Vermicomposting 101: How to Make a Simple Worm Compost Bin

Come learn how to make a DIY worm bin – video included! It’s easy, inexpensive, and quickly turns food waste into amazing nutrient-rich compost that will help your garden thrive. This post will explore the basics of vermicomposting (the term for composting with worms) along with how to start a simple worm compost bin or worm farm. We’ll also cover how to properly maintain your worm bin, including tips for hot or cold weather, what to feed it and how often, harvesting worm castings, and more.

Of the all the ways we compost at home, vermicompost is by far my favorite. When people ask why or how our gardens look so lush and healthy, I blame the worms! We’ve had a worm farm for almost 15 years now, even when we lived in an apartment.

We buy our compost worms from Uncle Jim’s Worm Farm.

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What is Vermicomposting?

Vermicomposting is a style of composting with the assistance of worms. The prefix vermi- literally means “worm”. When added to a compost bin or pile, worms greatly increase the rate of decomposition. This means you’ll have ready-to-use compost in no time!

In addition to the quick turnover, there are a number of other benefits to vermicomposting:

• Worm bins are very compact and tidy compared to other compost methods, making it easy to vermicompost in a wide variety of living situations or spaces. Contrary to popular belief, they do NOT smell bad if they’re well-maintained!
• Worm farms are a fantastic and sustainable way to dispose of food waste at home, which diverts waste from the landfill and reduces carbon emissions.
• The final compost that comes out of a worm bin (called worm castings) is arguably one of the best types of natural fertilizer around! So much so, vermicompost is often referred to as “black gold“.

What are Worm Castings?

Worm castings, aka vermicastings, is a fancy term for worm poop. Rich in nutrients and beneficial microbes, worm castings are a wonderful well-balanced, slow-release form of natural fertilizer!

As worms eat and break down the food scraps, garden trimmings, bedding and other organic matter in a worm bin, the nutrients found in those materials become highly-concentrated in the excreted worm castings. Even better, the nutrients become more bioavailable, meaning the plants can make use of them more readily! Yet worm castings are also very gentle and cannot “burn” your plants like other animal manure or fertilizer can.

But that’s not all! When added to garden soil, worm castings also increase soil aeration, drainage, biodiversity, and water retention. Cornell University refers to worms as a living soil amendment. Learn more about the benefits of worm castings for plants here.

Supplies Needed

Here’s a quick list of the supplies you’ll need to start a worm bin, with further explanation of each item below.

• A simple bin with a lid, such as a large durable plastic storage tote.
• Recommended: a drill and 1/4″ bit to add air holes to the bin.
• Dry bedding material, such as shredded newspaper, coco coir, dry leaves, grass clippings, shredded cardboard, or straw.
• Compost worms
• Grit or dirt
• Food or garden scraps

1) A Bin or Tub

There are plenty of neat worm-tower systems out there, but inexpensive plastic storage bins or totes work perfectly! It’s what I’ve always used. Choose one that is durable, heavy-duty, and made of non-transparent plastic. (Worms like the dark.) Also ensure the top lid area doesn’t have any holes where rain can seep in.

The blue tub shown in this example is 35 gallons, which works quite well. We’ve made worm farms as large as 55 gallons and as small as 15 or 20 gallons. If you may need to move your worm bin on occasion (such as to protect it from freezing in the winter – discussed more to follow), keep mobility and weight in mind when choosing your bin size.

2) Bedding Material

Worm bin bedding is the bulk dry carbon material or “browns” in the bin, which is essential to balance the wet food waste or “greens”. Good worm bin bedding options include shredded newspaper, rehydrated coco coir, dry leaves, dry grass clippings, brown paper bags, shredded cardboard, or straw. Avoid bleached white paper or glossy paper. Peat moss also is not recommended for worm farm bedding since it’s too acidic.

Bedding is used both to start a worm compost bin and added later during routine maintenance. We use a combination of coco coir and shredded newspaper to set up our bin, and then switch to newspaper and dry leaves thereafter. We also invested in a basic paper shredder to routinely shred newspaper for our bin.

3) Compost Worms

The most popular kind of worms used in worm bins are Eisenia fetida, commonly known as “red wigglers“. We get ours from Uncle Jim’s Worm Farm. You could also check to see if you happen to live near a worm farm, and make a little field trip out of going to pick some up!

I recommend starting with 1,000-2,000 worms (about 1 to 2 pounds) for a 35-gallon bin or larger, and half that for smaller bins. Under the right conditions, they can double their population in just 90 days!

4) Dirt or Grit

In addition to bedding, worms need a little natural grit to help their digestive track. We add few small scoops of our native sandy soil to our worm farm. If you have clay soil, add some potting soil instead.

5) Food Scraps

Last but not least, you’ll need some kitchen scraps or garden trimmings to feed your worms. Do not put moldy, rotten food in your worm bin! Keep reading below to learn more about “feeding” your worm farm, including the best things to add, materials to avoid, how much, and how often to feed it.

Location: Where to Keep a Worm Bin

Ideally, a worm bin should be kept in a sheltered location that is protected from extreme temperature swings. For instance, in a shady spot in the yard, tucked along a shaded wall or fence, on a covered porch, or even in a laundry room or other indoor location. It may be necessary to move your worm farm to different locations depending on the time of year.

Red wiggler compost worms are most happy and active at temperatures ranging from 55 to 85°F. Outside of that temperature range, they will slow down, eating and reproducing less. Therefore, you may need to feed your worm bin less often during cold winter months to make up for their decreased activity. In extreme cold or heat, they may die.

Freezing temperatures below 35°F or hot temperatures over 95°F can kill your compost worms.

However, the outdoor temperature is not the same as the internal temperature inside your worm bin! A well-maintained worm farm with fluffy, healthy bedding and castings can naturally buffer and protect itself from temperature swings (to some extent). A compost thermometer is very handy for monitoring the temperature inside the bin.

Here on the temperate Central Coast of California, our worms happily live outside year round with no added protection. Yet we have experience vermicomposting in much more challenging climates too! We’ll talk about easy ways to protect your bin from excessive heat or freezing conditions in the maintenance section to follow.

Instructions to Make a Worm Bin

1) Add Air Holes

The first step to make a worm bin is to add some air holes to your chosen container, which helps with fresh air exchange and prevents the bin from getting too hot or stagnant. Using a quarter-inch drill bit, we add a couple dozen air holes around the sides of the bin near the top. See photo below. Be sure to make the holes small enough to keep pests (e.g. rodents) out!

Should I add drainage holes to my worm bin?

No, there are NO holes in the bottom of this DIY worm bin. A well-maintained bin does not need drainage holes since it shouldn’t get overly wet. We’ll keep the moisture and consistency on point with the right balance of bedding to food (discussed in the feeding/maintenance section to follow). Plus, if you add holes in the bottom, the worms will escape the bin!

Some pre-made worm farms come with a drainage catchment, but the liquid that seeps from an overly wet bin is considered leachate, not true “worm tea” or “compost tea”. Leachate is stagnant and anaerobic (meaning without air) and lacks many of the beneficial microbes found in proper compost tea. See our guide on making aerated compost tea with worm castings to learn more.

2) Add Bedding

Next, it’s time to partially fill your DIY worm bin with “brown” bedding material such as dry leaves, shredded newspaper, cardboard, dry grass clippings, straw, and/or cardboard. The amount doesn’t need to be exact, but aim to fill the bin about a quarter full. The more fine the bedding material is, the faster the worms can break it down. For instance, it’s better to use smaller bits of cardboard instead of large chunks.

In this example, we used a mix of shredded newspaper and coco coir. I really like using coco coir bedding to start a worm bin because it’s has perfect fine fluffy consistency and excellent moisture retention. Unlike peat moss, coco coir has a neutral pH – ideal for a worm farm. See more details about using and rehydrating coco coir below.

3) Dampen Bedding

Now, lightly moisten the bedding with a modest amount of water. A happy, healthy worm compost bin should always be slightly damp but never soggy. An easy way to remember is: the ideal consistency is that of a wrung-out sponge. Start small, stir, assess, and then add more water if needed. It’s easier to add more than take it back!

Worms love damp environments, but also need air because they breathe through their skin. With too much water, they can and will drown. That’s why you see earth worms coming to the soil surface when it rains – to get air! Plus, an overly wet worm bin is how they get gross and stinky.

Rehydrating coco coir

Coco coir comes in dehydrated bricks and must be rehydrated and fluffed up before adding it to your worm bin. We already had a 10-pound brick of organic coco coir on hand, but I knew it was too much so I cut in half with a saw and only used half (or about 5 pounds for a 35-gallon bin). It would be easier to buy several smaller 1-pound bricks instead.

To rehydrate coco coir, I recommend putting it in a separate container (just in case you don’t want to use it all) and then add just a little bit of water at a time. Remember, the goal is to create damp bedding, but not sopping wet! So add some water, wait for it to absorb, then add more as needed until it’s all broken up and nicely moistened.

4) Add Worms

It is important to have your worm bin and bedding ready and waiting before your worms arrive so you can get those buggers put to bed straight away! Like any of us would be after a long road trip or flight, they’ll probably be a bit cranky upon arrival and need a snack and a nap, pronto.

Upon arrival, dig a little hole in the damp bedding. Add some food as explained below, dump in the worms, and cover them up with more bedding. Finally, we like to add a damp layer of newspaper on top, which helps to keep them in the bin, explained more below.

Why are my worms trying to escape the bin?

When you first set up your new worm compost bin, it’s not uncommon for worms to crawl up the sides and try to get out. They’re just a little wigged out by their new environment. To help keep ‘em in and happy, their environment needs be how they like it: the right moisture level in the bin (damp but not soggy), enough of the right food to eat, and plenty dark.

A trick to help prevent worms from crawling out of a new bin is to place a few sheets of damp newspaper on top of the “soil” mound inside the bin. Go back and check the bin after a day. Ours will sometimes cluster around the lid and handle portion of the bin. Put them back under the damp newspaper.

Fast forward a couple weeks. If worms are still trying to escape from an established worm bin? That may be a signal that there’s a problem with the bin, like not enough oxygen, too much acidic food, too wet of conditions. Try fluffing up the bin with fresh bedding and/or food, or adjust the moisture level as needed.

5) Feeding a Worm Bin

Now it’s time to start feeding these hungry little babies! The right type and amount of food is key to maintaining a healthy, happy, and odorless worm compost bin. First let’s talk about about what to feed them, and then we’ll discuss amount and frequency.

When you set up a new worm bin, add just a few handfuls of food at first. Check back in a few days to see how much they’ve eaten and go from there.

What Food to Add or Avoid

Worms, believe it or not, do have some preferences in regards to their food. Certain things need to be avoided altogether – for their health and the health of the compost bin.

Things that are good or okay to put in worm compost bin include:

• Almost all fruit and veggie scraps (see the few caveats in the “no” list)
• Tender garden trimmings
• Eggshells, especially crushed or ground!
• Spent coffee grounds
• Spent loose-leaf tea or tea bags (staples removed)
• Sourdough starter discard (in moderation, since it’s wet and goopy!)

Avoid adding these things to your worm bin:

• Meat or dairy products
• Animal manure
• Citrus (it’s too acidic, we want a well-balanced neutral pH in the bin)
• Processed foods
• Moldy, rotten food
• Spicy foods (we found our worms won’t eat hot peppers or radish greens… weirdos)
• Limit amounts of bread, pasta, or other starchy foods

How Much and How Often

Under the optimal conditions, worms can eat their body weight per day! That means if you started out with 2 pounds of worms, they could theoretically eat through 2 pounds of food scraps per day. As their population grows inside the bin, they can consume even more. When it’s cold outside, they slow down and consume far less.

We prefer to feed our worm bin on a weekly basis, storing up food waste in a compost crock under the kitchen sink between feedings. The crock has a carbon filter, so it doesn’t get smelly or attract fruit flies.

I suggest to err on the conservative side. If you add more more food than your worms can eat in a reasonable amount of time, it will rot and go anaerobic instead. That will result in a stinky, gross bin… and no one wants that!

With time, you’ll learn to judge how much food your worms can eat in a week. If after a week later there is no food left at all, you can increase how much you’re giving them. Or, even introduce a mid-week snack. However, if there is a bunch of food leftover, you should scale back and feed them less quantity each week.

How to Feed a Worm Bin

• Before adding food each week, carefully stir and fluff all of the contents of the worm bin to introduce air, assess how much food they’ve eaten since last week, and generally check the condition of the bin.
  
  
• To add food, gently dig a hole in the bedding, put food into the hole, and then cover it back up. It’s always good to bury the food in your worm farm by at least a couple inches of bedding, which helps the worms find it more quickly and reduces odors or flies.
  
  
• You don’t have to cut up food into smaller bits, but it does help them break it down faster! I suggest cutting up large chunks of really dense material, like the butt end of a cabbage.
  
  
• In an established worm farm, it is best practice to add a handful of “browns” (bedding) each time you add more food scraps, or at least once every other week. The dry browns help to offset the higher nitrogen and moisture content of the “greens” – the food or garden waste. This is essential in keeping a well-balanced, healthy bin that doesn’t get stinky and gross! For ease, we always keep a bucket of dry leaves or shredded newspaper nearby.

A nasty-smelling worm bin is usually the result of too much food, too little browns, too much moisture, and too little air.

General Maintenance

Thankfully, worm farms are pretty fuss-free once you get the hang of them. The main task is to keep them routinely fluffed and fed. Yet it is important to keep an eye on the moisture content as well as extreme temperatures to keep your worms safe and happy.

Moisture and air

In addition to the right balance of food to bedding, the key to maintaining a healthy, pleasant-smelling, biologically-active worm bin is the right amount of air and moisture. Remember, the goal is damp but never soggy.

Fluff and stir the bin weekly (or every other week) to break up big clumps and introduce air before adding new food or bedding. Beneficial microbes also enjoy aerobic environments.

If your bin seems soggy and stinky, stir in more shredded newspaper, leaves, cardboard bits, or other fresh brown material throughout the entire bin to help absorb the moisture.

If the bin seems too dry on the other hand, give it a light shower with the hose or watering can – but go easy! Start small, stir, assess, and then water. You can always add more water if needed, but it’s more difficult to dry out an overly wet bin if you overdo it.

Worm bins in the winter

Worms bins need to be protected from freezing, and they also vastly reduce their activity in cold conditions. If temperatures below 32°F are the norm for you during winter, plan accordingly. Can you permanently locate or move your worm bin inside a garage, shed, laundry room, or other spare space to help protect them?

When we lived in an apartment in Providence, Rhode Island (brrrr), our worm farm lived outside our door in a shared uninsulated stairwell. It got *almost* as cold as outside, which was single digits in the winter! We wrapped the bin in a large fleece blanket to help insulate it. Wool blankets would be even better.

You can also help insulate the bin with deep mulch inside the bin, such as a layer of cardboard plus a lot of leaves on top. Ours weren’t all that active in the Rhode Island winters, but they survived. Our new homestead has an occasional hard freeze and we often forget to protect them at all. They’re tough little guys.

Worm bins in the summer

Temperatures over 95F can also kill worms. In the heat of the summer, definitely keep your worms in a shady spot with good airflow. If it’s crazy hot out, can you move the bin inside to a more cool location? Keep your worm bin away from radiant heat sources, like a hot south-facing wall.

If you can’t move your bin to a cooler location, and it’s projected be over 95°F, the following measures can help keep a worm bin cooler:

• Putting ice cubes or blocks of ice on top.
• Place a frozen bottle of water (wrapped in newspaper) down inside the bedding.
• Stir and fluff the bin to release some heat, then place damp sheets of newspaper, cardboard, brown paper bags, or burlap on top to cover the bedding and worms, and leave the lid off a for a little while.

All that said, we kept a worm compost bin for years while we lived in Chico, CA where summer temperatures were regularly over 100°F and occasionally over 110°F! We lost the worms only once in a prolonged heat wave. Other times, some died but some lived, so the population bounced back once the weather improved. Back then, I didn’t do many of the intervention techniques I just described. I was a busy, distracted college student – and the worms did okay. Try not to stress about it too much!

If you’re worried about temperature extremes, keep in mind that worm bins are perfectly fine to keep indoors year-round. An Instagram follower once told me she hid a worm bin under her kitchen sink for over 6 months before her nay-saying husband even noticed. Back in Chico, my environmental studies department had a worm bin right in the office. Worms make very well-behaved office pets!

We have just covered are all the key elements you need to make and maintain a simple worm compost bin! I’m sure you’re curious… what about actually using the compost though?

How to Harvest Worm Castings

Once you’ve had your bin up and running for a few months, you can start harvesting small amounts of finished compost – worm castings! With time, you can gradually harvest more and more as your population grows and they start turning more of the bin over. We add worm castings to every planting hole when transplanting seedlings outside, and the plants love it!

Here is our guide on how to harvest worm castings from a worm farm. In short, we feed the worms on just one side of the bin for several weeks so they will migrate there. Then we can harvest the castings from the opposite side of the bin, getting as few worms as possible. Finally, we sift the castings with a DIY screen to catch any large chunks (or worms) and toss them back into the bin.

Demonstration video: setting up a new worm bin

That is how we vermicompost.

It’s simple, it’s fun, and it’s effective! I hope you find this tutorial to be the same, and feel ready to start your own worm bin at home. Feel free to ask questions in the comments below, and happy composting!

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• How to Make Actively Aerated Compost Tea to Fertilize Your Garden
• How to Build a 3 Bay Compost Bin: Step-by-Step Guide with Photos
• Hugelkultur: A Natural, Cheap Way to Make or Fill Garden Beds
• Companion Planting 101 (w/ Garden Companion Planting Chart)
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How to Make a Worm Compost Bin (Worm Farm)

Vermicomposting, or composting with worms, is easy, fun, and sustainable! Read along to learn how to set up and maintain a simple worm compost bin at home, including tips on how to feed a worm bin.

Active Time30 minutes mins

Keyword: diy worm bin, how to make a worm bin, vermicomposting, worm bin, worm conpost bin, worm farm

Cost: 50

Equipment

• A simple bin with a solid lid, such as a large durable plastic storage tote. 20-50 gallons recommended, durable/heavy duty and not transparent
• Dry bedding material, such as shredded newspaper, coco coir, dry leaves, grass clippings, shredded cardboard, brown paper bags, or straw. enough to fill about the bottom 1/4 of the bin
• Compost worms. I start with 1,000-2,000 worms (one to two pounds) for a 35 gallon worm bin
• Grit or dirt just a few handfuls
• Food or garden scraps
• Recommended: a drill and 1/4" bit to add air holes to the bin

Instructions

Making a New Worm Bin

• Add a couple dozen small air holes to the side walls of the bin near the top. We use a 1/4" drill bit. Do NOT add "drainage" holes to the bottom.
  
• Fill the bottom quarter of the bin with brown/dry bedding material of choice. We like to use a mix of shredded newspaper and coco coir – which comes in brick form and needs to be rehydrated and fluffed first. Use about 5 pounds of coco coir bricks for a 35 gallon bin. (Don't overwet the coir, damp is good – not soggy)
  
• Lightly moisten the bedding in the worm bin. Worms like damp environments, but not sopping wet – they breathe through their skin and can drown! Too wet of a worm bin also makes it stink.
  
• Add compost worms. Dig a hole in the bedding, add the worms, then bury them.
  
• Tip: the worms may try to escape the bin at first. Cover the material in the bin with a layer of damp newspaper or brown paper bags to help keep them in, and check the bin every day or two. Collect worms that have gathered around the lid or walls and put them back inside the bedding.
  
• Add a small amount of food right away. See "yes" and "no" list for food and routine feeding tips below.
  

Feeding a Worm Bin

• Each time you feed the worm bin, dig a small hole and bury the food by at least a couple inches of bedding.
  
• Good food for worm bins include most fruit and vegetable scraps, crushed eggshells, spent coffee grounds, loose leaf tea or paper tea bags (staple removed) and tender garden trimmings. Avoid dairy, meat, processed or moldy/rotten foods, citrus (too acidic) or animal manure, and limit starchy foods, grains or bread.
  
• Under ideal conditions, worms can eat their body weight in a day (so 1 pound of worms can eat 1 pound of food waste). Yet they slow down during cool conditions, so err on the conservative side. We prefer to feed our worm bin weekly. You'll learn with time how much your worms can eat in a week. If you add too much food before they can eat it, it will rot and stink.
  
• Before adding food each week, carefully stir and fluff all of the contents of the worm bin to introduce air, assess how much food they’ve eaten since last week, and generally check the condition of the bin.
  
• In an established worm farm, it is best practice to add a handful of “browns” (bedding) each time you add more food scraps, or at least once every other week.
• Cutting or breaking up large chunks of food will help the worms break it down faster.
• See the full written blogpost for more ongoing maintenance tips, including how to keep your bin the right moisture level, and how to protect it during extreme heat or freezing.

Notes

Note that temperatures below 35F or above 95F (internal bin temperature) can kill compost worms. See the written blogpost for tips on how to keep a worm bin cool or warm. Suggestions include (not limited to): moving it indoors or to a more protected location, keeping it in the shade, wrapping it with wool blankets, using deep mulch inside the bin for insulation, adding frozen water bottles to keep it cool, and more.