Vermicomposting: Worm Composting Indoors, Part Two
A home for your worm bin
Worms are flexible in terms of temperature, withstanding occasional temperatures of 38F to 95F. However, these extremes could kill your babies if left for long periods of time. Best is a range of 60F to 80F, with cool room temperature ideal. Locate your composter in a corner of the kitchen, in the basement, or in a garage, porch or sheltered area of the garden.
Avoid placing in direct sun. Worms are photophobic; and sunlight can quickly heat the bin like a hot car in a parking lot.
The first article included a list of foods suitable for the composter. Within two weeks of starting your bin, you’ll notice a distinct change: a growth of molds, an ‘earthy’ smell. This is called a ‘bloom’ and is a positive stage in the development of the microbial environment needed by your worms. It hastens the rotting of the food and promotes growth of bacteria and fungi which provide nutrients for your squirmy friends.
How much you feed your worms depends on how many worms you started with, how old they were when introduced, and how comfy they are in their environment (comfy enough to reproduce, that is!). Start with about two pounds of food. Pull back the top 2”-3” of bedding on one side (I use a three-pronged hand cultivator), drop in the food and cover it up.
You should check your bin and feed it at least once a week. If you put food in one half of the bin one week and the other half next time, you can keep track of how fast your worms are eating and adjust your feeding amounts accordingly. Try not to check too frequently, as they don’t like being disturbed. This will be hard for children – I know it was for me!
Your worms actually consume the bedding as well as the food, and you might have to add more as worm castings begin to fill the bottom layer. Just add another 2-3 inches of damp shredded newspaper on top and starting depositing food on top of the former top layer. If the top layer dries out from time to time, spritz with water. If the bottom layer is too dense and starts to smell bad, use a cultivator to fluff it lightly: gently insert the cultivator and lift, shaking slowly to allow air pockets to form. This allows oxygen circulation and reduces smell-producing anaerobic activity.
Leachate will normally collect in the boot tray under the bin; dilute it and use on outdoor plants as you would a compost or manure tea.
Unhappy worms will try to flee, and you’ll see them on the walls and lid of your bin. Check temperature, humidity and density of the bottom layer. Review your feeding frequency and amounts.
Fruit flies are common. I move the bin outside and take the lid off for a while (especially when it’s below freezing), then throw a few sprigs of fresh mint on top of the bedding and replace the lid. You can also make a trap (a jar containing some mashed fruit, with a funnel taped to the mouth) and place it on top of or even in the bin.
Once worms reach sexual maturity (8-10 weeks from hatching) they will begin to reproduce, producing ‘cocoons’ or egg casings about the size of a large grapeseed, coloured pearly grey to yellow to ‘cola’ as they mature (average hatching time is seven weeks). Mature worms can produce about 10 babies each weekly under ideal conditions, and your ‘poundage’ of worms can double in 3-4 months. The cyan squares in the photo show egg casings.
I’ll describe two methods of harvesting; there are many.
1. Stacks. This method takes advantage of the worms’ fear of light. Spread a plastic drop-cloth on a sunny floor and build several 8”-10” stacks of compost. The worms will burrow to the centre. After an hour, remove the outer few inches of compost; again the worms will burrow to the centre. Continue, combining the stacks occasionally, until most of the compost is harvested. Return the worms to a new bin. This method takes a day but is labour-intensive.
2. Migration. Stop feeding your worms for a month before harvest. Construct a wood or bamboo frame covered with hardware cloth, measuring slightly smaller than your bin’s dimensions. Place it on the surface of your bedding, add a layer of bedding, food, and more bedding. The hungry worms will find the food and establish a new residence. When you observe a concentration of worms, move them to a second bin to start a new colony. You can do this a second or third time, or just do it once and use the old bin’s compost right away. This method takes 2-3 months but the worms do the work!
Using your compost
Worm compost is alive with microbes, enzymes and nutrients, is water-soluble and provides good tilth for your soil. Use it like regular compost; it’s especially good in the bottom of a hole or container when you’re transplanting, or as a top dressing, worked in.
If you’re worried about introducing the worms into the environment (or your home, for houseplants), put the compost into a plastic bag and freeze for a week.
Once you’ve tried vermicomposting, you’ll find this way of recycling your vegetative waste into garden compost a productive hobby and a great conversation topic at parties. A natural for your child’s science project!