Friday, September 28, 2018

Vermicomposting Food Scraps

Photo of author's hand with a red wriggler worm in some bedding.

#VeganMoFo18 Day 28 - Vermicomposting Food Scraps

Vermicomposting food scrapssay what? Vermicomposting is a fancy what of saying composting with worms! Cool, right? Heck yeah!

The last post talked about composting your food waste in compost piles, bins, or tumblers. Today we're going to talk about composting them in worm bins. As I eluded to last time, we use both systems for dealing with our food waste.

Photo of a delivery box on front steps that says "Live Worms," in which red wriggler worms were shipped.
Box of Worms in the Mail!
Vermicomposting uses a particular type of worm, called red wriggler or red wiggler, depending on what source you read, sometimes called tiger worms due to their tiger stripe-like banding. Their scientific name are Eisenia fetida. These worms are not the earthworms or nightcrawlers you find when you dig in your yard or garden, nor are they worms you buy at a bait shop, they are the worms you find in piles of wet leaves on the sidewalk, small red worms that break down organic material. While you could search around and find some red wriggler worms among your leaves, it is easiest and most productive to buy them from a composting worm distributor. We got wonderful red wrigglers from NW Redworms, who shipped them to us from Camas, Washington. 

Composting worms can process a surprisingly large amount of material. A red worm can process half of their weight of food scraps a day! So this gives you a number to go by to determine how many worms you need for processing your food scraps. If you estimate you produce about one pound of food scraps a day, you'll want two pounds of red worms. But since the worms will reproduce, start with one pound of worms and let them build up the colony. One pound of red worms will equate to approximately 1,000 breeding worms, so you'll have a lot of worms with just a pound!

Worms eat your scraps and the bedding, and then poop. This poop is called worm castings and is composted food and newspaper scraps! It's really that simple.

Photo of a large wood worm bin outside.
Large Wood Worm Bin Outside
To house your worms, you need an appropriately-sized bin. The rule of thumb is 1 square foot of surface for each pound of worms. There are a multitude of choices for worm bins, whether you build your own from wood or repurpose a plastic storage container, or buy a commercially-made option. Tilth Alliance has instructions for building bins on their website. We started with the Off-the-Shelf worm bin, but had more food waste than that could handle, so we built a large wooden bin to better accommodate our situation. I use the off-the-shelf bin to transport worms to tabling events for Tilth Alliance as part of my Soil and Water Steward outreach activities.

We used strips of newspaper as bedding in our worm bin, for both of the bins. We wet the strips down after separating them and filled the bin about 3/4 full. Like your compost bin, you want the bedding to be damp as a wrung-out sponge, not dripping wet. Worms don't like it if it gets too wet or too dry and will try to escape your bin in search of better conditions.

Photo of a worm bin 3/4 full of strips of damp newspaper bedding with pile of new red worms added on top.
Newspaper Strip Bedding with Pile of New Worms On Top

Where to keep your Worm Bin

Worms like similar temperatures as humans, preferring a climate between 50-80 degrees Fahrenheit. Most resources will tell you to keep them inside your house or garage, protecting them from high heat and freezing temperatures. Lots of people keep them in their closets and basements. The bins don't smell, the worms consume the food so it doesn't rot, so that isn't an issue at all for folks.

We keep our worm bin outside. Alan did not want it inside at all, and, I wasn't too excited about that either. We had the small bin in our garage, but the big bin is just too big, so it lives outside. Even when it was really hot out, the bedding inside stayed cool and damp. In cooler temperatures, worms move into the center of the bin and huddle together to create their own heat. However, they do not withstand freezing temps. This later this fall, before winter, we will move the bin into our greenhouse to keep it from freezing. However, if it does freeze, the adult worms may die, but worm eggs will survive and hatch in the spring.

Feeding your Worms

To feed them, we simply bring out our food scraps, lift up the bedding and place the food on the bottom, making sure to cover the scraps completely. We put food in different spots each time.

Photo of vegetable food scraps (green bean trimmings) in among bedding in worm bin.
Adding Food Scraps to Worm Bin (Corn on the Cob and Green Bean Trimmings) to be Buried with Bedding

If you fail to cover your scraps, you can get fruit flies, which happened to us. To deal with that, remove the food, cover the bedding with additional new bedding, close the bin and don't open it again for about 3 weeks. Your worms will be fine, they'll eat bedding, but the fruit flies won't have enough food, causing them to not reproduce, and by three weeks, they will have met the end of their life cycle and perished. Then you can start feeding your worms again, making sure to bury the food.

The other thing we do to help keep fruit flies out is to put a single layer of cardboard across the entire top surface. This has been a huge help, we think. It also keeps moisture in and helps maintain a constant temperature.

Photo of a layer of cardboard on top of worm bin bedding.
Protective Layer of Cardboard on top of Bedding

Feed your worms:
  • Fruit and vegetable scraps
  • Bread
  • Grains
  • Coffee grounds (some sources say these are too acidic, but they've been fine in ours)
  • Tea
  • Cooked fruit and vegetable scraps, especially from making veggie stock or apple sauce or plate scrapings
Don't feed your worms:
  • Human or animal feces
  • Oil
  • Meat
  • Dairy
  • Fish
Some sources say not to give worms high acid. particularly citrus, or spicy foods, as it could burn the worm's skin. Others say it's ok to add bits of that at a time, but not a huge load of it at once. We simply just put citrus and hot pepper scraps in our compost bin instead.

Other Things that Live in your Worm Bin

You're going to get other things living in your worm bin other than worms, and that's good and normal, most of the time. As I mentioned earlier, you can get fruit flies. They don't harm anything, they're just annoying and I hate breeding them with the chance that they can get inside the house. Other things you can get in your bin:

Good Critters - won't hurt the worms and actually help with decomposition
  • Earwigs
  • White or pot worms
  • Springtails
  • Pill bugs
  • Millipedes
  • Mites
  • Black soldier flies and their larvae
  • Spiders - they kill the flies! We have a big spider who lives in the corner of the lid. We let it be. Sometimes we surprise it and find it on top of the bedding, we're just careful not to bury it. 

Bad Critters
  • Centipedes - can kill worms
  • Earthworm mites - show up if your bin is too wet. Your worms will stop eating if there are too many of these present
  • Ants
  • Roaches - rare, means your bedding is too dry

Harvesting the Worm Castings (Compost)

After four to six months, the bedding starts to turn dark and crumbly, but there's worms mixed in with this compost. Simply move all of the old bedding and castings to one side of the bin and add new bedding to the empty space. Feed the worms ONLY under this new bedding and after a month, most of the worms will have migrated to the new area for food and to get out of their poop (they don't like to live in their castings), and you can harvest mostly-worm-free compost.

Photo of a handful of worm castings with red worms in it.
Castings with Red Wriggler Worms in it

Alan wasn't too excited about the worms at first, but now he is our household worm wrangler! He loves to feed them so he can check on his brood. Any visitor to our house is quickly escorted out to get a personalized introduction to the worms, before they can even answer the question, "You wanna see my worm bin?"  The grandkids are encouraged to explore them as well! 

It's been a great way to keep up with our supply of food scraps. Without the worm bin, we would probably have too much nitrogen-rich material for our compost tumblers, so this helps spread the load. 

Resources about Vermicomposting

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