Do-It-Yourself Worm Casting Methods for Compost

If you’re a homesteader, you probably know all about composting. Composting kitchen scraps are one of the best ways to fertilize your garden without chemicals and pesticides.

Some of the most effective composters use worms to break down food. If you have a worm composter, then you might not know that worm castings – the black waste that worms produce – is arguably the single best fertilizer known to man.

The challenge is finding a way to harvest the worm castings – also known as black gold – without disturbing or harming your worms. You also want to make sure to preserve any eggs in the castings since those will hatch and provide you with a steady supply of worms.

When Is It Time to Harvest?

The first thing to cover is how to know when it’s time to harvest the castings. The best way to tell is to examine the food bedding in the vermicomposter. When most of it appears to be a rich, black soil, it’s time to harvest.

The key is to wait until what you’ll be harvesting is mostly castings. That way, you’ll have the richest possible fertilizer to use.

Method #1: Using Food to Move Worms

The worms in your composter will migrate to new food sources when you provide them. One of the easiest ways to harvest their castings is to move their food source and wait until they’ve relocated.

If you have a multi-tray worm composter, simply move the food to the tray above the one you want to harvest. You’ll have to be patient. The worms may take up to a month to relocate. Once they do, you can simply sift through the tray to find any remaining worms. Place them in the tray with the food.

You’ll also want to be on the lookout for eggs in the soil. Worm eggs are small, round, and a yellowish color. You’ll want to place the eggs in the new food bed. That way, they’ll have a food source when they hatch.

Method #2: Using Light to Relocate Worms

Worms are subterranean creatures who prefer dark to light. In fact, they will naturally turn away from light and migrate to a new location when it’s present.

For that reason, a simple way to move the worms out of the tray you want to harvest is to shine a light at one end of it. They’ll move to the other end and burrow in, leaving you free to sift through the castings, remove remaining worms and eggs, and replace the food bed.

It’s important to note that exposure to direct light can dry out and even kill worms. An alternative method is to gently move the castings down to one end of the tray, creating a mound. The worms near the top will burrow down the bottom. Then, you can scoop castings from the top and sides.

These first two methods are both for people who prefer not to handle their worms.

Method #3: Hand Sorting

The third and final method is to sort through the castings by hand, removing worms and eggs as you go. Some people don’t like this method. However, if you’re not squeamish, it’s arguably the quickest method because you won’t have to wait for the worms to move on their own.

There are two methods you can use. The first is to empty the whole tray and sort through it, picking out worms and eggs and replacing them in the tray with a new food bed for the worms. The second is to sift a handful at a time.

We’ve found that kids love to help with this method. Provided they’re old enough to know not to squeeze the worms, why not let them help?

How do you harvest worm castings? Let us know in the comments!

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