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Beginners Guide: Worm Castings

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Worm castings contain five times more nitrogen, seven times more phosphorus and 11 times more potassium than ordinary soil.

Worm castings or vermicast are both just another way to say worm manure. It turns out this stuff is awesome for your soil and plants. Growers and gardeners all over are discovering how well their plants respond to worm castings and the many ways it improves their gardens. After reading this article if you haven’t discovered worm castings already I bet you will be headed out to buy some.

What makes worm castings so great?

Worm castings are biologically different from soil and compost. It has a much higher concentration of humus. Humus might be the most important part of your soil. Humus is the black or dark brown part of your soil that remains after most of the organic material breaks down. When humus is in the soil air and water can move more freely. I also think of humus as a big sponge for your soil. It holds up to 90% of its weight in water so nutrients and water are not washed through the root zone. This helps create a nutrient soup the roots can feast on for longer and saves water

What are some of the other benefits of worm castings?

  • Worm castings reduce the acid-forming carbon in the soil, and increase the nitrogen levels to a state the plant can easily use.
  • Worm castings take up toxins and harmful fungi and bacteria from the soil.
  • For those of us who are enthusiastic gardeners and tend to fertilize too much, worm casting will never burn your plants or soil.
  • Worm castings contain millions of beneficial microorganisms that break organic matter down into nutrient forms that are easily and immediately absorbed by plants.
  • Earthworms produce an enzyme called chitinase. This is an enzyme that breaks down the exoskeleton of insects. This is a natural repellent for many insects. Worm casting reduce and can eliminate stubborn sap-suckers like aphids, thrips, whiteflies, mealy bugs, and mites.
  • No bad smell! Worm castings have a dark, rich color, with a slightly earthy smell when moist, and has a soft, velvety feel.
  • Worm Castings are packed with minerals that are essential for plant growth, such as concentrated nitrates, phosphorus, magnesium, potassium and calcium. It also contains manganese, copper, zinc, cobalt, borax, iron, carbon and nitrogen.

I’m sold – Where can I buy it?

The good news it worm castings are sold almost everywhere you buy garden products. I have also had luck finding local producers selling bags direct at a reasonable price that is fresh and high quality. Seriously you can try craigslist.

What if I want to make it myself?

For anyone who has composted before, establishing a process to produce worm castings will be easy. For those of you who have not tried this before, here is a great article showing you step by step how to do this process from the University of Nebraska. It also provides information with how to keep the process going.

I am always excited to share information about how to make our plants thrive while saving water. Worm castings do exactly that for us. This is a simple and easy way to improve our gardens, landscapes or small farms. If you have some experience with worm castings I’m sure our readers would like to hear about it in the comments below. If you enjoyed this article please subscribe or follow me on twitter @H2otrends.



  • Kevin ,

    Thank you for a great article, one can never read enough on the subject of vermiculture!

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