A Beginner’s Guide to Worm Composting Inside Your Apartment

A Beginner’s Guide to Worm Composting Inside Your Apartment

Live in an apartment and want to compost?

Then it’s time to buy some worms.

After doing a ton of research, here is why I believe vermicomposting – having worms eat your garbage to produce nutrient rich fertilizer – is the best composting method for those living in apartments:

  • Most cities don’t have composting systems, so individual composting is the only choice
  • Most apartments don’t have yard space to compost outside so you need an indoor composting method. This rules out outdoor composting systems as well as anaerobic composting methods like Bokashi buckets which require you to bury your food waste
  • Designed and maintained correctly, worm bins don’t smell nor attract pests

The benefits?

  • You close the loop on your food waste. In Ho Chi Minh city alone, food waste accounts for more than 60 percent of the city’s 8,300 tons of solid waste per day
  • Composting reminds you everyday that there is no waste in nature, a paradigm shifting experience
  • You produce the most nutrient rich compost in the world. Worm castings are nicknamed “black gold” because they stimulate plant growth more than any other natural fertilizer. One tablespoon of worm castings provides enough organic nutrients to feed a 6 inch potted plant for 2 months

Prior to building my first worm bin, I had ZERO experience with composting. I borrowed armfuls of composting books from the library; watched hours of YouTubers building worm bins; read through dozens of Amazon reviews on commercial worm bins; and even visited a worm farmer in Saigon. In sum, I obsessed over worms and personal compost systems for a month. Not many have that luxury! So I hope this beginner’s guide gets you up to speed and composting asap.

I have to give a shout out to Mary Appelhof, a true hero. She spent her life tirelessly championing worm composting, and most of the tips in this guide come from her bible on vermicomposting, Worms Eat My Garbage, which has sold over 200,000 copies. It’s the most useful book I’ve found on worm composting with its clear directions and time-tested formulas.

I also think watching YouTube videos, especially this Beginning Worm Bin series by Down to the Roots, is the best way to preview the experience of making and maintaining a worm bin. While most of us won’t have such an elaborate set up, I found his detailed explanation of the process to be invaluable – thank you Down to the Roots, if you ever see this!

Alright, here we go! This is the guidance I wish I had when I started:

Step 1: Measure Your Food Waste & Apartment Space

Instead of rushing to Home Depot to buy two giant rubber bins (like most DIY worm bins online), I should have weighed my weekly food waste first. Why?

Your amount of food waste determines the size worm bin you need. Most of us apartment dwellers don’t have much extra space. So this could save you from buying a huge bin – and space sucker – that you don’t need.

Weigh Your Food Waste

Weigh your organic garbage for at least 1 week. Two weeks is probably ideal to get a more accurate measurement.

I weighed my food waste with a portable luggage scale.

You need 1 square foot of bin surface area per 0.5kg of weekly food waste. So given that I waste 1-1.5kg of food per week, I need a bin that is 2-3 square feet.

For those not good at math, two square feet could be 2 feet long by 1 foot wide. Three square feet could be 3 feet long by 1 foot wide OR a bin 2 feet long by 1.5 feet wide.

What about depth? Redworms nibble their way up to the surface, so your bin should be relatively shallow, 1 to 1.5 feet deep. If your bin is a little taller, no worries. However, taller bins could cause your bedding to compress and push out air, leading to anaerobic (i.e. smelly) composting. Plus, a taller bin takes up more space.

Given bins of different shape but equal volume, choose the bin with maximal surface area. Doing so allows more air to reach the worms and worm bedding, and gives more surface area on which to place waste. So a shallow square or rectangular container is preferable to a deep circular bucket.

What Size Worm Bin? 

You need 1 square foot per 0.5kg of weekly food waste.

What’s your weekly food waste?          kg

Divide by 0.5  =          square feet

Example: My weekly food waste weights 1.5kg, so I need a 3 square foot worm bin (1.5/0.5 =  3).  Worm bins should be 1-1.5 feet tall.

Where to Put Your Worm Bin?

Now that you know how big of a bin you need, think about where you could put your worm bin. 

Worms do their best work between 15-25ºC (59-77ºF), so you want to keep them in a relatively cool place. Worms hate light, so you want to keep them in a dark colored bin and in a relatively dark space. That’s why closets and under the kitchen sink are two popular locations for worm bins.

You’ll also need a second bin to collect worm pee and excess liquids, so that will add 6-9 inches of height to your bin (I use 4 beer cans to prop by first bin up). Where do you have enough space for your bin? Most people prefer to keep their bins – and worms – out of sight, but a visible worm bin is a great conversation piece:

Friend: “What’s that?”

Me: “That’s where I keep thousands of pet worms.”

I live in a relatively small apartment in Saigon (50 square meters). The only place I could put my worm bin is under the sink in my bathroom. The other areas of my apartment, including the kitchen, are just too hot and bright, and my closets aren’t big enough to fit the worm bin I need. The average temperature in Saigon is 28ºC so I have to find the coolest space in my apartment.

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Step 2: Build Your Worm Bin

You’ll need to buy two bins for your first worm habitat. The first bin will be where the worms live, and the second bin will be placed under the first bin, to collect excess liquid from the first bin. Some put a tray underneath the main bin, but I don’t like the idea of guests seeing unidentifiable liquids in my bathroom, so I am using the two bin method.

Unlike in the US, large, dark rubber bins are not readily available in Ho Chi Minh. Duy Tan seems to be the largest producer of plastic bins, but their bins are clear and bright – not ideal for worms. I ended up spending extra money on these 2 bins from Lock & Lock (23.6″ x 15.6″ x 14″) for 388,000K VND each. I will gift these worm bins if I move, so I see it as an investment for at least 2 (and hopefully dozens!) of worm composters in Saigon.   

How to Build Your Bin

Bottom: Drill 1/8 or 1/4 inch size holes on the bottom of bin. Most bins have a slightly depressed perimeter – this is where you want to drill to let any excess liquid escape. This will prevent a flooded worm bin. I drilled about 20 holes, 3-4 inches apart.

Sides: Drill 1/4 inch size holes around the top perimeter of the bin, every 3-4 inches. I drilled 6 holes on the long sides and 3 holes on the short sides. This is to ensure ventilation for your worms and their aerobic composting process. 

Top: Drill 1/4 inch or larger size holes on the lid, every 3-4 inches, to allow plenty of ventilation for the worms.

The number of holes is not really important as long as the bin is well ventilated and drains.

I prefer to keep my holes on the smaller side (1/8 – 1/4 inch) so I don’t have to install mesh screening to keep out other creatures. So far this has worked fine.

You can use the inside of toilet paper rolls, beer cans, or bricks to stack your worm bin inside the secondary bin. The side ventilation holes of the worm bin should not be covered by the liquid collecting bin.

My apartment maintenance guy had a power drill, so I got him to help me.

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Step 3: Prepare Your Worm Bedding

What Makes the Best Worm Bedding?

Let’s take a second to talk about what your worms need to thrive.

Mary Appelhof outlines four critical factors:

  1. Temperature: Redworms eat the most and convert waste best at temperatures between 15-25ºC (60-77ºF). They can survive between 0-35ºC (32-95ºF). Below 10ºC (50ºF) the worms reduce their feeding and above 35ºC (95ºF) worms can suffer as increased microbial activity consumes their oxygen.
  2. Moisture: Redworms need moisture as they breathe through their skin, which must be moist for the exchange of air and their excretions to take place. Too much moisture can  “drown” your worms. Many experts advise that your bedding should feel like a wrung out sponge. I found that to be a good rule of thumb.
  3. Acidity: ph 5-9 is most suitable for redworms (pH 1 being most acidic, pH 14 being most alkaline). Worms prefer a slightly acidic environment. Providing too much acidic food – like orange peels – would be like pouring vinegar into the worm bin. You can use a soil pH meter to test the acidity of your worm bin in 3 different locations. If the worm bin smells bad, you probably have a moisture or acidity problem.
  4. Ventilation: vermicomposting is an aerobic process. Worms use oxygen in their bodily processes, so it’s important that you allow air to circulate around your container. Plus the ventilation will keep your bin odor free.

This means that you need worm bedding materials that hold moisture but are light and fluffy. Black and white newspaper, cardboard, and coconut fiber (coir) are readily available in Ho Chi Minh, so that’s what I used. You can also use leaves, animal manure and peat moss which are natural habitats for redworms, but these were harder to collect. I also didn’t want to bring more poop into my apartment. 🙂

At first this moisture level can be tough to gauge, but you’ll get a feel for it. 

Shredded newspaper is the cheapest and most available bedding. My neighbors give me their old newspapers for free. If you have a paper shredder, great! Otherwise you can tear your newspaper into 1″ x 1″ strips. Newspaper ink is not harmful to worms, as the basic ingredients are carbon black and oils. Colored inks, however, may be a problem, so try to avoid colored newspapers.

How Much Bedding?

You need 0.18kg per gallon OR 3lbs per cubic foot

How many gallons is your bin?        gallons

Multiply by 0.18 =       kg bedding

Example 1: My bin is 22.3 gallons. So I need 22.3 x 0.18 = 4kg of bedding

Example 2: My bin is 2 feet x 1.3 feet x 1.16 feet = 3 cubic feet. So I need 3 x 3 cubic feet = 9lbs of bedding = 4kg of bedding

An easy rule of thumb is to fill your bin 75% full with bedding.

Wetting Your Bed

In a plastic bin, your water to bedding ratio should be 2:1

How much bedding do you need?        kg

Multiply by 2 =        kg water to moisten your bedding

Example: My plastic bin needs 4kg of bedding, so I need 2 x 4kg = 8kg of water to get the right moisture level

Assuming you’re using a plastic bin (which holds moisture better than wooden bins), you can place your shredded newspaper into water twice its weight. You can also just soak your newspaper bedding in the sink for a few hours, and then wring dry them out. The bedding should be damp like clothes out of a washer.

Some vermicomposters leave their worm bedding water out for a few days to let the chlorine evaporate. I didn’t do this and my worms seemed to be okay.

I cut up cardboard for my first bin – not an easy task – but the worms loved it. I would soak my cardboard in water for a few minutes, then wring it out. For my second bin in Ho Chi Minh, I am experimenting with a cardboard less bin.

Coconut fiber is clean, odorless, retains moisture well, and is less acidic than peat moss, another common worm bedding material. It’s available for cheap in Vietnam.

Leaves are worms’ natural habitat, so could make excellent worm bedding. In Ho Chi Minh, I’m not sure what chemicals are used to grow trees and plants here so I avoid using roadside leaves.

After filling your worm bin with bedding, add a handful or two of soil which provides grit for worms and soil bacterias that will aid the composting process. You can also add your first food scraps to introduce more beneficial bacteria to the bin. Mix all your bedding elements together. Does it look and feel like something worms would enjoy crawling through? Imagine shaded, damp, crumbly soil on a forest floor… 

Down to the Roots recommends aging your bedding for 1-2 weeks before your worms arrive, as worms need beneficial bacteria to help them break down food. While not necessary, I think this is a good idea. A more natural, less sterile habitat will ease your worms transition to their new home.

Remember, the ideal worm bedding is light and fluffy, allowing air flow throughout the container, yet moist enough for your worms to breathe comfortably.

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Step 4: Order Red Wiggler Worms

In the US, I ordered 1,000 worms from Uncle Jim’s Worm Farm. Amazingly, they came in a small mesh bag filled with peat moss. Redworms are sturdy creatures!

Worm growers commonly estimate that there are about 1,000 worms per pound or 2,200 worms per kilogram. Regardless, it’s the weight of worms, not their number, that is important in vermicomposting. So don’t worry about counting your worms. 

How Many Worms?

Worms can eat half their weight every day, so your worm to waste ratio is 2:1

Worm to Waste Ratio = 2 to 1

What’s your weekly food waste?        kg 

Divide by 7 =        kg food waste/day

Multiply by 2 =        kg worms you need

Example: My weekly food waste is 1.5kg/week. Divided by 7, I waste 0.21 kg food waste/day. So if I multiply 0.21 by 2, I need  0.42 kg worms to get started. 

Assuming 1 kg of worms = 2,200 worms, then I need about 0.4kg = 880 worms to eat my garbage. I’ll round that up to 1,000 worms.  

In Ho Chi Minh, Vietnam, I ordered my worms from AnPhu Earthworm Company. I recommend that you get in touch with them through their WhatsApp number. 500 worms came in a 10kg bag of cow dung and compost. This cost 250K VND + 30K VND for delivery. 

I was a bit nervous – and grossed out! – about having 10kg of cow dung inside my apartment. My contact at AnPhu Earthworm told me that the worms will eat through the cow dung in 1 week, and that I should cover 2/3 of the bin with newspaper (instead of a lid, which will block airflow). I shouldn’t feed the worms any food waste for a week – just leave the worms in their cow dung and compost bedding.

I was paranoid about the slight smell and attracting flies so I compromised by adding shredded newspaper on top and covering the bin 80%. The worms seem to be doing fine so far!  You can see my roller coaster of emotions installing the bin here :).

In addition to speaking with your worm supplier, I also recommend getting help on the Red Worm Composting Facebook group, which has over 15,000 members. I posted my situation there and got a ton of helpful responses. 

 
AnPhu Earthworms come in 10kg bag...
...of cow dung and compost mix
I covered with shredded newspaper to give plenty of air...
...but didn't like the smell so keep lid 80% on

Which Composting Worms Should I Order?

I recommend Redworms, or Eisenia Fetida, that live and feed in surface mulch areas on decaying matter like leaves, manure or compost piles. These worms are also popularly known as Red Wigglers. 

Why redworms?

  • Redworms can eat and digest large amounts of organic material quickly
  • Redworms can tolerate a wide range of temperatures, acidity and moisture conditions
  • Redworms are tough and withstand handling well
  • Redworms are fast reproducers but will not over-populate
  • Redworms make great bait for fish or reptiles 
  • Redworms are the most available worms on the market

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7 Interesting Facts about Redworms

  1. Redworms have no eyes and cannot see but are sensitive to light
  2. Redworms don’t have teeth or a stomach, but rather a gizzard which helps break down food
  3. Redworms have 5 pairs of aortic arches that function like a heart
  4. Redworms can regenerate their heads or tails
  5. Redworms have both male and female organs, yet most need a mate to reproduce
  6. Redworms can double their population in 90 days
  7. Redworms will naturally lay less eggs as their population becomes too dense in one area

Step 5: Introduce Worms to their New Home

I’ll trust the worm farmers on this one. According to Uncle Jim, worms should be introduced to their new environment as soon as possible. Place them in the center of your compost bin, sprinkle with water and cover them with moist newspaper. Uncle Jim also recommends placing a light directly over the open bin for the first two hours, which will accelerate the adapting period. 

I remember getting my first bag of worms. I was so excited. Would they still be alive after being shipped across the United States? Would they slither out in a mad rush to escape?

I was pretty grossed out the first time I saw them. You may have the same reaction! Don’t worry. Soon you’ll get used to living with them and feeding them. They become like any other pet. You may even talk to them and coach them like me. 😉

I recommend shining a light into the bin for at least 1 day. This will force the worms to burrow into their new bedding and get used to their new habitat. I didn’t do this and was stunned to see an army of worms crawling up the bin trying to escape! Mutiny! This could also have been because I had just prepared their bedding, which was quite sterile. I only had this problem the first day. And don’t worry, red wigglers are quite sturdy creatures. You won’t burn or harm them with the light.

Again, remember what worms need to thrive: moisture, ventilation, and the right acidity and temperature. Your bedding should be moist like a wringed out sponge. Think damp, not soggy. Your worm bin will already be properly ventilated, so no worries there. And ideally the bin is in a relatively cool place (15-25ºC).

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Step 6: Feed Your Worms

Now it’s time to get your hands even more dirty! 

This is a fun step that requires some experimentation.

What to Feed Your Worms

In short, feed your worms organic food waste, egg shells, and coffee grinds. Don’t feed them meat, dairy and oily foods, which become rancid when they decompose and tend to attract pests, or too much citrus, which will make your worm bin too acidic.

What Goes In

  • Vegetables (bok choy, broccoli, lettuce, onion skins)
  • Fruits (apple cores, banana peels, mango skins) 
  • Carbohydrates and Grains (bread, rice, pasta, pizza crust)
  • Eggshells (washed out)
  • Coffee grinds and Filters
  • Tea Leaves and Bags

Pulverized eggshells and coffee grinds are particularly helpful, as they provide grit for worms to process food.

What Stays Out

  • Meat, dairy, and oily food, which become rancid as they decompose
  • Citrus peels, pulp or juice, pineapples, or too many tomatoes, which are too acidic
  • Super salty foods like olives (or use, but rinse first)
  • Waxed cardboard
  • Plastic or Wax Coated coffee cups
  • Produce stickers
  • Plastic, Styrofoam
  • Glass, Metal, Rubber (hope these are obvious!)
  • Pet waste or human waste 
  • Diapers

While some compost meat and dairy waste, I don’t want to risk of foul odors or attracting pests to my apartment.

Prepping Your Worm Food

Worms can eat ground food waste more readily than large particles of food, as a worm’s mouth is tiny and toothless. Does this mean that you need to blend your food waste like some worm owners? No. It really depends on how much time and energy you have. The goal of many vermicomposters is to save energy on waste management, so grinding food waste is inconsistent with why they want to compost. Any organic food waste will eventually break down anyways.

I cut my food waste (usually fruit peels and stalks) into more manageable chunks for the worms. But even this is unnecessary. It’s more important to have a worm bin then to have perfect worm food – so if you don’t like touching your trash, don’t stress about this!

I keep my food waste in the freezer to aid the decomposition process and keep my garbage away from fruit flies. 

note: after doing this for a month, I became much more comfortable handling trash, as we all should be. There is no waste in nature. As Thich Nhat Hanh so eloquently says: “A rose can’t exist without trash, and trash can’t exist without the rose.” A big reason I compost is to (literally) feel this connection to nature, which is hard to do in big cities.

How to Feed Your Red Wigglers

Worms eat roughly half their weight per day. Thankfully, we’ve already done the calculations, so you just need to bury your food waste into the bin once or twice a week. If you have more food waste than usual you can store in your freezer, which will help aid the decomposition process.

Imagine your worm bin divided into 6 parts. I bury my scraps twice a week in the same spot, so 5 weeks will pass before I dip into a region already containing food waste. I put a twig above my last feeding location and work clockwise around the bin. You can also draw a grid on top of your bin so you remember where you last put food.

Each time I deposit food, I add some bedding under the food to absorb its moisture. I then cover the newly deposited waste with 2 inches of bedding. This makes food waste less accessible to flies, and the bedding adds more carbon sources for the worms. Some worm owners wrap food waste in a newspaper to get the same effect.

I then cover the bedding with a moist newspaper to keep moisture in the bin. 

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What’s the Optimal Carbon to Nitrogen Ratio for Composting?

Scientists have determined that the fastest way to produce fertile compost is to maintain a Carbon:Nitrogen ratio between 25 to 30 parts carbon to 1 part nitrogen, or 25-30:1.

If the C:N ratio is too high (excess carbon), decomposition slows down. If the C:N ratio is too low (excess nitrogen) you will end up with a wet, stinky pile.

Note: this is by material composition, NOT weight. So please DON’T throw in 25kg of bedding for every 1kg of food waste.

Estimated Carbon to Nitrogen Ratios

Common Worm Bed Materials, typically made of “browns” (C:N ration higher than 30:1), which are high in carbon

  • Cardboard, shredded 350:1
  • Newspaper, shredded 175:1
  • Leaves 60:1
  • Straw 75:1
  • Wood chips 400:1
  • Fruit waste 35:1

Common Worm Foods, typically made of “greens” (C:N ratio lower than 30:1), which are high in nitrogen

  • Coffee grounds 20:1
  • Vegetable scraps 25:1
  • Table/kitchen scraps 15:1
  • Cattle Manure 15:1
  • Grass clippings 20:1

So depending on the weight and C:N ratio of your materials, you might consider throwing in 2 parts “green” (higher nitrogen) to every 1 part “brown” (higher carbon) for optimal compost speed. 

Since my food waste is much heavier than my newspaper bedding, I find one handful of food waste: one handful of newspaper to be good ratio.

The important thing here is to monitor the moisture level of your bin. The moisture level should be like that of a wrung out sponge. If the bin starts to get smelly or too moist, add more browns.

Step 7: Keep Your Worms Happy… and Your Bin Odor Free

I remember my anxiety feeding my worms for the first time. Did I give them too much food? Too little? Would they like the banana peels or bok choy? How would they deal with egg shells and tea bags?

I would check daily, sometimes every couple hours.

After 1 month of experimenting, I found that it’s best to bury your waste and leave your worm bin alone.

Here are my 3 tests for maintaining your bin:

  1. Feel test: your bedding should feel like wrung out sponge. If it’s too wet, add more bedding. Also if your bedding or compost is hot, you need to give the bin more air.
  2. Smell test: your bin should smell like fresh earth. If not, it’s probably because you’re using too much food or not burying your food. You can also try chopping up your waste to make it easier for your worms to eat. It could also be a certain food stinking up your bin. Meat and dairy are obvious culprits, but I’ve also heard excessive banana peels and cruciferous vegetables (broccoli, cauliflower) can be a problem. Fingers crossed, I have yet to have a smell problem.
  3. Eye test: this one is simple. Are your worms in their beds? Or are they climbing away from the food and bedding? If it’s the latter, it could be a temperature, acidity or moisture issue. Basically they are going to move to where they are most comfortable so adjust accordingly. 

If you’ve followed along so far, you have the right amount of worms, bedding and food in your bin. So you’ll just need to make minor adjustments.

If you want to be more scientific, you can use a portable luggage scale to weigh your deposited food waste and bedding, and a soil pH meter to ensure your bin is the right acidity level.

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Step 8: Harvest Compost

How to Harvest Your Worm Compost

I will post a video as soon as I harvest for the first time in Ho Chi Minh.

It seems there are 2 ways to harvest your vermicompost:

  1. Load your food on one side of the bin, wait a week, then collect the worm-free compost. Afterwards, restart the composting process on the empty side.
  2. Form piles of compost and shine a bright light on them so the worms burrow down, then scoop worm-free compost off the tops.

Using Your Worm Compost

I plan to use my worm compost to feed my houseplants, and herbs and vegetables growing on my balcony.

Here are some other ways you can use your worm compost:

  • Give it to neighbors for their houseplants or gardens
  • Add a worm compost to the bottom of a planting hole when you are transplanting plants or planting seeds
  • Seep your vermicompost in a bucket of water (like a tea bag) to make worm tea to feed your plants

How else do you use your worm compost? Please let me know in the comments below.

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Bonus: Join Elite Company

Smile, you’re not only saving limited landfill space, but also keeping your food from producing methane, a greenhouse gas 25 times more potent than carbon dioxide. 

In fact, if global food waste could be represented as its own country, it would be the third largest greenhouse gas emitter, behind China and the U.S.

If you waste 1.5kg/week like me, you’re saving almost 80kg (175lbs) of organic garbage every year, not to mention all the energy required to transport your waste to a landfill.

Your worms are turning your waste into “black gold” – nature’s finest organic soil to grow your own herbs, vegetables and houseplants. No need to lug those big bags of compost back to your apartment.

Plus you’re utilizing otherwise discarded carbon materials like newspaper, cardboard and coconut husks.

Maybe you’ve even inspired a friend to start her own worm bin.

Just imagine if everyone in your apartment, district or city composted their food waste!

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