Have your kids ever asked for an ant farm? Get an indoor vermicomposter instead and turn your kitchen scraps into rich compost. Teach your kids all about biological life cycles and organic living with this fun family or classroom project where you create your own indoor compost bin.
Vermicomposters are small indoor compost bins that use live worms to turn kitchen scraps into your own healthy plant food. The worm castings, or vermicompost, is extremely rich in helpful microbes and bacteria, and acts as a nutrient-rich fertilizer. There are many different types of vermicomposters, some small and simple enough to be kept on a kitchen counter. Store bought compost can be expensive and does not pack the same nutritious punch. Compared to normal potting soil, vermicompost contains 5 times more nitrogen, 7 times more phosphorus, and 11 times more potassium. They are full of humic acid and greatly improve soil structure. Vermicomposter prices range from $70-$100 and starter kits with worms cost around $25.
In the same way that children learn to raise caterpillars in elementary school, observing the life cycle of worms within an indoor compost bin is an extremely interesting family project. Worms are among the most important organisms in the world because of their ability to amend and condition soil to make it rich and fertile. Without them, agriculture would not be possible. Teach your children about the importance of organic living and watch your plants reap the benefits.
Step 1 - Choose Your Vermicomposter
When choosing a vermicomposter, look for something that can fit indoors. Large bins can be built for outdoor use, but for the beginner a small inside environment is easier to control. You can build your own indoor vermicomposter, but small flaws such as too little drainage or ventilation can cause huge problems. Splurging a little for a store bought composter makes this project hugely simple and absolutely rewarding. The best type of vermicomposter for inside use is called a Continuous Vertical Flow composter. This design uses layers of plastic bins stacked on one another. The bottom tray is filled with bedding, worms, and kitchen scraps. As the worms finish composting in the bottom trays they travel upwards to find more food. The bottom trays of your indoor compost bin fill with processed compost that can be removed for use.
Another very helpful feature to look for is a vermi-tea spigot. Vermi-tea is the nutrient-rich liquid released in the composting process. The liquids flow into a container in the bottom of the composter and can be harvested at any time through a handy built-in spigot. This tea is used to water your indoor and outdoor plants, straight or diluted, and is among the best fertilizers known to man. A good vermicomposter also comes with built in odor control, such as a charcoal insert.
You can buy your vermicomposter at a nursery or home store, or order one online. Though many sizes are available, the 16x13x16-inch model is a very manageable size and ends up weighing around 12 pounds. When your indoor compost bin arrives, you should place it in a dark spot, well away from any direct sunlight or sources of extreme heat or cold. It is most convenient to keep yours in the kitchen to easily dispose of kitchen scraps. An ideal place is under the sink.
Step 2 - Choose Your Bedding
Your new worm friends will be eating your kitchen scraps, but still need a medium in which to live. You can buy commercial worm bedding at nursery stores or online, but it tends to be pricey. Thankfully, bedding can be made with things you have at home or at the office. Shredded corrugated cardboard or shredded paper makes a simple and easy bedding. Newspaper and computer paper is ideal, and the ink is organic and fine for the worms. You can also use aged straw, coconut coir, fall leaves, or peat moss, and ideally a combination of 2 to 3 different bedding types. The worms seem to prefer fall leaves and shredded cardboard. Avoid glossy paper like that from a magazine for your indoor compost bin. The amount of bedding you need depends on the size of your composter. A 16x13x16-inch box needs between 2 and 3 pounds of dry bedding.
Step 3 - Choose Your Worms
There is a particular kind of worm you should use in your indoor compost bin. It is called the red worm (Eisenia foetida), also called red wigglers or tiger worms. They can be ordered online or through gardening catalogs. You may be able to find them in bait shops, but they are typically not the healthiest specimens. Contacting your local gardening club and asking to buy worms from fellow composters can be a wonderfully cheap way to get them. The amount of worms you need depends on how much kitchen scraps you generate each day. Before purchasing your red worms, keep track of how much waste you produce each day for a week. One pound of worms can dispose of one half-pound of non-fatty kitchen scraps each day.
Do not try to use night crawlers or any other type of worm in your vermicomposter. These worms can only live in deep soil with colder temperatures and will not survive in a bin.
Step 4 - Prepare the Bedding
The worm bedding needs to remain nice and moist, mimicking the normal living conditions of the fully underground organism. Let your children help you place the dry bedding in a large container and cover the bedding with water. Allow the bedding to soak overnight until it is fully saturated. Explain that worms absorb moisture through their thin skin and without it they can easily dry out and die. That's why keeping their home moist is so important.
Bacteria and microbes that aid in digestion are essential components of vermicomposting for your indoor compost bin. These organisms will not be present in your bin until food is added and begins to break down, so one interesting option is to soak your bedding in moist kitchen scraps, like vegetable pulp and juice. Saturate in a closed container for about a week before draining and adding it (and the worms) to your composter. This creates a very happy environment for your new worms.
Before placing your bedding in the bottom tray, ring out as much liquid as possible until it has the texture of a rung-out kitchen sponge. Place the bedding in the bottom tray and fluff it up. Remember that your bedding needs to remain moist. Fill a spray bottle with water and keep it next to your composter so you can give the bedding a good spray when needed. This is a great chore for older kids.
Place your newly prepared bin under a strong light and sprinkle your red worms on top of the moist bedding. The worms are light sensitive and will quickly wriggle under the bedding to avoid it. They will soon settle into their new home!
Step 5 - Feed Your Friends
Your worms can turn many different types of kitchen scraps into food. Any part of fruits or vegetables are great, as well as tea bags, coffee grounds and filters, shredded paper, crushed eggshells, and plain pasta. Occasionally adding gritty material to the kitchen scraps, like dry crushed eggshells, coffee grounds, or cornmeal can be very beneficial for the worm's digestion. Avoid anything with fat, oil, dairy, meat scraps or bone. Some say that very small amounts of these materials can provide protein, but substantial amounts can attract other pests to your indoor compost bin. Chopping the kitchen scraps up into small pieces and feeding the worms more leafy vegetables and less fruits can cut down on odors. Be particularly sparing with citrus, which can be especially pungent.
When you start feeding your worms, the day after introducing them to their new habitat, begin sparingly. The best method is to pull back a small amount of bedding and bury 0.5-cups of kitchen scraps inside the indent. Cover them with 1-inch of bedding. Every few days check back on the worms, looking at the scraps and keeping the bedding moist. If food scraps still remain, cover them with more bedding and wait before you feed your worms again. Only feed your worms again when 95% of the kitchen scraps are gone. This could take up to a week in the beginning. If certain scraps remain after 2 weeks, remove them from the bin. If you notice one particular type of scrap is always left behind in your indoor compost bin, leave it out in the future. As your worm colony grows, they will consume more food, so keep an eye on how fast they devour their meals. You should be feeding an established colony about 1 cup of food every 3-5 days.
Start feeding on 1 side of the bin and work your way through the whole thing. By the time you get back to the beginning, the first kitchen scraps should be converted into usable compost. Start slow with feeding. It will take time for beneficial bacteria to form and your bin could become very smelly if you add too much food too fast.
Step 6 - Harvest Your Compost
Inspect your indoor compost bin every few days, making sure to keep the bedding moist. Watch as your worms quickly digest their food, moving through the bottom bin. In 3 to 4 months your worms will have digested nearly all of the scraps and bedding and the bin will be filled with black soil-like fertilizer. At this point is it time to prepare for harvesting, so do not add any new kitchen scraps for 2 weeks.
When the bottom bin is full of compost fill another bin with moist fresh bedding and some food and place it on top of the first. Wait for 48 hours for the worms to wriggle up to the fresh food. Then, detach the bottom bin and use your compost. Inside, you may find seeds that have germinated, toss these. You may also find small opaque pods that are actually worm egg sacks. Show these to your kids before simply placing them into the new bin. You may be able to raise some baby worms! Baby worms appear small and white. Worms may die inside the bin but thankfully neither you nor your children will ever have to see them, as they simply shrivel up.
Step 7 - Use Your Home-Made Compost
For indoor potted plants, spread a layer of vemicompost on top of the potting soil and water well. In your yard, add a few handfuls of vermicompost from your indoor compost bin into newly dug holes before planting shrubs or trees. If you find yourself with a surplus, work a few pounds of vermicompost into your garden soil the day before planting your annual or veggie beds. This compost is all natural and very safe, it will not burn new roots like many commercial fertilizers will. You should also water both your indoor and outdoor plants with the organic vermi-tea and watch with your kids as your plants flourish!
Traditional composters need time and energy to produce usable compost. With a vermicomposter, your worms do all of the work, and are happy to do it! Taking care of the worms, and using your organic compost, is a fun DIY project for any family or classroom.
(If you're not squeamish about worms, maybe you're not squeamish about nature's other fertilizer, manure.)