Vermicomposting: A Guide to Composting with Worms

If you're like me and you enjoy cooking, you probably end up throwing a lot of food scraps down the garbage disposal or worse, in the trash. This is a very wasteful way of disposing of food and contributes significantly to global warming. Fortunately, you could easily, and with very little time investment, turn food scraps into rich compost that can be used in your vegetable garden, on your potted plants, or given to friends.

If you're a city dweller like me, you're probably wondering how you can manage a compost bin in the heart of the city- but its really quite simple. Compost bins range from very small (can be stored under your kitchen sink or in the closet) to very large (multi-tiered-can be stored on your deck, in the garden or garage). Personally, I keep my multi-tiered worm bin on the fire-escape outside, which doubles as a deck in warm weather.

You're probably reading this article in horror thinking, "Why do I want to keep a bin of decomposing, stinky food in my own apartment?" Actually, worm bins are not supposed to stink, and will not if done properly. As long as you do not overload your worms with too much food, they will manage the waste quite well and your bin will stay in balance. This of course depends on the air circulation in your bin, which is why I recommend purchasing a bin rather than making one at home. A properly managed worm compost bin will smell like rich soil - or humus. If it does stink, you have done something wrong (see my troubleshooting section).

Read this series of articles and you will learn everything you need to know about vermicomposting, or composting with worms, including materials needed, how to manage the bin, troubleshooting techniques, how to harvest the worm castings and worm tea, and how to use it!

Materials Needed:

1) Multi-tier Compost Bin

While you may have heard that you can construct your own compost bin, I would not recommend it. When I first started composting, I used a makeshift container that had been transformed into a compost bin, and this was a disaster (stinky and moldy!). Worms need a great amount of air circulation and protection from the heat of the sun, and home-made bins often do not provide. If you do wish to go the handy-route and build your own, there are other articles online that will show you how, step by step.

Fortunately for a penny pincher like myself, many counties across the United States have programs that offer subsidized compost bins for your home or garden. Bins that normally cost more than $100.00 are being offered for a mere $30-$40. I received a subsidized Smith & Hawken bin from Alameda County, California, and this bin has been fabulous. Do a quick Google search to check your county's waste and composting programs.

2) Earthworms- Red Wigglers (eisenia foetida)

Begin with 1lb of Red Wiggler Earthworms, or even 2lbs if you are a heavy cook, cooking for a family of 4+. Once your bin gets going, 1lb of worms can eat up to 1lb of food waste per day. Your worms will also multiply in the compost bin itself, so you do not need to worry about replenishing them. Worms can be bought in many garden supply stores as well as online. They look long and red, and be thin when you first get them. If you feed them properly, they'll be fat in no time.

3) Bedding- saw dust, shredded newspaper, cardboard, hay, etc.

Bedding is essential to the balance of a compost bin- worms eat their bedding and burrow inside of it for protection. Without bedding, the worm bin will most likely take a turn for the worst- food scraps will begin to mold, worms will get sick and die, and the worm bin will stink and attract flies. Not good! Make sure to add bedding when you set up the bin. You can add bedding as you compost too, especially if the compost bin seems too wet and food is beginning to mold.

4) Water

Earthworms do not have lungs and so they breathe through their skin. That is why worms need water in order to breath-- because worms cannot breathe unless their skin is moist. Thus, water is an essential element of a properly functioning worm bin. Depending on the weather and your usage, add a few cups of water into the bin every week- the bedding should resemble a wrung out sponge. Do not worry about over-watering the bin-if you have added excess water, it will simply drain off and collect as "worm tea" (more on this later) in the bottom tier of your bin. That given, you do not want your worms swimming in water!

4) Food Scraps-

Do not add:

Spicy food

Oily/greasy foods

Onions

Meat or bones

Citrus fruit

Fatty Items

Foods high in protein (beans, tofu)

Dairy

Manure of any sort

Do add:

Coffee Grounds, including filters (they love this)

Egg Shells

Fruit

Vegetables

Melon Rinds, Peels

Worms do not have teeth so they cannot chew their food- they simply eat the fungi that grows on food as it decomposes. To aid in the decomposition of food, it is best if you cut/shred your kitchen scraps before adding them to the bin. When food is added in large chunks (whole fruits, whole vegetables), they tend to mold too quickly for the worms to process.

Worms, like chickens, birds, and turkeys, have a gizzard. As worms eat their food, gritty foods like sand, dirt, and coffee grounds push against each other grind the food in their mouths into small pieces (like a food processor) so that worms can process them. This is why it is important for you to feed your worms coffee grounds and other gritty foods like egg shells, because the grit helps worms process the other food you give them.

**Note** Never add moldy food to your compost bins- mold is toxic to worms and will make them sick, potentially killing them if you do not extract it immediately.

Starting your Worm Bin

After you have all of the supplies enumerated above, you can set up your composting worm bin and begin feeding your worms. Following these steps should lead you to composting success.

1) Location

Set up your bin in an area of your apartment, garden, garage, or deck that stays relatively cool in temperature-it should not be in direct sunlight for more than a few hours per day, nor should be it be in the snow. If your worms do have to stay out in the sun, be sure that the walls of the bin are not clear- the heat penetrates the bin and fry the worms. If you live in an area of world where it freezes, either bring your worm bin inside during the freezing months or add a blanket or two on top of the worm bin to keep it warm. If you have a garden, you can bury the bottom half of your worm bin into the soil of your garden, and this will keep it from freezing.

2) Add Bedding & Worms

While some compost bins come with a block of bedding, others do not so you will have to make do. Shred newspaper, cardboard, or other materials listed above and let them soak in a bucket of water overnight. Once the bedding is ready the next day, add the bedding to your worm bin, and add the worms. They will quickly borrow inside of the bedding, which has become their new home.

3) Feed the Worms

As you prepare dinner each night, try to remember not to throw away the ends of tomatoes, the tops of carrots, the peels from fruit, etc. and instead chop them up into small inch pieces and save them in a small container in or near your kitchen. You can use this container to save food in for a few days. Once you have gathered a good amount of chopped scraps, you can begin feeding your worms. Some people prefer to freeze fruit peels to keep fruit flies from investing the worm bin. Others like to puree all food scraps before adding them to the bin to aid decomposition.

Begin by adding food slowly to your compost bin. The worms will take a few weeks to get settled into their new home and will not eat as much food as they are capable of. Adding food slowly will allow the worms to acclimatize to their surroundings without bombarding them too much. If you add too much food too quickly to your bin, the food will mold, thus potentially killing your worms.

Increasingly add more food to your compost and determine for yourself how much they can handle. You will figure out how to keep a balance in your worm bin, as each bin is different.

4) Add Water & Rotate the Compost Bin

As I said above, add a few cups of water to your worm bin every week. You want to keep the bedding moist without drowning the worms. This requires a balance and you will figure it out as you go along.

While some compost bins are built to be rotated, others, like mine, are not. Simply take a pitch-fork like tool to rotate the contents of the bin, taking care not to stab the worms. This usually requires a gentle stir and not anything much more aggressive than that. Do this when you add the food every few days.

5) Collecting Worm Tea

Worm tea is the liquid that will collect in the bottom bin of your multi-tiered worm bin. This is runoff of the water that has been filtered through the compost/humus your worms are producing. It is sort of like worm pee, if you like, and is amazing fertilizer. The tea will collect in the bottom bin and you can later use it as liquid fertilizer. More on this later.

Troubleshooting your Worm Bin

These are the most common problems facing your worm bin. You may see them from time to time until you figure out how to prevent them and keep your bin in balance.

Fruit Flies- While fruit flies do not hurt the worms or the functioning of the bin, they are annoying and pesky. Try burying the food underneath the bedding to avoid flies. Also adding Dolomite/Lime to the bin can help- but take care not to let the substance directly touch the worms because it can harm their bodies. Lastly, if they bother you, stop adding fruit to the bin because this attracts flies. Try freezing the fruit peels before adding them to the bin- this could stop the fly problem.

Mold - Extract the moldy chunks immediately. Cut up the food scraps into smaller pieces-you can even puree them in a food processer or blender if you like-before adding it to the bin. If this doesn't work, stop feeding your worms for a week or so and then add food slowly. Increase air circulation. When you add the food, try burying it under bedding to prevent molding.

Odor - Stop adding food for a few weeks and let the bin normalize again. Your bin may lack circulation so try fluffing up the bedding to allow air to circulate through. Add dry bedding to the bin and stir the food inside of the bin to also allow circulation.

Worms are dying or leaving - You may not notice that worms are dying because they decompose into the compost bin. Try to monitor the amount of worms and you will notice if it is getting smaller. You may be adding too much water or too little, and this could drown the worms or suffocate them. Make sure the worms are getting enough to eat and the food is not moldy. If you do not have a tiered worm bin, the worms may end up eating their own castings and this is deadly to them. Its time to harvest. If worms are leaving in large numbers, conditions are not good for them. You may be drowning them or not adding enough food.

Usually, aerating your bin will solve many problems. Be sure that the bedding is not stopping air circulation-this is why stirring your bin is important.

Harvesting your Bin

If you have a multi-tiered bin, harvesting is super easy. By the time you have started feeding your worms on the top-most level of your bin, the second bottom-most (above the worm tea bin) is likely ready for harvesting. This can take from 2-6 months. Take out this bin and it should look like rich dark brown soil or humus. There may be a few peels that did not decompose in the bin and you can pick these out. Likewise, if there are any worm stragglers you can pick these out and add them to other bin tiers.

Simply empty the bin of its contents and add this rich fertilizer to your plants. Its really that simple. Now, if you do not have a multi-tiered compost bin, you will need to try some other complicated methods of harvesting. There are many resources online that will instruct you how to do this.

Worm Tea

Worm tea is the liquid fertilizer that has gathered at the bottom-most tier. You may need to empty this periodically into containers because it tends to fill up quickly, especially if you have added a lot of water to your bin. Drain the tea into containers, and these containers can keep for a few weeks. DO NOT add the tea straight to your plants-it is so strong that it might kill them. Dilute the tea, 8 parts water, 1 part worm tea, into a watering can and then add it to your plants just like any liquid fertilizer.

The benefits of worm tea and compost is infinite, and you will see the results directly. There will be no need to buy fertilizer or compost anymore from your garden supply store- this home-made fertilizer is healthier, non-polluting, and cheap to make. Plus think of all the food waste you are NOT adding to a garbage heap, and instead infusing back into the soil. It's a wonderful cycle of life.