Vermicompost
Vermicomposting is a form of composting in which worms are the main decomposers. Because it can be done indoors and takes up relatively little space, it is a great option for people without a backyard. Like with backyard composting, the “end product” (in this case, worm castings) is a nutrient-rich soil amendment that is great for gardens, yards, and houseplants. Vermicomposting is another way to recycle food scraps into a valuable material that improves soil health and promotes plant growth!
Building Your Worm Bin
As with backyard compost bins, there are a number of options for worm bins. You can purchase a pre-made worm bin, make your own single-bin system, or make a multi-tray system. Read more about worm bin types here.
Simple Single-Bin System
To build a single-bin system, you will need:
One 10-20 gallon non-transparent plastic storage tote with lid
Drill & 1/2 inch drill bit
Bedding: shredded newspaper & scrap paper, cut up cardboard & paper bags, shredded egg cartons, ripped up paper towels & napkins. Avoid anything glossy and/or bleached
1/4 - 1/2 cup water
6-8 cups sandy soil from outside
Cut up food scraps (fruits & veggies, pasta & grains, egg shells, coffee grounds, tea leaves. Avoid citrus, onion, garlic, spicy foods like hot peppers, pickled foods, oils & fats, and meat & dairy)
1lb red wiggler worms (Eisenia Fetida)*
*Red wigglers are a different species than the earthworms in your garden. You can order red wigglers online from these retailers.
Assembling the Bin
Wash out the storage tote and lid.
Drill 1/2 inch holes around the top of the storage tote, about 1 inch apart.
Dampen the bedding materials by soaking in water and wringing out. They should be about as wet as a wrung-out sponge.
Fill the bottom of the container (a few inches deep) with moist bedding. Mix in a few cups of soil. Add a bit more water if the soil is dry.
Add food scraps and worms. Once acclimated, red wigglers can eat up to their body weight in food every day! Start with a ratio of 2:1 worms-to-food and monitor how quickly they go through the food scraps. You can adjust this ratio over time based on how the worms are doing.
Cover food scraps and worms with another layer of soil, and mix in some water if the soil is dry.
Top it all off with another couple inches of moist bedding. Always make sure to cover worms after feeding them!
Place lid on container and store in a dark place (in a closet or cabinet works great). Keep the bin in ~60-75 degree temperature range.
Feeding the Worms
Feed the worms about once every week. The worms may take some time to adapt to their new home; they will likely need less food at first. If the food seems untouched when you check the bin, hold off on feeding for another week. If the food is completely disappearing, you might need to feed them more; if most of the food is gone from the previous week, feed them the same amount. It usually takes about a month to get a feel for how much to feed the worms.
To feed, roll back the top layer of bedding to expose the worms. Add in chopped up food scraps, sprinkle with some soil, and cover with bedding. If the bedding seems dry, spray it with some water. Add more moistened bedding as the older bedding starts to break down and disappear.
Harvesting Worm Castings
In about 3-5 months (or when you notice a lot less bedding and more compost in the bin), you can harvest the castings. To harvest, push all the contents of the bin to one side, then put fresh bedding, soil, and food scraps in the empty side. Over the next couple weeks, only add food scraps to the side with the fresh bedding. The worms will migrate over to that side, leaving the compost on the other side for you to harvest! In 2-3 weeks, collect compost from that side, and replace with new bedding and soil.
Using worm Castings
You can use worm castings much like you would regular compost - on your yard & lawn, in garden beds, and in potted plants!