Feeding & Maintenance
This section describes how to feed and maintain your bin over the several months it will take to generate a significant amount of worm castings. Remember that often it is better to be more hands off than to attempt to control every little factor, as a healthy vermicompost system will keep itself balanced better than an overly fussy operator.
Feeding:
As discussed in the Materials and Setup section, worms require a very specific diet. They will eat fruit and vegetable scraps, but not onions, hot peppers, or citrus. Remember that worms are basically one large mucus membrane, so anything that is painful for your eye is extremely uncomfortable for them. Bread, rice, and beans may ferment in the bin, which can reduce oxygen or cause odors that both you and your worms will dislike. These same foods also tend to mold heavily and while mold is not necessarily dangerous for worms you probably don’t want it in your kitchen. Meat, dairy and oils will cause strong odors, possible pathogens, and can introduce pests. Worms absolutely love melons, cantaloupe, and pumpkin.
Healthy, warm, active worms will eat about half their weight per day. If you start with about 1 lb of worms in a small kitchen bin, expect to feed no more than 3.5 lbs per week. It is perfectly fine to underfeed worms, but very bad to overfeed. If worms cannot eat their food quickly enough it will rot and the oxygen level in the bin will drop (see Troubleshooting) and your worms will die.
Feeding can be done in daily increments or in larger weekly amounts. Do not attempt to feed more than a week’s worth of food at once, as it will rot before the worms can get to it. Never, for example, try to tide your worms over with a large amount of food before going on vacation. They are much better off just going without.
Before you feed, consider pre-treating your food scraps. There are several ways to pre-treat food:
- Chop all food with a knife or in a food processor. Remember that food is broken down by microorganisms which are then eaten by worms; the more finely chopped food waste is the greater the surface area for microbes and the faster they will colonize. The worms, in turn, will process the material much faster.
- Freeze (and then thaw) food. When food is frozen, the water in each cell expands and breaks the cell wall, which speeds up decomposition. Freezing also kills any insect larva that may be in the food.
- Microwave (and then cool) food. Like freezing, microwaving can jump start the decomposition process and can kill any pests that may be present.
- Let food sit before feeding. Many people do this anyway simply because they feed their worms produce that has gone bad, but food that has already started decomposing is that much closer to ideal worm food.
You can either feed your worms food that has been pre-treated using one of the above methods or fresh food (though it will take longer for the worms to start eating). To feed, place food waste in a small pile in one corner of your bin and cover it with a similar volume (though much smaller weight) of shredded newspaper. The newspaper acts as a balancing carbon source and helps keep fruit flies away since flies cannot burrow to the food once it is covered. The next time you feed, you may choose to pick a different corner so that over time each area of the bin is generating castings. When feeding the DPW 10-gallon Rubbermaid bin I feed in a 2-inch wide row at one edge of the bin; I will later push all partially eaten material over by 2 inches to clear a new 2 inch row for the next feeding.
Maintenance:
Maintaining a worm bin requires balancing the variables that shape the worm ecosystem. These are the main variables that should be monitored and managed:
Oxygen and moisture counteract each other so these two need to have a very good balance! Worms need oxygen to breathe but they also require moisture. Having good drainage is the best way to maintain these oxygen and moisture levels. Oxygen is also needed to have the food scraps decompose in the bin, so making sure all the airholes and drainage holes stay unclogged and functioning is the most important thing to maintain with your worm bin.
Moisture is similar to oxygen in that they both need to work together to stay balanced. Since we are using a plastic bin, they retain water much better than a wooden bin. However sometimes they can hold water almost too well! Making sure the bins are consistently moist, but not suffocating the worms is important. This is where the drainage hole some into play. It’s always good practice to harvest the worm extract it catches often so air can continuously flow!
Although already mentioned in the previous step, bedding will need to be added often to make sure the levels are consistent. In our case shredded newspaper is the best bedding. This is because the newspaper acts as a carbon source, allows for better airflow, but also retains moisture well. A layer of bedding should be added with every feeding. Dried bedding placed on top of food will help prevent flies and can keep the worms from leaving the bin. Be generous with bedding– the chances that you will overdo it are small, and your worms will love it!
Worms hate light, and will avoid it at all costs. They are very sensitive to UV light, and may be seriously injured or killed if escape is not possible. For this reason, a worm bin must always be completely opaque and should have a lid or thick cover of some kind. You can use light to your advantage, however. Worms have a tendency to try to escape a very new or off-balance bin, but will stay inside if the area just outside the bin is illuminated. Shining a desk lamp at a pile of castings also makes it very easy to separate worms at harvest time as they will simply move away from the light towards the center of the pile and allow the outside to be collected.
Worms do best in the same temperatures as humans, so they are easy to incorporate into our lives. The red wiggler variety is especially tolerant, surviving in temperatures ranging from 40 – 85 degrees Fahrenheit and thriving at an ideal range of 65 – 77 degrees. Worms will be sluggish at low temperatures and more active when warmer (up to a point). If you keep your worms indoors you are almost guaranteed an ideal temperature range with no extra work on your part. Outdoor bins should be kept in sheltered, shaded areas to minimize swing. Bins that are kept in the sun may heat up to much higher temperatures than the ambient air, especially if they are plastic.
Harvesting:
After several months of feeding and maintaining your worm bin, you will start to accumulate worm castings. Follow along to the next step: Harvesting.