Updated: Oct 15, 2020
What are worm castings?
Worm castings also known as vermicast is basically earthworm poo. A superfood organic fertilizer made by worms! Worm castings can be used for both indoor and outdoor gardening, and can even be added to compost piles.
Worms digest organic materials and refine nutrients like, minerals and trace elements, to their most usable forms with a neutral ph of 7.0. In addition to containing low levels of essential nutrients, the castings also include iron. The process of making worms castings is called vermicomposting or vermiculture.
Benefits of worm castings
Adding worm castings helps aerates soil, adds beneficial microbes, improves the overall structure of the soil, aids in plant growth and helps fight off diseases.
The castings make the soil more absorbent, allowing moisture to be more available to plants, while helping to prevent the soil from completely drying out.
Worm castings also contain humic acid which aids the plant with nutrient absorption.
Research done at the Ohio State University Soil Ecology lab reports that adding worm castings to soil enhances seed germination, plant growth, flowers and fruit production. The castings also curbed certain diseases like root and crown rots, and wilt disease. Vermicast also inhibited mites, aphids, and mealybugs.
A 2011 Cornell University Dept. of Plant Pathology & Plant Microbe Biology demonstrated suppressed diseases in seedlings with the use of worm castings. The castings also naturally degraded the protective covering of insect pests, making it good for pest control. It also regulated plant nutrient release by stimulating the nutrient cycle from soil to plants.
How to apply
Adding worm castings directly as a top or side amendment won't burn the plant due to the high nitrogen content (4-5% more N than average garden soil) because of it's slow release. The slow release is due to the mucus the worms secrete as they digest.
Follow the manufacturers instructions on how to apply. We have been using Wiggle Worms Soil Builder, and they have detailed instructions on their website and even a worm tea recipe that you can make from their castings!
Make you own vermicast
Vermicomposting is now a popular method of composting. By using your own kitchen scraps you can make your own powerful soil amendment.
For the bedding, shredded newspaper can be used, or even coco coir, straw, wood chips and sand. Add enough kitchen scraps to feed thousands of worms. Kitchen scraps include fruit and vegetable peels, grains, breads, cereals, coffee grounds, unbleached coffee filters and tea bags. Do not add meat, dairy products or cooking oils, to compost those things you need a Bokashi composting system. Never add pet waste to the worm bin.
Check the manufacturers recommendations for the amount of worms to add. Usually the ratio is 1lb of worms to 1lb of organic material.