April 16, 2013

Earth day activity for kids: How to make a worm bin

3 minutes
Cultural exchange

Let’s face it: kids like worms and other gross creatures.  This is a great Earth Day activity for kids to do with your au pair because it lets them play with worms and make dirt!  It’s great for your family because it reduces your waste and creates free compost to make your garden or indoor plants thrive. Vermicomposting, or worm composting, makes it easy to recycle your food waste and make compost to use in your vegetable garden. Worms can eat half their weight in food scraps each day!


Worm bin basics
Use the redworm Eisenia Fetida (red wiggler), not the commonly found  “earthworm” from your garden. Redworms are readily available from a friend’s compost pile, a local fish bait supplier (you’ll need to be specific about the species you need), or online.

Setting up the worm bin
A bin, worm bedding, water, and food scraps are all you’ll need to add. Place the worm bin where the temperatures will range from 50 – 80 degrees Fahrenheit. Keep it away from heat sources (radiators) and cold drafts (doors and windows). A cool dark spot is optimum.


What kind of bin
You can use a plastic storage bin, wooden crate, old cooler, or a store bought version. The important thing is that it is the right size and allows for air circulation. To prevent compaction and increased toxicity of your bin, make sure the bin is no taller than 15 inches. Here is a guide to see what size bin you need:

Number of people  Quantity of worms Bin size
1 or 2 1lb. 15″ h x 1.5′ w x 2′ l
2 or 3 1lb. 15″ h x 2′ w x 2′ l
4 to 6 2-3lbs. 15″ h x 2′ w x 3.5′ l


Worm bedding
Worm bedding helps keep the worms moist and allows food scraps to be buried to prevent odors. Shredded black and white newspaper works well for “grit” to help the worms digest and is an additional way to recycle. You can also add coir bricks, which are made from ground up coconut husks.

Worms need moisture, not a flood. Worms are 75-90 percent water. Because they breathe through their skin, it is important that the worms stay moist. After shredding the bedding, add water and check for moisture: squeezing a handful of bedding should produce a few drops of water. If it is too wet, add more dry bedding.


Worms need a balanced diet, just like you and me.


Food scrap container tips:
1. Cover the food with the bedding to prevent odors and fruit flies from invading your bin.
2. Store food scraps in a sealed container (to avoid odors). Add small amounts of scraps initially to the worm bin. As the worm population grows, a larger amount of scraps can be added periodically.
3. Chop or tear the food scraps before adding them to the bin. The more you break it down for them, the faster they will work!


Worm food rotation
You can feed the worms in a rotating pattern, burying the food in a different spot each day.


Two ways to harvest your compost
1. Harvest the compost by placing the worm bin contents on a plastic sheet. A bright light placed overhead will cause the worms to crawl to the bottom of the pile. You can scoop off the compost from the top of the pile while the worms hide from the light.
2. Move the contents of the bin to one side and add fresh bedding and food to the other side. A bright light focused on the side with the worms will encourage the worms to crawl to the other side. When the worms move into the new bedding, you can remove the finished compost.


Worm compost uses
Potting mix: Mix together 1/4 part worm compost, which adds nutrients, 1/4 part s sphagnum moss, which holds moisture, 1/4 part perlite which increases aeration, and 1/4 part sand or soil which adds body.
Container plants: Spread worm compost up to 1/4 inch deep on the top of container plant soil.
Seedling transplant: Sprinkle worm compost in the seed row or the hole where the garden plant is transplanted.
Compost Tea: Dissolve worm castings in water (with or without aeration) and use to water plants or as foliar spray


Thanks to Francey Slater and Lydia Sisson of Mill City Grows in Lowell, MA for this great DIY Earth Day activity for kids and the whole family.