How to Vermicompost

Vermicomposting: Overview

When you vermicompost, you have one goal: to keep your worms happy and productive so your harvests are as plentiful as possible. You can also have a secondary goal of encouraging breeding and multiplying, which the worms will be happy to do once your system is set up for success. To reach these goals, focus on two objectives: 1) provide ideal living conditions for your worm colony; and 2) systematize your worm care for an easy, rewarding experience. The following are four main areas to manage as you pursue these objectives.

System Design

The type of system you choose will have more to do with your lifestyle and preferences for the project than it has to do with the worms. Most bins support the darkness, humidity, air flow, and temperature requirements that help worms thrive. Outdoor, uncovered systems are also possible. The laziest way is to just have a pile of composted poop outside – more about this in below in Feedstock. Any of these may be built at home or purchased:

1) Single-bin system with a lid and air holes: This is the simplest and least expensive way to start a worm bin. A plastic storage tote works, or any water-tight container to which air holes may be added. If your air holes are too large and your worms begin to escape, or if your bin becomes contaminated somehow, you can start from scratch without too much extra cost. The single-bin system has few variables to get used to, although you do need to be cautious with the amount of water you add as the system does not allow for drainage. You can easily overcome wet conditions by adding bedding, so a single bin remains a wonderful beginner system. The main drawback to the single bin is that you will spend more time separating your castings from the mixture of worms,  food, and bedding.

2) Stacked Flow-through System: This system consists of at least three inlaid containers: the bottom container catches any fluid that drains from the system, the middle section (of one or more containers) holds the worm colony and their bedding, and the top container holds enticing feedstock and yet more bedding, with a lid. Each container except the bottom one must include side holes for airflow, plus bottom holes for the worms’ migration through the system as they eat their way upwards. The stacked flow-through system has an advantage at harvesting time, because each time you add a new bin of food to the top, you encourage the worms to leave the rich bottom layer of castings. However, since worms are also attracted to water, this style of bin can have mixed results in practice, as water will always drain to the bottom. Sufficiently moist feedstock and correct humidity management may overcome this potential issue.

3) Continuous Flow-through System: This system uses a single lidded container, although it is quite different from the single-bin system described above. The continuous flow-through system requires a hole at the bottom to harvest from, a sliding door, or some other type of closure. A flow-through system can take many forms: a large bag, a plastic tote, or even a raised garden bed. The flow-through method requires very little disturbance of the worms because food and bedding are added to the top of the system, where worms naturally expect food to drop, and the castings naturally amass at the bottom of the system, where they can be accessed via the harvesting opening. This may be one of the more expensive systems styles to design or purchase; however, you can expect simpler maintenance and harvest procedures in return for the setup time and cost.

What to feed

Like outdoor composting, vermicomposting requires a balanced input of “brown” material (rich in carbon) and “green” material (rich in nitrogen). One favourite feedstock of composting worms is pre-composted manure, because it happens to contain both materials in the right proportion. In fact, you can easily use ONLY pre-composted manure as food and bedding. But if you don’t have access to that, there are many other ingredients your worms will love.

Brown:

· Small-chipped wood

· Cardboard and paper (shredded)

· Soil (must be free of pesticides and herbicides)

· Dead leaves

· Coconut coir

Green:

· Grass clippings (spray-free)

· Green leaves or garden trimmings

· Plant-based, unsalted kitchen waste (including coffee grounds)

· Juicer pulp

· Grains, cracked or milled (small amounts only)

Try to shop local or even find your ingredients for free! This is optional of course, but vermicomposting becomes even cheaper and more regenerative when you avoid and reclaim waste.

Here are a few more considerations:

· Do not feed too often or too much – once every 3-14 days is fine. Ensure the existing food has broken down at least halfway before feeding again

· Avoid animal-based foods (except eggshells which add calcium and raise the system’s pH)

· Foods in the citrus and allium families contain worm-repelling oils. They will eventually break down in the bin if cut more finely and kept to small amounts

· Cracked grains should be fed in small amounts only due to high protein content

· Worms are very sensitive to salt

· Mind the moisture in your feedings. Kitchen scraps are almost entirely water

· Bury the fresh food under at least 1-2 inches of bedding to control odour

Harvesting castings

The way castings are harvested will depend on the type of system you use, however in all cases it’s best done immediately before you intend to use the castings. This is because worm castings’ main benefit is the inoculation of millions of microorganisms, which survive best in a moist, dark environment. Usually, you need to sift the castings to remove any worms or large pieces of bedding that came along. This can be done with an 1/8-inch screen; a colander, a larger-holed sifter, or even a wire desk organizer can do the trick.

Continuous flow-through systems are the easiest to harvest: you simply release the castings into a container via the harvesting hole, resecure the hole, and sift as described above.

Stacked flow-through systems are easy to harvest. Harvest once the first feed bin is mostly castings. Simply take the bin out of the stack and sift its contents into a container for use. Then, add new food to the now-empty bin, and move the lid to this bin. This is your new top bin – stack it on top and tip any residual worms and bedding into the current feed bin.

Single-bin systems are more difficult to harvest. Make it easier by not feeding the colony for a few weeks prior to your desired harvest date. This allows the worms to finish off more of the feedstock they left in the bin. After these few weeks you have two choices. You can sift the entire bin, including the worms, or you can coax the worms away from the castings to minimize disturbance during the harvest. This can be done by spot-feeding to one side of the bin, luring the worms to one extreme side so you can remove and sift the castings.

Troubleshooting

All that your worms want is to be left alone. The less time you spend digging through your system, the happier they will be, so feeding times are perfect opportunities to check system conditions. We examine a few common problems below, but keeping these ideal conditions in mind will help you diagnose most issues:

· Worms prefer 70-80% ambient humidity. Standing water or obvious wetness means the system is too wet. Unchecked it may become devoid of oxygen (anaerobic).

· Healthy temperature is 15-30° C. You may want to get a cheap thermometer if you keep the system outdoors.

· Bedding should take up more volume than the worms and feed combined

· Large piles of food sitting too long may rot and overwhelm the bin ecosystem

· Airflow is necessary. Provide air holes and mind whether the worms congregate around them

· Balanced microbial activity is paramount. The bin should smell like a forest floor if anything. Beware foul odours or growths of any mold that isn’t white and threadlike.

Problem: Worms Escaping

Solution: Either the worms don’t like something in your bin, or something they need is missing. Do some detective work using the ideal conditions outlined above. Sterility of a new bin can cause worms some stress. Colonies usually just need time to adjust to their new home, even if conditions are fine.

Problem: Foul Smell

Solution: Pay special attention to moisture, food proportions, and airflow in your system. Also look for dead worms – large amounts of dead worms should warn you of overly acidic or anaerobic conditions. You may need to add bedding, add air holes, and cut down on feeding for a little while until things stabilize. Check the bin frequently to ensure conditions are improving as you make changes.

Problem: Worms Gathering in the Castings Layer

Solution: Worms will naturally explore all layers of a stacked system. They sometimes choose a deeper layer for breeding, and you typically don’t want to discourage breeding behaviour. However, if many, many worms congregate in the bottom layer, ignoring the food and possibly even escaping through drainage holes, the system is too wet. Hold back any addition of water and moist feedstock. Examine the bedding conditions and adjust.

Problem: String-of-Pearls Disease

Solution: You may see this condition if worms have been overfed protein. Worms appear segmented and lumpy, with inconsistent body circumference. Grains and legumes (including coffee grounds) are the highest-protein feedstocks, and you should monitor their levels in the system if you observe these traits. Prevent more worms from suffering this affliction by limiting protein and providing enough carbon-rich “browns” to break down in the system.