by Diana Brooks, MG Class of 2013
I know that many of you Master Gardeners compost in various ways. Yard waste, for sure. Many of you probably already have worm bins. But for those of you who have not tried vermicomposting yet and might like to know more, this article is for you.
I won’t preach. You already know the benefits of composting food: keeps the methane-producing decomposing food out of the landfill; produces black-gold for your garden; saves you money; and you get to have a clear conscience when you find spoiled food in the fridge: it gets re-purposed as worm food.
Right now is a good time to experiment with your first worm bin! It’s super-easy. All you need is get started is 1) a container with a tight-fitting lid; 2) some worms; 3) some shredded newspaper or sawdust for bedding. Easy 10-step directions follow:
1. MAKE A WORM BIN: If you want a worm bin TODAY, find an opaque (not clear) plastic storage bin with a tight-fitting lid (14 gallon tub is good), drill lots of 1/2” holes in the bottom for drainage, about 1” apart, and holes all around the sides at the top rim for ventilation.
2. ADD BEDDING: The worms like LIGHT and FLUFFY bedding. We like light and fluffy for them because it cuts down on odor. Shredded newspaper is a popular option; other options are shredded fall leaves, shredded cardboard, sawdust, chopped straw, chopped seaweed, compost, and aged manure. You can and should mix and match to create a richer compost. Fill the bin about 2/3rds full.
*Newspaper will shred satisfyingly straight, by hand, if you hold it in the correct position and rip down; experiment.
*Plastic bins retain moisture, which can become an issue for you and your worms. Anaerobic=stinky; also, your worms might drown. I learned from Master Gardener Larry Wight that sawdust from untreated wood makes wonderful light and fluffy bedding, especially when mixed with coffee grounds. Works great in my bin!
*Gently stir the bedding from time to time to let more air in and prevent odor build-up.
3. MOISTEN THE BEDDING: You don’t want to drown your worms with overly wet, anaerobic conditions, but you don’t want to dry them out either; they need moisture to breathe and to slither around in the bin. The perfect bedding conditions would be as moist as a squeezed-out sponge.
Tip: I use a misting spray bottle and keep it by the bin.
4. ADD SOME GRIT: Throw in a handful of dirt or sand; it helps with their digestion. You really only need to do this when first setting up the bin, or when starting over with new bedding, after harvesting the worm castings and worms.
5. ADD WORMS: Make a little hole/depression in the bedding and add about a yogurt container-full of worms, about 1 pound. IMPORTANT: You want Red Worms, aka Red Wigglers, aka fishing worms. You can buy them on-line, but that is expensive. The good news is that you can get FREE WORMS if you know someone who has a horse or cow or alpaca; red worms like to hang out under rotting manure piles. Or…ask another Master Gardener who’s into worm composting. Worms multiply very rapidly!
6. ADD FOOD: Above the spot where you buried the worms, place a handful of yummy vegetarian food scraps: maybe some tender lettuce leaves, some carrot peel and a few fruit peelings. You want to start slowly with a light meal. (Worm diet: Vegetable and fruit scraps, grains, cereals, pulverized egg shells, tea bags, and coffee grounds. NO meat, bones, dairy, oily foods, salad dressings, candy or chips). Then cover the food with a layer of bedding to discourage fruit flies and odor.
*Keep a food scrap bucket near your sink. Line the bucket with a reused plastic food bag; makes emptying the can much easier and cleaner.
*Chop the food scraps.The smaller the pieces, the faster the decomposition. You don’t have to go crazy chopping them up into minuscule pieces, but a little chopping will go a long way and result in a finer-textured compost.
*Calcium is good for garden soil, but eggshell-debris may not be the look you like in your garden. You can either finely crush/pulverize the egg shells before giving them to the worms, or you can choose not to put them in the worm bin. I do both, depending on the day. When I feel like crushing them, I put the dried out eggshells in a dish towel and run over them with a rolling pin.
7. CHOOSE A GOOD LOCATION FOR THE BIN: Worms need to be protected from direct sun, wind and extreme temperature. No problem: choose shade or part-shade. Some people keep their bins inside, in the basement or even in the kitchen. Other options: In a shed, on a porch or in the garage. The best location, according to the experts, is in a garage or shed. I keep mine outside, in the yard, under a tree. (Just be mindful of extreme cold in the winter; I know someone, intimately, who wraps a fleece blanket around her bin when it’s below freezing).
Tip: Raise the bin off the ground a little bit, with bricks or a pallet. Easier on your back; provides additional air circulation; and you can tell if the worms are trying to get out: a sure sign of poor bin conditions.
8. BE PATIENT: It takes a while for things to get going. The worms need time to get used to their new home. And enough time to process their first meal. It may take a few weeks. You can peek in anytime and see how much food is left. Eventually, the worms will work faster; they can eat up to half their body weight in one day.
Tip: You won’t see anything unless you poke around in the bedding. If you are squeamish about that, try wearing surgical gloves and use a trowel, gently; I usually wear my gardening gloves, but I have been known to handle my worms ungloved, with no negative side effects.
9. FEED AGAIN, IN A NEW FOOD HOLE: When the food scraps are almost gone, or when there are only some large pieces of food left, it is time to make a new food deposit in a new hole, next to the previous food hole. The worms will migrate to their new trough. This time you can give them a bigger meal.
10. HARVEST YOUR COMPOST: After 3 – 5 months you should be able to harvest the rich worm castings. Next article will cover this process.
Before I wrap this up, I’d like to share a little worm composting wisdom. There are many different ways to do it, from the scientific to the shoot-from-your-hip. Some of the best advice I ever received was to keep it simple and not fret about it.
I know some people who compost their food scraps in a large plastic garbage can, with holes in the bottom and around the rim. They just keep adding layers of food and newspaper (sometimes not even shredded) and their can is full of worms eating their garbage. They let it fill up to the top, take out a starter-number of worms which they put in a second garbage can. Then they put the lid back on the first and leave it alone. Within a year, the first bin is completely composted. Some people will tell you that the garbage can method is not good because it is so deep that the bedding compresses and smothers the worms; that is obviously not always the case.A “food digester” is another beautifully simple method for composting food scraps with no work involved at all, other than the up-front drilling of holes in a galvanized can with a tight lid, and digging a hole in your yard in which to insert it. No bedding involved. You just dump all your food waste into the can until it is full. Eventually, it will all decompose and turn into compost.
Tip: What do you do when you have too many food scraps? I have one of those food digesters in my yard to take care of food scrap overload; highly recommended. I also put into the food digester the foods that worms are supposedly not particularly fond of: citrus and onion. Also thrown into the digester: food that takes a long time to break down, like artichokes and thick stems.
For more information on composting with worms, and plans for making bins, including a how-to make- a-worm-bin video, and directions for making a food scrap digester, see links below.
Happy Worm Composting!
Food Composting: How to Construct a Compost Bin, Pierce County Public Works & Utilities Video
Composting and Recycling Publications and Fact Sheets. WSU Whatcom County Extension
Composting with Worms, WSU King County Extension
Homemade Food Scrap Digester, Seattle Tilth