Ready For Use: How To Start Harvesting Worm Castings
Two to three months after you start your vermicompost, you’ll notice a few inches of worm castings ready for harvesting. The brown, earthy-looking, soil-like material at the bottom of your bin is the finished compost your worms made.
You might think that harvesting vermicompost from a home bin can be challenging, especially if you think about how you’re going to separate the finished compost from the remaining bedding and/or food, and the worms themselves.
You can take a handful out of the bin, pick out all the worms and any undigested food, then set the finished compost aside. Although it works, this method can be extremely time-consuming. It requires a strong attention to detail as you are making sure not to harvest worms, eggs, or uncomposted material
There are a few different tricks you can use to harvest your vermicompost.
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Manual harvesting of worm castings is when you want to collect only small amounts of vermicast a few days after the compost pile is stocked with worms. The pile may not be fully decomposed yet, but, you can get some of what has been.
According to Wikipedia: Vermicast (also called worm castings, worm humus, worm manure, or worm feces) is the end-product of the breakdown of organic matter by earthworms. These castings have been shown to contain reduced levels of contaminants and a higher saturation of nutrients than the organic materials before vermicomposting.[
This method is simple: Gather the vermicast by hand or with a trowel then transfer it directly in a container.
During this process, you might need to pick out a few worms individually and return them to the compost bin.
Bulk Harvesting Using A Pyramid Type Heap
This works by gathering the compost and forming a pyramid or a cone-like heap within the composting bin in a part exposed to some light or a light source.
This method of harvesting vermicompost takes advantage of the worm’s natural sensitivity to heat and light. Once the pyramid is exposed to light, the worms will move deeper into the pyramid.
Then you can start collecting the vermicompost from the top, bottom, and sides by hand or trowel.
Screening Or Sieving
If you want to harvest vermicompost any time of the day or night, this method will work without the need for sunlight. It also has the advantage of separating the vermicompost, substrates, and worms from each other with ease.
You can do it manually by using the same tools that people use to screen out rough sand for masonry. This tool is made of fine mesh wire nailed on wood (for easy handling).
Position the screener above a container or flat surface then transfer a small portion of the pile into the sifter. Shake the screener so that the fine vermicompost falls onto the flat surface or container. The same way you might sift flour for a recipe or strain liquid.
Below is what I used. I felt the holes were a little bit big, as many worms fell through. It did keep out the uncomposted items, and let the compost fall through easily, but, I also found it inhumane.
I read that worms can’t feel, but, I have a hard time making that actually compute in my head. Another thing I read is that they run from heat, and light, and are uncomfortable in dry situations – I don’t know how that can be true yet, they can’t feel…
The Stackable Tray Method
You can use a stackable tray system or a work tower in your bin. Add a new tray with fresh bedding and food so the worms will migrate towards to that tray and out of the tray with the finished compost. This process will take some time to complete, as the worms have to move homes. So, it could take a week or two to get most of them moved to their new home.
At this point, the bottom tray will be worm free. You can start harvesting the compost and start all over again by adding the removed tray back to the top.
Migrating The Earthworms
Although it’s not the easiest method, migrating the earthworms first before harvesting is one of the cleanest method to use when harvesting vermicompost. Once the worms detect another source of food, they will abandon the pile with no food left and move to the pile with the new food.
This works similar to the stackable tray method. The method is simple: Add new food to move the earthworms from the current pile they’re in to another pile. Move the old bedding to one side of the bin and add the new bedding and food to the other side of the bin.
Another technique is to construct a new enclosure next to the one with the harvest-ready compost in a way that the two enclosures are butted up to each other with a way for the worms to move from one to the other. The new enclosure should be filled with new and fresh vermicomposting bedding and food.
Once the worms moved to the new bin and the old one is free of worms, it is easier to harvest the vermicompost using a trowel.
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Once you have your vermicompost, you can use it in many different ways! It can be used both indoors and out as a natural fertilizer for your plants, vegetables, grass, or trees. Since it’s richer than other compost, a little goes a very long way.
Your vermicompost is also good in making liquid fertilizer. Not only does it provide more nutrients to your garden, it also suppresses leaf diseases and repels bugs, when sprayed directly onto the leaves.
To make a liquid fertilizer with your vermicompost, you can use an aerator to aerate the tea. A simpler, also effective, method is to use a paper coffee filter and add about a quarter cup of you worm castings and tie the coffee filter up tightly with twine to hold the castings in. Add your “tea bag” to 1 gallon of water and let it “steep” overnight, don’t heat it up, just let it sit. You can stir it if you want to aerate it a bit over the time it sits, but, it’s not a deal breaker, if you don’t.
You can use your “worm tea” as a fertilizer, once a week, or as a foliar spray to nourish and protect the foliage, or just to water your plants – it won’t hurt them just don’t over-water them.
Which harvesting method do you think you prefer?
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