Composting with worms (vermicomposting) is a sustainable and environmentally friendly way to recycle food scraps and put them to use in the garden. It’s inexpensive and fun and can be done year-round.
Worm bins take up very little space and can be located in your kitchen, laundry room, garage, or anywhere that’s convenient. In fact, Greenhill Worm Farm is in a garage! Once your worm bin is up and running, the worms will multiply on their own and their food is free! Your composting worms will eventually turn their food and bedding into an all-natural, microbe-rich soil conditioner packed with plant-boosting nutrients.
Composting with worms requires planning, preparation and consistent care. The instructions below will ensure your worm friends are happy and healthy, with all the right conditions to provide your very own organic plant food.
Materials Needed to Start a Worm Bin
Storage bin – 18 to 20 gallon, dark-colored plastic (not see-through)
Drill with 1/8 inch bit – for making drainage and ventilation holes
Bedding – shredded newspaper or cardboard, moistened
Food – kitchen scraps – here is our Red Wiggler feeding guide.
Worms: 1/2 to 1 pound of composting worms (500-1000 worms)
Step by Step Instructions for Setting up A Worm Bin
Step 1: Prepare the Bin
Drill about 20 evenly-spaced 1/8 inch holes in the bottom of the bin. These holes will provide drainage if needed.
Drill a row of 1/8 inch ventilation holes about 2 inches apart on all 4 sides of the bin. Drill the holes about 3 inches down from the top of the bin.
Step 2: Prepare the Bedding
Your worm bedding can be shredded newspaper and/or cardboard. Use a shredder or just tear the paper or cardboard into small strips by hand. A good size to aim for if shredding by hand is 1 – 2 inches wide and 4 – 5 inches long, but it’s ok if the sizes vary.
Newspapers should not contain glossy or colored pages, and cardboard should be mostly brown with minimal colored ink or lettering. You can use cardboard from shipping boxes, paper towel or toilet paper rolls, egg cartons, fast food “to go” drink holders, or other sources. Worms especially love corrugated cardboard!
Worms need bedding that is moist but not soggy or dripping. Soak the bedding in water for a few minutes and squeeze out the excess. Thicker corrugated cardboard may have to soak longer to get thoroughly wet.
Fill bin about 1/2 to 1/3 full with the moist bedding, fluffed up.
Step 3: Add Food Scraps
About a week to several days before adding worms, place a small amount of food scraps in each corner of your bin. Banana peels or apple cores are good choices for this. Resist the temptation to add more than just a handful of scraps as you only need a small amount to get things started.
Worms’ main source of nutrition comes from the microorganisms that grow on fruit and vegetable waste as it starts to decompose. That’s why it’s a good idea to prepare the bedding and add food to the bin ahead of time. However, if you can’t do this beforehand, don’t be too concerned. Your worms will wait around until there are enough microbes on the surface of the food before they start to eat.
Step 4: Add Worms
Dig down in the middle of the bedding and gently place your worms in the bin. Cover them lightly with the bedding. Worms will burrow further into the bedding as they explore their new home.
A good amount of worms for an 18 – 20 gallon bin is anywhere from 1/2 to 1 pound of worms. With the right care, your worms will populate the bin on their own to an appropriate level.
Cut a piece of cardboard or black plastic to cover the bedding. Worms do not like light and the covering will help them acclimate more easily. You can put the lid on the bin, but worms also need air flow and they will receive more fresh air without the lid.
Leave the worms alone for a few days to settle in before you give them more food. They will feed off the bedding, so they won’t go hungry.
Step 5: Feed Your Worms
Start by feeding small amounts of food. A few handfuls at a time are plenty in the beginning. If there is more food than the worms can consume in a few days, the extra food may start to ferment. Smaller-sized meals will help ensure the worms are able to process all of the food. As the worms multiply, you can begin to add more food.
To kickstart the decomposition process, chop food into smaller pieces. You can also freeze the food scraps. After thawing, drain the excess liquid before feeding.
Place the food near the top of the bin and cover it with 3 to 4 inches of bedding. This will to keep it from attracting flies and other pests. Put the food in different sections of the bin each time you feed. This will ensure the worms move around to process all areas of the bin.
Take note of the amount of food you provide and how long it takes the worms to consume it. Make sure all of the food is gone before adding more. Overfeeding is the most common mistake and can lead to fermenting food before your worms have a chance to consume it all. Fermenting food means a stinky bin!
Step 6: Monitor Your Bin
It is important to monitor your worm bin on a regular basis. Red Wigglers are very hardy and will adapt to a variety of conditions, but certain criteria are necessary for your worms to thrive and reproduce.
LOCATION – Place your bin in a convenient, well-ventilated area such as a garage, laundry room, covered balcony, deck or porch. You can put the lid of the bin underneath it to protect floor surfaces. You can also keep your bin outside if temperatures permit, but be sure to shield it from hot sun and rain.
MOISTURE – The contents of your bin should feel like a damp sponge. Pick up a handful of bedding and squeeze it in your hand. If you can squeeze out only one or two drops of water, the moisture is at an appropriate level. If you can squeeze out more than a few drops of water, the contents are too wet. If the contents are too wet, add some dry bedding to decrease the moisture level. If the bedding is too dry, lightly spray or mist with water. Worms breathe through their skin and their skin must stay moist. Never pour water directly into the bin.
TEMPERATURE – Red Wigglers generally prefer temperatures in the 60 to 80 degree F range. They will tolerate temperatures a little higher or lower than this, but not for long. If the temperature is too hot or too cold, your worms may become less productive and not eat as often or as much.
AIR FLOW – Worms need an aerobic (oxygen-rich) environment. The holes drilled in the bin will help with air flow, but it is also beneficial to keep your bin in a well ventilated area. If the bedding gets packed down, stir or fluff up the contents to encourage good air circulation. Leaving the lid off the bin also helps.
Step 7: Harvest Your Castings
As your worms grow and do their work, your bin will start to reveal more and more worm castings. Worm castings (vermicompost) are what’s left behind as worms consume their food and bedding. They should be brown and earthy-looking and not smell bad.
At around 3 or 4 months, it’s time to harvest the worm castings and give your worms new bedding. Pour the contents of the bin onto a tarp or piece of plastic and separate the worms from the castings. Worm castings are packed with plant nutrients and beneficial organisms that will condition your soil and feed your plants. Take advantage of this amazing soil amendment by applying it to houseplants, flowers, vegetable plants, or anything that grows! You may notice that your worms have increased in numbers. They reproduce rapidly when conditions are favorable. Prepare the new bin, add worms, and you’re off again on the wonderful journey of recycling with worms!
Bonus Tips for Vermicomposting Success
Size Matters
You will be much better cushioned against your own errors with a more expansive environment where worms can better escape the effects of overfeeding, overwatering, under watering or other errors you may make at first. Think of worm bin size as a buffer against bad things happening. An 18-gallon tote is a safe size for beginners.
Air Matters Too
Worm composting is an aerobic process and the quality of your castings is strongly correlated to maintaining highly aerobic conditions in your bed. If the bedding in the bin becomes packed or condensed, chances are there is not enough air getting to the worms or to the bedding material.
Don’t Feed Every Day
The worms will do just fine with a feeding every few days and if you happen to even go a couple weeks without feeding, any negative effects are far less than what will happen if you overfeed them.
Remember to Keep Adding Bedding
You can never have too much bedding. While it’s not necessary to add bedding with every feeding, you should add material such as shredded paper, cardboard, shredded leaves, and maybe even wood chips from time to time. Adding bedding helps encourage appropriate moisture levels as well as maintaining aerobic conditions in your bin.