Worm Composts
Back in 2012 I found myself thinking about what happened to all the things I threw away.
It didn't sit well with me to think about it all in a landfill rotting away with a bunch of other garbage that would take many years to decompose (if ever). I didn't have a garden at the time, but I had heard about worm composting as a way to turn food scraps into fertile soil rather than adding it to the landfill. I figured making soil that I didn't need (and just adding it to my landlord's planters) was better than creating more waste.
Once the seed was planted I also started paying more attention to what products I bought - what kind of packaging did they come in? Was it recyclable? Was it biodegradable? Was it compostable? I started buying different products, driven in large part by how environmentally friendly their packaging was. Within the first few months of composting and changing the products I bought, I found myself producing one small grocery bag full (3 gal) of garbage once a month. Prior to that I was filling up a tall kitchen garbage bag (13 gal) every 2 weeks. Crunching the numbers, this means I reduced the amount of trash I produced a week by 88%. The benefit of producing less garbage was enough for me to keep up with the worm compost, but I eventually moved somewhere I could have a garden too - so I expanded my operation. :)
There are a lot of different ways to set up a worm compost at home. I have two different homemade worm composts at my house. The first I constructed out of two Rubbermaid bins, which I figured out how to do by watching a video on YouTube a few years ago (there are tons of videos on there now!). It was really simple and only required me to have two bins and a drill to get started. I kept this compost bin inside my small apartment for a while and eventually found a nice shady spot for it outside. The second is even simpler and came about because I was ready to create more compost to use in a garden at my new place and I wanted to have something that looked more organic. Also, my first compost followed all the rules, including the types of food that the worms would like to eat. That meant that the worms in the Rubbermaid bins were never exposed to citrus, onions, garlic, hot peppers, and other strong foods that they typically do not like as much or breakdown as well. The second compost was partly an experiment to see if I could compost without worms and put all my organic food scraps in there, without worrying about the worm's diet.
I don't think the worm-free part of that compost lasted for very long. At some point I thought, "this stuff will decompose way faster if I just put a handful of worms in there.." So, I took a scoop of the original compost, worms included, and added it to the second compost. I continued to put all kinds of food in the second compost, not sure how things would go since the worms might not like it. Low and behold, the worms ate everything. Some foods faster than others, but all of it processed and transformed from food scraps into fertile worm castings (i.e. worm poop). Not only that, the worms were so happy in the new space that they multiplied... a lot... very quickly. There must be 10's of thousands of worms in that second compost now.
The second compost didn't have to be constructed at all. I went to a nearby garden center and bought a half wine barrel. They sell them as planters or as a decorative piece to store your hose or garden tools in. In order to make sure the compost could last inside the wooden barrel, I lined the barrel with black plastic and punched a couple drainage holes in the bottom. I left some of the black plastic loose at the top so I could cover up the compost with the extra plastic whenever I wasn't feeding it, mixing it, or taking some out for the garden. This compost is incredibly healthy now and is the main source of new soil for the garden. The Rubbermaid bin compost is still going strong too, but I still control what foods go into that one and those worms don't break things down as quickly.
There are a lot of ways to make a worm compost and you can get very creative with it if you want. Here's is a quick tutorial on how to make the Rubbermaid bin compost.
HOW TO MAKE A RUBBERMAID BIN WORM COMPOST
Buy two Rubbermaid bins that fit inside each other, but do not nest completely (you'll need a inch or two of space in the bottom bin for liquid to drain into).
You'll only need one lid.
Do nothing to the bottom bin.
Drill small holes (smaller than the diameter of the average worm, but big enough for liquid to pass through - see pictures below to get an idea) along the bottom of the top bin for drainage.
Drill slightly larger holes along the top edge of the top bin (as shown below) for the part that sticks out above the bottom bin for air circulation.
Drill the same size holes into the lid for air circulation.
Put the top bin inside the bottom bin, add worm bedding, some soil, misted water, and worms. Then add in some food scraps and make sure they are buried under the bedding and soil. The "Worm Compost Basics" below provide more details on this stuff.
Put the lid on the bin to keep the light out.
Place Rubbermaid bin in a shaded area or keep it inside and feed the worms periodically.
You now have a Rubbermaid bin worm compost!
Whichever type you choose, there are some basic compost principles that you'll need to follow. These hold true for all worm composts.
WORM COMPOST BASICS
The Worms - Red wiggler worms. They are awesome and not gross - it might take a little time for you to feel that way, but as you go you'll see that they are not so scary after all. In fact, they are really cool. Each worm has 5 hearts! You can check out more cool worm facts here. If you know someone with a compost, you can get a handful of worms from them to get started. If not, you can usually find worms in any local garden supply store and they can be ordered online.
Worm Bedding - When you first get started, it's good to start with some worm bedding in the bin. Worm bedding can be torn up brown paper bags, shredded non-glossy newspaper, or pieces of corrugated cardboard. I started with left over paper from the bakery stand at the farmer's market that otherwise got thrown away. It's good to mix those things together to give them some variety. Add a little potting soil (a few handfuls) into the bedding and then add some water to create the right moisture balance. As you add new food, you can cover the food with new bedding, moisten the bedding, and then close things up for the worms to do their thing. Over time I stopped adding bedding and instead just add potting soil for moisture balancing and covering up the new food instead. When you have enough worm castings in there you will likely find that you don’t need to add anything to it - you can simply cover up the food with the worm castings that are already in there.
Temperature - When the worms are warm, they will break things down a lot faster. When they are cold they slow down and start to go dormant. When you buy the worms from the store many times they just came out of a refrigerator and aren't moving at all. As soon as they warm up they start to wiggle around. The ideal temperature for the worms is 77 degrees F, but they will still eat and be happy between 65 F - 87 F. Just find a shady spot that doesn't get direct sunlight throughout the day for your worms. You can even keep them inside - that's how I started my Rubbermaid bin compost.
Moisture - You'll want to keep your compost moist but not wet. When the compost is too wet, you'll know because the worms will try to escape! If it's too dry it probably means that you don't have enough food in there for them to break down. The more food you put into the compost, the more moist it will be. Worms breathe through their skin and they actually get their oxygen through moisture. If the compost is too dry they can die from suffocation! You can always use a spray bottle to add some water to help balance things if it looks dry. If you have a little excess liquid from the compost, you may want to figure out a way to capture it. You can use it as a boost for the health of your house plants or outside plants. If you use the Rubbermaid bin compost, it will capture the excess fluid in the bottom bin so you can check for that and use it as it's available. If you have this excess fluid you will need to dilute and aerate it before adding it to your plants or soil. In California it's pretty dry, so I don't typically see any excess liquid in the bottom of mine. One other note about moisture, if you are in a place where it rains a lot, the wine barrel idea will be tough to keep up with. Every time it rains you'll have to make sure your worms aren't too wet in there. That could easily be remedied by having a better lid (besides just the black plastic covering I've had on mine). If they do get too wet, just add some potting soil or shredded paper/worm bedding materials and mix it in to help balance it out.
Light - Worms are not a fan of sunlight or artificial light. In fact, 3 minutes in direct sunlight could kill them! Make sure you keep your compost in a shaded place in a container that is opaque and a cover that light can't get through. Light can be used to help get the worms out of the compost when you are ready to use it. If you take a scoopful of compost out and form it into a pyramid or cone shape in the sunlight, the worms will dig themselves deeper into the pile to get away from the light. Then you can scoop some compost off the top once the worms have left. I only tried this once and I didn't like it because it felt mean to expose the worms to light on purpose. I typically just bring the worms with the compost when I use it in the garden - the worms are great for your garden too - so I don't worry about separating them out.
Air Circulation - For the Rubbermaid bin, drilling small holes in the top of the bin can provide enough air circulation for the worms (along the top edge and in the lid). You want holes that are good for circulation, but not super inviting to visiting insects. If you are using another approach, like the wine barrel, there is enough air flow even while covering up the compost with the black plastic. For any container that doesn't fully seal, you should be fine without drilling holes. Air circulation is important not just for the worms, but for the health of the compost itself. If there isn't enough airflow you will notice it start to get smelly. That indicates that there is an anaerobic process happening as the food is breaking down (anaerobic means 'without air'). Anaerobic bacteria is not the best for your compost and garden. A balanced compost with sufficient airflow will smell like fresh earth and not be stinky.
Worm Food - The worms will eat pretty much any fresh fruit and vegetable scraps from your kitchen. Do not add any animal meat or dairy products to your worm bin (with one exception). The only animal product that I add is ground up eggshells, which you can add periodically. You can also add coffee grounds sparingly, it will make the compost more acidic, so it just depends on what you are going for. The worms are usually cool with this as long as you add them gradually (start with one pot worth of ground beans per week and see how they do). They really like pureed pumpkin and watermelon, but so do other bugs! So when do you add things, be mindful of how much you add and make sure it's not too much for your worms. Excessive melon can lead to lots of visiting mites. Banana peels are great for your worms. If you are noticing a fly problem after adding banana peels, considering freezing the peels first and then defrosting and adding it to the bin. Fruit flies tend to lay their eggs on the banana peels and freezing them before adding them to the bin kills the eggs. Worms tend not to like onion, garlic, citrus and other strong foods. However, the worms in the wine barrel don't have a problem with them at all. Just experiment and introduce new things gently. Here is a simple guide on food to get started.
Food size - Always cut up your food scraps before you put them into the compost. I sometimes just break them up with my hands as I add them. It's much easier for the worms to eat when they are in smaller pieces and it will help to minimize how many other bugs you have visiting the compost to eat the remains. If you are leaving town and want the worms to have something to work on for a while, you can give them more of a challenge by leaving the food in bigger pieces. That said, be mindful of what other insects might be attracted to it - if it's sweet you will likely attract ants, mites, and flies that way. I know I said this before (and I'll say it again later, I'm sure), but always make sure the new food you add is sufficiently covered by compost or potting soil. Exposed food scraps will attract insects!
Feeding Frequency - You'll have to feel this out based on the conditions of your compost and how quickly your worms are able to break things down. Start small and then see how long it takes them until the food you gave them is gone. You can use that as a gauge to figure out how much more or less you can give them and how often. In the beginning I had more food scraps from the kitchen than the worms could eat, but now with the two composts I end up feeding each about twice a week. Err on the side of too less food and more worm bedding. They can eat the bedding too, so they will not starve (another good tip if you are going to be away for a while). Adding too much food can cause other insects to get into the compost and it can be tricky to get things back to the right balance.
Mixing - Be sure to mix the new food into the compost so that it is covered completely. It's also okay to add some soil to help keep things covered up. I typically dig a little hole in the compost to put the new food in and then cover it up with compost and a little extra soil. Depending on how moist and dense the compost is, I sometimes will mix the compost around before I add the new food, just to loosen things up so the moisture distributes more evenly. I mix things more than what is typically recommended (they say not to bother the worms), mainly because I use the compost often for the garden. Some worm farmers suggest that you wait until the entire bin is full of compost before you use it on your plants - I did that in the beginning, but I use it more often now and this works fine for me. When mixing the compost use a small hand rake rather than a shovel. Using a shovel will cut the worms, but the hand rake keeps them all in one piece!
Adding Soil - I recommend starting with a little potting soil. The worms need something gritty in order to move around. It also really helps in balancing moisture and covering up the new food that's added. I keep potting soil near my composts for easy access whenever it's in need of a little balancing.
Listening to the Worms - The worms will tell you if they are happy. At first it will be a lot more obvious when they are unhappy - because they will try to escape. When things are balanced you'll see that the worms are happily moving around in the bin, without trying to find a new home. When they have enough food and have a good environment they will also reproduce - A LOT. Don't be surprised if you start with ~100 worms and a couple moths later you look inside and could swear there are at least 1000. It will happen.. and it's great! The little baby worms are teeny tiny and almost completely transparent, but they seem to grow up really fast. Feel free to take a peak at your worms and see how they are doing. Talking to them can help too - just like with the plants!. :) They feel vibrations through their skin.
Other Insects - If you leave your worm compost outside other insects will find their way into it. Some of these visitors are okay as they also help to break down the food. A healthy garden has lots of bugs in the soil too - so you can think of it that way. One way to keep down the additional, unhelpful visitors is to make sure that when you add new food scraps into the compost it is mixed in with the old compost and covered up completely by soil, bedding, and/or compost. If food scraps are left on top of the compost the smell of the food breaking down will attract more insects, especially flies and mites (and ants will find it in the summer). There is a healthy balance of other insects that is okay, but it is also possible to have an infestation if the compost becomes unbalanced. If you keep your compost inside, you should still make sure the new food scraps are buried and covered up so that new friends aren't attracted to it. If you do end up with an infestation - don't panic! That has happened to me before and I just added more potting soil, got it to the right moisture balance, and didn't feed the compost for a little while. Eventually the intruders will leave when the food they went in there for is gone. Just be mindful of what you add to the bin, how much you add, what size the pieces are, and how well it's covered. If you did something that caused unwanted visitors, assess what you did and adjust accordingly after that food is gone. (Pro tip: Do not add a whole watermelon, cantaloupe, honeydew, or other melon rind all at once. Mites LOVE melon. Cut the rind up into pieces and add it gradually to your compost - the worms love it too, but they can't eat it all at once. Keep the other cut up pieces in the fridge or the freezer until the worms are ready for more.)
HOW TO FEED YOUR WORM COMPOST:
Open the bin.
Check out how the worms are doing and if they are ready for more food (is the other food almost gone?).
Does anything look out of balance? (moisture, smell, food scraps, worms trying to escape, insect intruders, etc.)
What other critters are around? (mites, ants, flies, spiders - If outside, in moderation this is all okay. If inside I wouldn't expect any of these.)
Is the compost moist? Is it too wet? (If dry, spray some water in there. If too wet, add some soil or bedding)
Is it smelly? (It needs more air circulation - mix it up and drill more holes.)
Can you see any old food exposed before you dig it up? (It's not buried deep enough.)
Is there a certain food that they don't seem to be eating? (It might be too big or they might not like it!)
If they are ready for more food, dig out a small area to place your new food scraps in.
Add the food scraps.
Cover up the new food scraps with compost, new soil, and/or worm bedding. (I used compost and soil in the pictures below.)
There's lots of other good information about worm composting here.
The coolest part about having a worm compost is that sometimes, when you look inside your compost bin, you'll see that the worms have started to grow their own food! I've found whole beets, carrots, sprouted potatoes, sprouted avocado plants, sprouted squash, and many other foods that they got started for me and then I moved into the garden. The compost is so fertile and the conditions are so perfect that plants sprout much faster in there than any time I've tried sprouting them on my own.
