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Benefits of Worm Castings in your Garden (Black Gold)

Updated: Apr 5, 2022

Worm castings are commonly called Black Gold, but why? In this article, I'm going to explain why worm castings are an invaluable source of enrichment to your plants.

A man holding a clump of soil with worms in it


A typical day in the life of a worm consists of nothing but eating its way through the soil.

A portrait of Charles Darwin

Charles Darwin is known obviously for the human evolution process, not many people know that he wrote one of the first complete works on earthworms after studying them intensely.

He stated “all the vegetable mould over the whole country has passed many times through, and will again pass many times through, the intestinal canals of worms”.

Charles Darwin brought the awareness of worm castings, at a time when worms were considered slimy, blind pests that pooped on neat lawns and nibbled at roots. Now, we recognise worms to be one of the most beneficial organisms on the earth.

By eating the soil, they're actually sorting through the soil for tiny bits of dead organic matter. The worm eats the soil and mixes it with its intestinal enzymes, bacteria, and liquids, and the end product is released as worm castings in other words worm poop.

Two worm bins placed in an indoor patio

The worms’ intestinal cavities begin to release the nutrients chemically locked up in the decaying organic matter, that wouldn’t otherwise be available for plants to take up.

Worms also produce nutrients that mix with the soil to help break it down, for example, calcium carbonate is mixed in with the castings, which are now richer in calcium.

In this way, you can consider the worm as a conveyor belt for nutritional enrichment.

Jeff Lowenfells wrote in Teaming with Microbes, worm castings increase soil nutrition as follows:

  • 7 times richer in phosphate

  • 10 times richer in potash

  • 5 times higher nitrogen

  • 3 times higher in magnesium

  • 1.5 times higher in calcium

Photo of my worm bin

I highly recommend this worm bin set as it comes with everything you need including the worms and food. It's almost 1 year later and I've had no problems with it.

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