Frequently Asked Questions

Considering the world of worm composting?

What to expect when you’re expecting: Getting ready for your worms.

Now what? Getting your worms settled in.

They’re alive and staying alive! Ongoing maintenance.

Down the Road.



Why choose vermiculture?

Why should I compost with worms? Why would I want to?

Worm bins and vermicompost are an important part of long-term sustainability in your house and garden. They reduce the amount of food waste being sent to landfills, the fossil fuel being used to transport and process waste, and the resources needed to produce and import soil amendments into your garden. Worms are a fun and easy way to fight waste and global climate change, and are an excellent teaching tool for children.

Worm composting offers a unique opportunity for urban dwelling folks to compost their waste (even in their tiny apartments) without producing a stinky-garbage smell. It does take a little while to get the hang of it, but once you do you’ll be surprised at what your worms can handle. In about 1 cubic foot of space you can cut your trash outgo by at least 30%. The resulting worm castings are much more powerful as a soil amendment than traditional compost. And let’s face it, worms are just fun! There’s something awesome about maintaining an animal usually thought of as unnecessary and watching them grow and feed.

Worm composting, or vermicomposting, involves the breakdown of food waste into a nutrient-rich compost through the action of worms and other microorganisms. Red wigglers (Eisenia fetida) are the most commonly used variety of composting worms because they are surface dwellers that live in rich organic material and can eat around half of their body weight a day in food waste. From this waste they produce castings, a form of excretion that is incredibly nutrient rich and can be applied to gardens and farms. These castings have been referred to as “black gold” because of the value it can add to your food system.

Organic gardening keeps harmful chemicals out of our bodies, our water supply and our children and pets. The more we understand about waste and where our food comes from, the healthier and more sustainable we can make our communities and our lives. Thank you for investing in the future of our planet!


Where will my worms live?

Red wigglers are very happy in worm bins. That’s because they are epigeic, which means they like to live close together, unlike other earthworm species. Bins can take a variety of forms, but are most commonly made out of plastic or wood. We sell plastic stacking worm bins on site for $90 that are available for purchase during our open hours or at workshops. If you do not live locally, check your local nursery, large retailer, or purchase online.


How do I build my own worm bin?

See our Build a Bin page for more information about how to build your own worm bin.


Can I put my worms in my garden or compost pile?

Red wigglers eat the microorganisms that break down plant matter. A garden bed always has some decomposing matter in it, but usually not a lot. We do not recommend putting large quantities of red wigglers in your garden, though the few that end up there when you add your vermicompost will fertilize the soil as they munch through what they find. Once they run out of food in your garden beds, they will take off for greener pastures.

Red wigglers cannot live in a hot compost pile; if you are flipping your compost in order to decompose your waste, temperatures will ideally be as high as 150 degrees fahrenheit! Worms like it between 55 and 77 degrees, so this is way too hot for worms. If you are throwing your food waste in an unmanaged “cold” compost pile, adding worms may help the process. They will find the food that suits them. However, if conditions are not ideal, they may find more suitable housing elsewhere.


Once I have my bin, what do I do?

Set up your bin a few days in advance of receiving your worms. While this isn’t essential, it allows time for microbes to grow (which are what the worms are actually eating, not the food itself) on your two worm bin ingredients: bedding and food scraps. It’s a friendlier environment for the hungry worms and makes for an easier transition. Also, throwing a handful or two of soil into the bin will help get the microbial action started.


What makes good worm bedding?

We recommend using newspaper that has been torn into thin strips (shredders work great!) This is a free, waste-stream material. Only use newsprint which uses soy-based ink (most newspapers use soy inks.) Do not use shiny advertisements or magazines as worms will stick to the surface and the ink may be toxic.

You want your bedding to be fluffy, like packing material. The goal of the bedding is to keep the food scraps aerated and oxygen rich, and to absorb extra moisture. If the bin is too wet and dense, the material may go anaerobic. A different set of microbes live in this oxygenless environment, and your worms will die. Anaerobic conditions are also bad for your garden.

The one down side of newspaper is that you have to use a lot of it and replace it often as it is easily condenses when wet. If you are looking for a lower-management bin, another good bedding option is coconut coir. Coconut coir is the fiber on the outside of coconuts and will last longer and create better airflow than newspaper. Most nurseries cary coconut coir bricks and you can pick one up for between $4 – $10.

Ruminant manure (grass-eating animals such as goats and horses) also makes good bedding (and food!) Urban Worm red wigglers come to you from giant piles of horse manure that serves as both their bedding and main source of food. Just make sure you let the manure go through a hot compost cycle first so you don’t cook your worms. You’ll know its ready to use when the manure is dry and capable of absorbing moisture.

There are other options out there such as cardboard and peat moss, both of which have some serious downsides. Cardboard is a great bedding supplement because the worms can mate in the corrigated areas.

The problem is that it isn’t very fluffy so it doesn’t provide the necessary oxygen flow, so you’ll need to spend a decent amount of time shredding it. The worms also love peat moss and it’s physical properties make great bedding. The problem here is that peat-moss is a non-renewable resource.

Whichever bedding you choose will eventually breakdown and become part of the organic matter in the castings.


How do I setup my bin?

Things you’ll need to get started: 
A bin
Bedding materials
A nice, shady place to put your bin
Scraps to feed the worms

Below are directions for the lasagna method. It is the preferred method of Urban Worm, but there are lots of ways create a happy, healthy home for your worms!

1. Once you  decide on the type of bin you want to build or buy, you should set it up a few days in advance of receiving your worms. While this isn’t vital, it allows time for microbes to grow (which the worms actually eat) on your bedding and food scraps. It’s a friendlier environment for the hungry worms and makes for an easier transition. Make sure that you have air holes in the lid of your bin to allow for sufficient air flow. Finally make sure that the bin is completely out of the sun!

2. Fill the bin 1/4 full with moistened shredded paper, cardboard, coconut coir or your choice bedding. Worms will eventually eat the bedding, too.The moisture level of the bedding should resemble that of a wrung-out sponge: not sopping, not dry.

3. Put a layer or a pile of food scraps on top of the layer of moistened bedding. You can wither spread a layer of food scraps, or put them the food scraps over to one side of the bin. The benefit to spreading out your scraps at least a bit is that it helps prevent anaerobic conditions during decomposition. Throwing in a few handfuls of soil and this stage will help to inoculate the bin with beneficial microbes.

4. Put a nice layer of moistened bedding on top of the food layer. (It is important to note that this is probably the only time you will need to add moist bedding. Generally bedding needs to be added to soak up the moisture being released from the food scraps.)

5. Put a thick layer (several inches) of dry bedding on top of the whole worm lasagna.

6. When your worms arrive, gently open the package. Pull back some of the dry bedding in your bin and gently turn out the worms into the bedding into one pile. Don’t spread them out; they are probably somewhat traumatized from the journey and will venture out in their own time. If there are worms left in the package, you can leave the package on top of the bin for a day, pointing down with a clear path. Because the worms do not like the light or dryness of the top layer, they will burrow down relatively quickly.

7. Leave the lid off for at least a day to make sure the worms stay down low. If/when you put the lid on, and then you check on your worms and they’re crawling along the lid, you don’t have enough air flow. Drill more holes.

Give your worms a few days to settle in before bothering them again. When it looks like they are making it through the scraps, you can start to add more. When you feed your worms, dig down and make sure to cover up the food scraps well. We like the layering approach to worm composting because we know that in between each layer of food is a nice cushion of bedding to allow for air flow. As the food breaks down the liquid will moisten each later of dry bedding below it.


Where do I put my bin?

Worms survive best in temperatures ranging from 55 to 77 degrees. That doesn’t mean the air outside has to be that temperature, only the inside of the box. On cold days, the microbial action will keep bin temperatures well above the outside air temperature. Always keep your bin in a shady spot because direct sunlight is the fastest way to a bin that is far too hot for the worms. Even on a day reaching into the 100s, the worms should be alright if they are in a nice shady spot. A good way to test is to touch the bin. If it’s hot to the touch, they need to be in a cooler location.

There are lots of good places for your worm bin, both inside and out of your house or apartment. They can be in garages, basements, laundry rooms, under outdoor stairs, next to a shady back door, on balconies and porches or under your kitchen sink. Basically, they need to be out of direct sunlight and somewhere where you won’t forget about them!


What will I receive when I make a purchase from Urban Worm?

When you open your package or worms, you will find one pound of red wigglers (approximately 1000 worms) squirming around in decomposing horse manure and old coffee grounds (which is their food and bedding when they are here at our farm). You may find worm larvae or other little critters that are helping the worms do their job. This is totally normal!

Inspect your bag for live worms. Even if it doesn’t look like 1000 worms, we promise they are there! If you don’t see any worms, or if you’re concerned your worms have died on arrival, please call us and we will be happy to send you a replacement. (We do our best, but sometimes worm lives are unpredictable!)


What do I do with my new worms?

Once your have set up your bin, lift up the top layer of bedding and dump your worms directly onto the food layer and then gently cover the worms back up with the bedding. You don’t need to spread them around–they will be slightly traumatized from their trip and need a few days to acclimatize. Don’t disturb the bin for 3-4 days.


What can I expect in first few weeks?

Not too much actually. They will not be eating at their full potential for about a month, given ideal conditions. Don’t disturb them for the first few days that they are in your bin, they need a little time to acclimate to their new surroundings. After about a week has passed, use your hand or a trowel to lift up the bedding and food. You should see some worms wriggling through the food and bedding. If not, see Troubleshooting my bin: common problems. Worms always try to avoid sunlight, so if your worms squirm like crazy and burrow down away from the light when you peel back the bedding, you’ve got happy, healthy worms!


What should I feed my worms?

Red wigglers don’t actually eat your food, they eat the microorganisms that eat decomposing organic matter. You can feed them the majority of your kitchen food scraps. Non-citrus fruits, vegetables, tea bags, coffee grounds and filters and crushed eggshells are great. Manure from horses, cows, and rabbits are good as long as you let them compost a little on their own first so they won’t be so hot when added to the worm bin. Grass clippings and other leafy yard waste is also fine. Paper towels and other soiled paper products are also acceptable. Some notable exceptions:

1. Limit onion and garlic skins. They skins are carbonaceous and break down very slowly. It will be a long time before they are ready for the worms and could start smelling before they become worm food.

2. No citrus. Citrus peels contain limonene, which is toxic to insects. Read More Here

3. No meat or dairy. It attracts rodents, and won’t decompose at the same rate as the vegetables so may start to smell.

4. No pet or human feces. This kind of bacteria is bad for worms and gardens.

5. No oil, and limit oily food. A little cooked food is OK, but worms breathe through their moist skin. Oil will smother them.

6. No woody plant material or pits. It won’t break down quickly enough.

7. No non-organic matter. Plastic, metal, soap or other non-food items do not belong in bins.


How do I get food for my worms?

The simplest way to feed your worms is to put your worm-appropriate scraps in a container on your kitchen counter (we use a Costco-sized pickle jar) and dump them into your bin every few days. Covering your food scraps while they await their wormy fate will help control fruit flies and smells in your kitchen and in your worm bin.

There are variations. You can freeze your scraps to help control fruit flies in your kitchen. You can also blend your food scraps before adding them to your bin. This will create more surface area, allowing microorganisms to break the food down more quickly, which in turn will allow the worms to turn it into castings faster.

Your choices will depend on the goal of your worm bin. Are you just trying to divert food waste from the landfill? Go simple: just dump your food in the bin. Are you trying to raise lots of big fat worms for fishing? Try different foods and pay attention to what your worms like. Are you trying to get as much vermicompost as possible for your garden? Blending your food will get you faster results.


Is it possible to over or under-feed my worms?

Red wigglers will adjust their populations based on their conditions. If they have lots of space and lots of food, they will reproduce more rapidly. If they are feeling cramped and hungry, they will reproduce more slowly. If you feed your worms a somewhat regular supply of food on a somewhat regular basis, they will adjust their populations accordingly and reach carrying capacity.

The only danger in overfeeding is that your food may begin to rot before it is broken down by microorganisms, which will cause it to smell. If you have more food than your bin can handle at the moment, increase the amount you feed day to day slowly so your population has time to adjust. You can also cover your food with more bedding to help absorb the smell.


How often do I feed my worms?

Ideally you will feed your worms every 2-4 days. However, worms are flexible. You can feed them as often as every day or as infrequently as every other week, depending on your needs and goals for your worm bin. If you need to get your food waste off your counter every day, go for it. If you go on vacation, your worms will be fine for a couple of weeks without care–assuming you give them a big helping of food waste before you leave, and their bin doesn’t get too hot or dry. The take-home point is that you don’t want to be feeding them so infrequently that they eat their castings and not so frequently that the food rots in the bin.


How do I feed my worms?

If you have a stacking bin, use the “lasagna method,” alternating between a layer of food and a layer of bedding. Start with your bottom most tray, which will be your first tray with holes on the bottom. Do not start your bin in the very bottom of your bin with no holes–this tray is intended for catching extra moisture or leachate. Once your bottom tray is full, put a new tray on top and continue with lasagna feeding: food, bedding, food, bedding.

If you have a single-level bin, use the “pocket feeding method.” That is, dig down into one corner of your bin and dump your food there. For your next feeding, move a few inches over from your first feeding location, dig a little hole, and feed there. In this way, you will work around the bin, which will make harvesting easier later. If your bin is too small for this, simply feed the bin in halves. Feed one side for a couple of weeks, then feed the other side.

Whichever method you use, make sure to include plenty of bedding. Every time you add food to the bin, cover it with bedding to soak up moisture and to reduce pests and smell.


How do I know my bin is healthy?

Stick your hand or a trowel into your bin to look at different sections of your bin. You should see lots of worms. They should look moist, but they should not be sitting in pools of water. Your worms should be 1-4 inches long and plump. As you poke around, they should be very active–wriggling around and shying away from the light. The bin should not have an unpleasant odor. If worms are collecting in one area, this could indicate that they very much like what is in that area, or that they are stressed. Worms collect in a ball in response to stress.

It’s a good idea to be in your bin at least once a week. Poke around in your bin as you feed to check for these conditions. If you think something is wrong, act immediately.


What is all that moisture collecting at the bottom of my bin?

The moisture that collects at the bottom of your bin is called leachate. When food breaks down, its cells burst and release liquid.

No matter what type of bin you have, there needs to be a way for the leachate to escape. If liquid sits at the bottom of your bin, it can cause the worms to drown and create an anaerobic environment.

If you have a stacking bin, you’ll notice that all of your trays have holes at the bottom, except for the very bottom layer. This layer is for collecting excess moisture. Homemade bins usually have holes at the bottom the allow liquid to escape into a tray of some sort.

If you have more than a centimeter or two of leachate a week, your bin is too wet (Troubleshooting my bin: common problems.) A well managed bin may not have any leachate at all.


Troubleshooting my bin: common problems

A. Fruit flies. There is nothing wrong with fruit flies–they are just annoying, and you certainly don’t want them in your house. Cover your bin with a sheet (we use a fitted sheet so it stays on better) to interrupt the reproductive cycle of the flies. They lay their eggs in the bin but leave to find a mate. Also, use more bedding on top, so the bin isn’t as appealing as a breeding ground. You can also try freezing your scraps before feeding the worms. This will kill any eggs that are in your food.

B. Ants. Create a moat around your worm bin: the ants won’t be able to cross the water. If your bin has legs, put the legs in bowls of water. If your bin has a flat bottom, support the bin on bricks or whatever you have handy, and place those bowls of water. Or you can place something shallow such as a tupperware lid (upside down) on the ground, fill that with a bit of water and place your bin on a brick on that. Remember: drainage is essential to worm bin health. Make sure your drainage holes are not blocked by your moat.

C. Mold. Mold is a type of fungi, which is one of the ways organic matter breaks down. There is nothing wrong with having it in your bin for the worms’ sake, but you can avoid it if it grosses you out or if you are allergic to it. Mold means you are feeding too much food too quickly, and the worms can’t increase their populations fast enough to keep up. Cover the food with more bedding to help keep the spores from spreading, make sure your bin isn’t too wet, and take a feeding hiatus for a few days. Increase the amount you are feeding to your worms slowly over a couple of months so they can adjust their population. You can freeze your food waste if you don’t want it sitting around, or compost it in a hot compost pile.

D. Smell. Your bin should be pretty neutral smelling. If you can smell your bin when it’s closed, something is awry. The first thing to check is moisture. If your bin is too wet, it is possible it has gone anaerobic, which means there is no oxygen. This is an unhealthy environment for worms, and not the kind of microorganism activity you want in your garden. Stir in lots of new dry bedding to absorb moisture and create airflow. While newspaper is a great waste-stream option for bedding, it can easily compress with lots of wet food waste, so be diligent with your bedding use as you feed your bin. Smell could also be due to mold. Make sure your drainage holes aren’t plugged up.

E. Rodents. Rodents are attracted to meat, dairy, and starch. Minimize the amount of cooked food you put in your bin, and completely avoid any meat or dairy products. Egg shells are great, but if you are having trouble with rodents, try washing them out first. Make sure your bin is tightly closed and use heavy objects or a bungy cord to keep the lid in place.

F. No worms! Red wigglers are epigeic, which means they like to live close together, making them the ideal candidates for life in a bin. However, if the bins aren’t suiting their needs, they will have no reason to stay and will try to escape. If they can’t get out, they will be under great stress and will probably die. Non-ideal conditions include too hot, too cold, too wet, too dry, too acidic, or anaerobic. If you don’t see any worms, unfortunately, it’s time to start over.


How do I harvest castings?

After you get a good accumulation of castings you will want to remove them to put in your garden without losing your worms. Worms will not hurt your garden (in fact, they may even help a bit) but the goal is to keep the worms in the bin so they can keep doing what they do best.

If you have a stacking bin, it is quite easy. Follow feeding instructions. Once you have had a second tray filled with food and bedding for a couple of weeks, most of your worms will have migrated upward to the new tray, leaving your original tray devoid of worms but full of castings. Remove those castings and your tray is ready to be filled with new food waste and put on top of the stack.

If you have a single-layer bin, you are probably feeding with the pocket method (See How do I feed my worms?) and should therefore use the “pyramid method” to harvest. Find the areas that you fed longest ago and are the most broken down and remove them, placing them on a tarp or other surface in a pyramid shape in the sun. Worms are light-averse, so will dive below the surface to escape the sunlight. Wait 5 minutes and remove the top layer of castings. Continue this process until all your worms are together at the bottom of your pile. Return your worms to your bin.


What do I do with castings?

Castings (worm poop) or vermicompost (a combination of worm poop and decomposed organic matter) are incredibly high quality composts, full of key soil nutrients and a complex eco-system of microorganisms. Healthy soil is the key to healthy plants, and vermicompost is an investment in the long term health of your soil.

Here’s are just some of the things it will do for your garden:

1. Improves soil structure and porosity–creating a better plant root environment
2. Increases moisture infiltration and permeability, and reduces bulk density of heavy soils–improving moisture infiltration rates and reducing erosion and runoff.
3. Improves the moisture holding capacity of light soils–reducing water loss and nutrient leaching and improving moisture retention
4. Improves the cation exchange capacity (CEC) of soils
5. Supplies organic matter
6. Aids the proliferation of soil microorganisms
7. Supplies beneficial microorganisms to soils and growing media.
8. Inoculates the soil, helping to fight pests and diseases naturally throughout the life of the plant.
9. Allows plants to more effectively utilize nutrients, while reducing nutrient loss by leaching.
10. Enables soils to retain nutrients longer.
11. Contains humus–assisting in soil aggregation and making nutrients more available for plant uptake.
12. Buffers soil pH.

Use vermicompost when getting ready to plant to ensure a rich soil environment for your new seeds or starts. Incorporate a layer one to two inches deep in beds, or a ratio of one part vermicompost to two parts soil in a pot. Top dress every two to four weeks for continued soil health.  Vermicompost can also be used to make a great compost tea for foliar feeding.

Vermicompost is especially important in nutrient-limited environments such as planter boxes and potted plants, where every bit of nutrition needs to be available to the plant, and where soil depletion is rapid.Read More Here


What do I do with leachate?

Leachate has been both extolled as a phenomenal liquid fertilizer and warned against as dangerous for your garden. We recommend treating your leachate with caution, as it can contain harmful microbes produced in anaerobic conditions. Unless you are experienced with liquid fertilizers in general and leachate in particular, always test your leachate on a bit of grass before using it on your plants. We do not recommend using leachate on edible plants. Leachate is not the same thing as compost tea. (See What is compost tea and how do I make it?) Aerating it as part of a compost tea will render it safe.

Many people do use leachate on their plants successfully, but it is not a guarantee. Ye be warned.


What if I have more waste than my bin can handle?

You have a few options. Red wigglers will adjust their population to fit their space and food resources, so if you have more food than will fit in your bin, split your worm population in half and start up a new bin. You can alternate feeding between the two. If you have a stacking bin, you can just add more trays.

You can also start a compost pile. Hot compost piles are easy to build–there are many resources online to help you. Give your worms only their favorite treats, and throw everything else in the hot compost
pile. Even a cold compost pile will do the trick (though it works much more slowly).

You can always participate in your city’s green waste composting program, if available. Or find a local community garden that is making their own compost.


What is compost tea and how do I make it?

Compost tea is a liquid fertilizer made from compost that is misted on plants for foliar feeding (giving a plant nutrients to be taken up through the stoma in the leaves) and to promote disease resistance. It is also applied to soil as another form of soil nutrition.

Some compost tea experts say not to even bother with it unless you can look at it under a microscope. Some people give complex recipes with many ingredients. But as long as you have the basic components and manage it properly, you can brew a helpful amendment.

The basic components of a compost tea are compost, protein, sugar, and oxygenated water. The more complex your compost ingredients, the more nutrient- and microbe-complex your tea will be. You can also control your ingredients for the different needs of your plants during their life cycle, but that is beyond our scope here.

For an easy compost tea, here is a simple recipe recommended by Rene Zazueta, a local master gardener, expert composter, urban garden teacher and activist:

1. Fill a plastic trash can or 5-gallon bucket with tap water. Dechlorinate it by letting it sit overnight.
2. Fill a porous bag such as a burlap sack or pillow case with the compost of your choice. Urban Worm’s vermicompost or castings from your own worm bin will work great! It is important to note that all compost should be finished, meaning the breakdown process is complete.
3. Suspend the bag in the bucket of water.
4. Add two tablespoons of molasses and two tablespoons of fish emulsion (available in nurseries) to the water.
5. Add dry straw or other plant material; some bacteria prefer a surface area to grow on.
6. Aerate with a fish tank bubbler for three days. Stirring is a cheaper option for aeration, but it must be stirred very regularly, and especially vigorously before application.
7. Dilute 10:1 with water before adding to your garden. You can use your drip irrigation, a spray bottle or a watering can.

Rene uses nothing but city compost and home-brewed compost tea in his phenomenal Berkeley garden. He has been perfecting the art of compost tea for many years, and this information is based on his experience and research. If you would like a more complex compost tea, Rene recommends:

1. Dechlorinated water
2. Goat, llama and/or horse manure (each animal produces a different microbial population and all animal manure must be aged before using in the garden or in a tea)
3. Compost (only use cured compost, ideally including chicken manure)
4. Vermicompost, worm castings or leachate
5. Molasses (or other sugar source such as old fruit or jam)
6. Alfalfa (pellets or straw)
7. Fish emulsion (or other protein source, like the beans you forgot at the back of your fridge)
8. Top litter from forest (to inoculate your tea with local microorganisms and fungi)
9. Fresh straw or foliage

Some things to remember when brewing compost tea:
-Your ingredients must be sufficiently aerated in order to produce a healthy tea for your plants
-While you may not make a perfect tea right away, it is hard to create something that will hurt your garden. Your biggest concern is a low pH, which you can control for by adding a handful of ash (not charcoal, which is a carbon source).
-Never add raw manure to your compost tea.
-These recipes create a bacteria-dominant compost tea. Vegetables prefer bacteria-dominant soil (as opposed to trees, which prefer fungus-dominant soil).
-Soil microbiology is an incredibly complex science and there are many ways to make compost tea. This is barely a taste of what is possible to know about the universe of microorganisms living in your soil.


What if I have a question that wasn’t answered here?

Call or email us! The Urban Worm Team is always available to answer questions and help you troubleshoot.
phone: (510) 649-1595 x 305