized worm bins.

Remember not to add excessive amounts of eggshells at once; moderation is key to maintaining a balanced environment for your worms.

See: Adding Eggshells to Your Worm Bin

Can I add compostable plastics to my worm bin?

Most compostable plastics are designed for breakdown in a large-scale, thermophilic composting system, not the mesophilic environment found in a typical vermicomposting system. These biodegradable plastics should eventually break down, but they will likely be a hassle with deal with until they do. As such, we don't recommend adding any bio-plastics to your home composting systems.

How much should I feed my worms every day?

The best way to feed your composting worms is based on how quickly they are consuming what is being added to the system (and this can depend on a wide range of factors) - NOT based on specific amounts per day, week etc. A good rule of thumb for most home systems, though, is to feed, at most, 1-2 times per week. This greatly reduces the risk of overfeeding, and also helps to ensure the worms aren't being disturbed too much. Some people recommend an approach known as "pocket feeding", where you bury small food deposits in different parts of your bin over time (ideally staggering deposits by at least 2 or 3 days, if not longer). A much simpler (and potentially even more effective) strategy we recommend involves simply adding in thin layers of food at the top, and then convering with a thick layer of bedding. Be sure to check out our worm feeding page for more info about this important topic!

Is it possible to overfeed a worm bin? 

Absolutely. It's important to remember that even hardy composting worms usually can't just live in 100% "greens" (N rich composting materials) - they need a balanced habitat. Overfeeding is especially common in smaller, enclosed plastic worm bins, which tend to be far less forgiving. If you have a lot of waste materials available regularly, we suggest you set up at least one larger layered (or even better, layered + worms) system outdoors so you can handle all your wastes effectively. It is much less likely you will "overfeed" in a larger outdoor system with excellent ventilation, especially if you have things nicely balanced with bedding and living materials - but do keep in mind excessive deposits in outdoor systems can attract animals, especially if it's not covered by carbon rich materials.





Will my worm bin attract pests?

Firstly, it's important to remember that a diversity ecosystem of different organisms is actually really important for the vermicomposting process, so a good place to start is to develop a solid respect for many (if not all) of the critters you see running around in your bins. It's also important to note that outdoor systems are going to be far more likely to attract a larger range of organisms, so apart from animals that can legitimately disrupt the activities of the worms, or even harm them, it's better to focus more on taking the best care of your worms, than on battling various organisms you don't want to see in your systems. This last point is really the key in general when it comes to "pest" prevention, since when you cater to the needs of your worms effectively, they will tend to thrive and other organisms won't cause any issues whatsoever. Always remember your bin management best practices: 1) feed in moderation, based solely on how quickly the worms are processing wastes, 2) bury food deposits in plenty of bedding (and potentially living materials), and 3) make sure your system has good ventilation, and potentially even drainage to help prevent foul odours from developing.

How do I stop ants from getting into my worm bins

Ants will typically only be an issue in outdoor vermicomposting systems, and you should be able to at least discourage them from actually building a nest simply by catering to the needs of your composting worms as best you can. Ants tend to like pretty dry conditions, while worms of course like it pretty wet - so always make sure to keep your system as moist as possible, while still really well-oxygenated. Ants also love a lot of typical kitchen scraps, so remember to feed in moderation and also to use those various bin management best practices such as burying food deposits under bedding and living materials. With smaller bins sitting outdoors, you might try sitting the bins in a tray of water (assuming no surfaces with ventilation or drainage holes are submerged), since the ants will not want to swim out to the bin just for a meal.

How do I deal with fruit flies?

Prevention is always the best way to avoid hassles with fruit flies. We recommend keeping your bin(s) in a location away from potential sources of these pests, such as kitchens where fruit are sitting out. Just generally, stay on the look out for any signs that fruit flies are present in your house - and if spotted, take steps get rid of them (and the source) as quickly as you can. Simple traps using small containers with some apple cider vinegar (or something like kombucha) and a drop of dish detergent can be surprisingly effective for trapping adults. As funny as it might sound, regularly vacuuming flying adults (especially in cases where you end up with a lot) can really impede the populations overall breeding potential. Always ensure your food deposits are buried under thick layers of carbon-rich bedding materials (living material can really help as well) to reduce the chances of attracting them. Hemp or coir worm blankets can help with this as well. Keep in mind that certain fruit wastes, such as banana peels can actually already have fruit fly eggs in them - so you may want to freeze fruit peels before adding them. NOTE: with outdoors there is very little you can do to completely prevent fruit flies from invading, but system management best practices are still beneficial.

How do I deal with fungus gnats?

As is the case with fruit flies, avoiding gnats in the first place is obviously much better than dealing with an established population. It's important to note that various types of gnats, including fungus gnats, can actually be a bit trickier to avoid since it is more than just rich fruit/vaggie wastes that can attract and sustain them. The good news, at least, is that in a lot of cases you won't end up with nearly the same level of infestation as you see with fruit flies, and the adults also tend not to be quite as much "in your face". In terms of dealing with established gnats, various types of yellow sticky traps can help you catch a lot of adults, as can the tried and true "vacuum method" (mentioned in the fruit fly response). With really well-developed populations, one of the most effective strategies is the use of parasitic nematodes, especially Steinernema feltiae.

What are the little white things in my worm bin?

There are a number of different possibilities fitting the description of "little white things" that can be found in worm composting systems. One of the most common would be springtails, which - if you look really closely - should have an elongated body with legs and antennae. What's interesting is that these common composting varieties don't seem to have the spring appendage (fercula) that gives these critters their name. If your white organisms happen to be round, very slow moving and somewhat shiny, you're likely looking at a common type of mite that appear in worm bins - especially when there is a lot of food, excessively moist conditions, and less air flow. If your creatures are somewhat worm-like, but quite short and stubby, you may have fly larvae in your system. And lastly, if they are worm-like, but very thin and elongated, they are probably pot worms. None of the organisms mentioned are, themselves, "bad" (i.e. they won't cause problems, harm the worms etc), but they may, in certain cases, be an indication of some less-than-ideal conditions that have developed (overfeeding can be a common culprit).

What organisms will eat my worms?

The good news is that there aren't really too many organisms that will put any sort of serious dent in your composting worm population. Sadly, the creatures that have killed the most worms by far are humans (i.e. worm bin owners). Still, it's worth mentioning some organisms that are known to feed on worms, so you can keep your eyes peeled for them and, in certain cases, take steps to help remedy the situation. Various types of beetles - including Rove Beetles, which can be very common in composting systems - can munch on (usually smaller) worms, but it is rare to notice any sort of real impact, and they can often be very beneficial for keep other small organisms (eg springtails) in check as well. Centipedes are another voracious predator - and likely one that is a lot less welcome than even predatory beetles - that can be common in outdoor systems. The only type you might see in any sort of real abundance is the soil centipede, which is a much smaller, thinner-bodied variety. Moving up in size, both moles and shrews can be voraceous worm predators in outdoor systems that are in contact with (or at least in close proximity to) the ground. If you know either of these are in your area, you may want to take additional steps to protect outdoor systems (eg. use completely enclosed, but well vetilated bins these animals can't get into). Various birds, such as American Robins, are very talented worm hunters, and may put a dent in your populations if you are using windrows or other open beds.

What does it mean if I have maggots in my system?

There are a few key types of maggot to watch out for in a vermicomposting system. The first two are smaller, white maggots that can range from a few millimetres to about 1 cm in length. These are the maggots of various "house flies" and stable flies. House flies are generally attracted to richer wastes, often with foul odours - so seeing a lot of house fly maggots often indicates that too much food and/or the wrong kinds of food (eg meat) have been added or that the system is being otherwise poorly managed. Stable flies look almost exactly the same as house flies, and their larvae are very similar in appearance as well. As the name might suggest, they are very common on farms, where they thrive in rich manure deposits. So, if you are seeing a lot of maggots in a system where you have added lots of fresher manure, this is likely the type of maggot you're looking at. As a side note, and word of warning, the one big different between stable flies and house flies is that the former will happily bite humans and other animals (only the adult flies, not the maggots, thankfully). The last important maggot to mention is the larvae of the black soldier fly. You won't likely find these in most parts of Canada, but they may be spotted in the southern reaches of BC and Ontario. These are much larger maggots, both in terms of length and width, and they are very impressive waste-processors in their own right. If you are finding an abundance of them in a system, it's not necessarily a problem, but it may indicate that you have added too much food at once and that conditions may not be favourable for your worms (the maggots are much more tolerant of high temperatures, ammonia gas and other hazards that can kill your worms). A great strategy for discouraging flies from laying eggs, and even for improving a system where you are seeing lots of maggots, is to mix in a lot more carbon-rich bedding materials, and maybe even add some form of worm blanket. These strategies improve the air flow and help to reduce the overall richness of the system, making it less attractive to flies.




How long does it take for worms to make compost?

Once they are settled in, composting worms will start producing vermicast right away. How long it will take for your system to be ready for its first harvest will depend on a variety of factors, though. The type of system being used, average temperature, moisture content, aeration, experience/skill of the person managing everything - among other factors - will all play an important role. While you may need to wait 2-4 months for your first major harvest, we actually encourage everyone to periodically remove smaller amounts (and test it out!) as soon as you start to see it accumulating in the system(s). A great time to do this is any time you feed, and you should use it as an opportunity to add new bedding materials as well.

How do I separate my worms from the compost?

This will depend on the type of system being used. With a fairly basic tub system, some form of "dump and sort" approach is likely your best bet. If you empty the contents out into a large tray or shallow tub, you can get the worms to continue moving downwards using a combination of gentle disturbance (roughing up the surface with your hands or a hand fork and slowly removing material - maybe even blowing air across the surface) and a source of bright light above. Eventually, you should be left with a heap of mostly-compost, and a heap of mostly-worms. NOTE: It is ideal to already have one or more new systems set up and ready to receive your worms. With continuous-flow systems, the process itself tends to help you separate the worms, since they should (in theory) continue moving away from zones rich in their wastes, towards zones rich in food materials. Of course, things don't always work out this nicely, and you may need to do some additional separation, using an approach similar to what was described above.

How much compost can I harvest from my worm bin?

This depends on a variety of factors, including the type of system you are using, how far along the vermicomposting process is in that particular system, and how recently you harvested from the system. If you are using a stacking worm bin (eg Urbalive), once you see that the majority of the worms have migrated to the second tray you should be ok to harvest the entire contents of the bottom tray. With some form of basic tub system, you have the option of A) being really patient, and letting everything chug along for at least 2-6 months before performing a whole-system harvest, or B) - as we often recommend - you can actually start taking out smaller amounts of castings at the same time you are adding food deposits, once you start seeing accumulations. Just remember to top up the bedding when you have removed castings from the system. The second option is of course more fun, since you can start putting those rich castings to use a lot sooner (in a matter of weeks, rather than months)! With a single-compartment flow-through type of system, such as the Urban Worm Bag or Hungry Bin, once the "priming period" - the stretch of time when you are waiting for enough castings to accumulate in the lower half of the system - is finished, you should be able to start removing castings from the bottom on much more of an ongoing basis. We recommend erring on the side of caution when it comes to amounts, since you definitely don't want to harvest so much that the main worm habitat zone starts falling out of the bottom. The good news is that even a small amount of castings goes a long way! :-)

Can I just dump the entire contents of my worm bin in the garden? (Will the worms be OK?)

In most cases we would encourage people to take the time to separate the worms from the compost before adding it to their garden. For starters, composting worms are not actually adapted for garden soil, but rather for an environment with much higher concentrations of rich organic matter. They may do ok for a period of time - especially if you happen to have rich, organic soil - but eventually they will likely migrate away or perish. It's also important to remember that if you dump your worms, you'll either need to buy more for your worm bin, or you may not be able to continue turning your food scraps into rich castings! ;-)

The good news is that separating worms from the compost is relatively easy with a basic light harvesting method. Ideally, you should dump out the contents of your bin into a large, shallow tray (something like a black mortar mixing tray can work very well) sitting in a brightly lit location. Start by gently breaking up the worm-rich material with your hands or a small garden fork. Spreading it out as much as you can will expose more surface area and help to dry everything out. If it is particularly wet (eg. when using a tub system with no drainage), you may actually want to place some dry cardboard, or another absorbent bedding material down in the bottom of the tray before dumping in the contents of your bin. One other helpful strategy can be to set up a fan next to the tray so you can blow air over the surface of the material. Not only will this help to dry it out, but it will also help encourage the worms to keep diving down.

At this point it becomes a process of letting the upper layers of compost dry and then gently scraping them off. ""Roughing up"" the surface (gently) with your hands or a hand fork between scraping sessions can help a great deal (and also tends to send the worms further down). This process can take a bit of time - we recommend leaving your tray to sit while you do other things, in between scraping sessions. But in some cases - eg working on a series of trays outdoors on a nice sunny day - you'll be amazed by just how much compost you can harvest in a relatively short period. Get started with the first tray, work your way down the line - and by the time you get to the last one, your first tray may be ready again.

Once you get down towards the bottom of your tray(s), you'll start to find more and more worms, and at some point you should just transfer the remaining contents over to a new system (great idea to have something ready to go before you harvest).

How is worm compost different from other types of compost?

Worm compost (also known as vermicast, worm castings and vermicompost) has been shown via academic research to have some unique properties that help to explain why it is so highly-valued by gardeners and farmers, especially those who have put it to use already. This type of compost has been found to contain a variety of plant growth promotors and regulators, such as auxin and various humic acids, helping to explain why the material (if high quality) is able to boost plant growth significantly, even when the full nutritional needs of the plant are already being met with traditional fertilizers. One of the other amazing things about vermicast - unlike most composts - is that relatively small quantities can have a very significant impact on the growth and overall health of plants.

How do I store finished worm castings?

If you don't have plans to use your newly harvested worm castings right away (eg. during winter months), there are some fairly easy storage solutions available. Likely the best option involves putting your castings in a container similar to a basic worm bin. Something like a Rubbermaid Roughneck tote or other plastic tub, with some air holes in the lid should be fine. You won't need (or want) as much air flow as a regular worm bin, since finished castings won't need nearly the same amount of oxygen as an active vermicomposting system. Aside from that, too much aeration can dry out your castings, which is not ideal. We recommend storing your tub of castings in a location with moderate temperatures, that's out of direct sunlight. A basement or cool-ish location should work well. If you still have some straggler worms, or don't like the idea of losing all the leftover cocoons, you might try adding some tempting food materials (eg some melon or aged horse manure) on top of the castings. This can help stimulate hatching, and then draw the worms and hatchlings up to the top, where they can easily be collected (and then moved to another system). For those who are looking for a simpler, less expensive castings storage solution than a plastic tub, breathable bags (eg polyweave sand bags) can work as well - but castings will likely dry out much more quickly, so it will be important to regularly monitor moisture levels. Adding moistened newsprint or kraft paper on top of the castings will also slow the drying process and will help retain proper moisture levels for a longer period. With larger outdoor systems, castings storage can often just happen in the system itself, until such time as you are ready to put the material to good use. If you do decide to harvest from one of your larger systems, we recommend heaping up your castings in a sheltered location, out of direct sunlight and protected from precipitation. A tarp can serve as a somewhat breathable cover that can block most rain and snow, but again, do make sure your heap is out of direct sunlight (at least during summer months) to help avoid overheating, which can have a negative impact on the microbial community in the material.




Why are worms so expensive?

We understand how composting worms can, on first glance, seem really expensive - but it's important to consider all the time, effort, and expense involved in raising healthy worms and getting them safely into the hands of our customers. Raising, harvesting, and packaging worms is a lot more labour-intensive that many people realize. Our Red Wigglers, for example, are raised in specialized systems, housed in a climate-controlled facility, where they receive regular feedings with a wide range of wastes as well as various nutritional and microbial supplements, watering and other ongoing care and attention. Once they are ready to go, even more time is invested in harvesting and packing up the worms (with love) in our unique breathable bags and then either taking additional steps to prep the worms for shipping, or taking the time to meet with our awesome customers, so we can pass along their worms and answer any questions they have. And this doesn't even factor in all the time that's invested in providing excellent education (via the website, social media etc) and ongoing support. We always encourage people to view composting worms as a valuable investment, since your population of wigglers can expand quite substantially - and relatively quickly - when you care for them property!

Can I put red wigglers in the garden?

As tempting as it can be to add Red Wigglers to a soil environment, it's important to remember these are composting worms, which are adapted for a very different habitat than your typical garden worms. As such, we highly recommend either adding them to a more typical worm composting system - or setting up some form of integrated system, to help them thrive right in your garden.

Red Wigglers require a lot of rich, organic matter to truly thrive - something that most gardens unfortunately can't supply. If the worms can't find the food and the conditions they need, they will either migrate to a different location or will eventually die. In other words, for most people who attempt this, it can end up being the equivalent of just throwing their money away (we don't want this, and we know you certainly don't either)! It's important to note that, apart from the insufficient amounts of rich, organic matter, the environment in a garden environment - especially a raised bed - can also end up getting too dry for the worms.

Circling back to the topic of integrated systems, simple vermicomposting trenches or ""worm towers"" (basically just a buried tube or bucket with holes, set up like a typical worm bin) can provide the worms with a rich feeding zone and serve as a sort of home base for the them. Not only will they end up roaming out into the soil, depositing rich castings and providing a bit of aeration the plants can benefit from, but the plants will also likely send roots into the integrated system itself, where plenty of nutrition will be found as the worms process the wastes that get added.

NOTE: With regular deposits of water-rich fruit and veggie scraps, these integrated systems - especially something like an enclosed bucket system - should stay relatively moist for the worms, but it's still a good idea to get into the habit of regularly watering as well (just make sure there is good drainage when using a fully-enclosed bucket or bin).

Are composting worms invasive and harmful in natural environments?

This is an excellent question, and something a lot of people wonder about (or assume is the case). In recent years there has been a lot of coverage of the "invasive earthworms" issue by many popular media outlets. Unfortunately, composting worms have often ended up lumped together with all other earthworms, and viewed as a threat to natural ecosystems as a result. If you look at academic research in this field, however, there is little evidence to suggest these types of worms are creating any real problems. To be clear, yes various composting worms - such as Red Wigglers - are often not likely to SURVIVE in a natural ecosystem (eg in a forest), and in order to truly THRIVE in - let alone take over - any sort of environment there would need to be a lot of very rich organic matter present. This helps to explain why composting species aren't found in great abundance in nature - but rather tend to be closely linked to human habitation and agricultural activities. Composting systems and outdoor deposits of rich wastes, like livestock manure, are the types of environments these worms are adapted for. It is important to note, however, that there are other earthworms - often drawn to outdoor composting systems as well - that are having a negative impact on natural (especially forest) ecosystems. Prime examples include the Asian jumping worms (Amynthas sp), and various Lumbricus sp worms (eg Lumbricus rubellus) - which have a voracious appetite for fallen leaves and other carbon-rich organic matter. Rapidly consuming this sort of ground cover in forests and other natural environments can have a negative impact on local ecosystems, especially in regions where a lot of earthworms weren't previously living. Bottom-line, you can rest easy knowing that if you are providing the requirements that composting worms in outdoor systems need, they won't leave in search of greener pastures.

"I have 3 rotary composters for ease and to prevent rodents. They can get quite hot. Would they work for worm compost? As I have no animals to add manure to my compost. So looking to worms to provide what manure would. Is that realistic?"

The good news is that separating worms from the compost is relatively easy with a basic light harvesting method. Ideally, you should dump out the contents of your bin into a large, shallow tray (something like a black mortar mixing tray can work very well) sitting in a brightly lit location. Start by gently breaking up the worm-rich material with your hands or a small garden fork. Spreading it out as much as you can will expose more surface area and help to dry everything out. If it is particularly wet (eg. when using a tub system with no drainage), you may actually want to place some dry cardboard, or another absorbent bedding material down in the bottom of the tray before dumping in the contents of your bin. One other helpful strategy can be to set up a fan next to the tray so you can blow air over the surface of the material. Not only will this help to dry it out, but it will also help encourage the worms to keep diving down. At this point it becomes a process of letting the upper layers of compost dry and then gently scraping them off. "Roughing up" the surface (gently) with the hand fork between removal sessions can help a great deal (and also tends to send the worms further down). This process can take a bit of time - we recommend leaving your tray to sit for a period of time, while you do other things, in between scraping sessions. But in some cases - eg working on a series of trays outdoors on a nice sunny day - you'll be amazed by just how much compost you can harvest in a relatively short period. Once you get down towards the bottom of your tray(s), you'll start to find more and more worms, and at some point you should just transfer your remaining gob (along with remaining habitat/compost) over to a new system.

  • How to Separate Worms from Their Castings

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    This is Part 2 of a 2-part harvesting vermicast series. Be sure to also check out Common Questions About Harvesting Worm Castings. When it finally comes time to put your beautiful black gold to...

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