Earthworms are very beneficial to gardens, helping to aerate the soil as they move around which improves absorption of water, nutrients, and oxygen. Worms also leave something valuable behind as they move through the soil, worm castings.

What are Worm Castings?

Worm castings are the end product of worm digestion, the excrement, and provide an organic fertilizer that is rich in nutrients. Worm castings benefit all types of plants, including flowers, vegetables, herbs, cannabis, and more. Worm castings, also called vermicast, are rich in nitrogen and other nutrients and are safe to use even on seedlings, as it’s difficult to overdo it.

Due to a unique digestive system, worm castings contain many microbes and nutrients that benefit plant growth and contribute to a healthy soil ecosystem. They typically appear to be dark brown or black and bear a resemblance to something like coffee grounds or football-shaped particles.

Some gardeners make their own worm castings in a box or a bin with soil, feeding compost to the worms to create castings. Making your own castings is called vermicomposting or vermiculture. There is no need to start “worm ranching,” however, as most garden stores sell worm-casting fertilizer.

How Worm Casting Fertilizer Improves Plant Health

Farmers have always known that worm castings are good for healthy plant growth, and worm casting fertilizer provides many benefits to cannabis growers. Worm casting fertilizer helps to stimulate growth during the cannabis plant’s vegetative growth stage and also contributes to the production of large, resinous buds. Worm casting fertilizer is shown to improve seed germination rates and help to protect against diseases, particularly those caused by root rot or other root diseases. Worm casting fertilizer also repels pests and pathogens and prevents disease.

Worm casting fertilizer can be used on most plants without causing harm or over-fertilizing and will not burn the plant like some other chemical fertilizers can. Casting fertilizer is applied in the soil or introduced to the side or the top of the soil.

Many Benefits of Worm Casting Fertilizer

Worm casting fertilizer provides many benefits to all types of gardens and contains many nutrients and organic matter that help cannabis plants to thrive. Some of the most important benefits of worm casting fertilizer include:

  • Rich in vital nutrients – worm castings are naturally rich in many nutrients and organic matter similar to other forms of manure that spur healthy growth. Nitrogen is the most prominent nutrient, although worm castings also contain phosphorus, magnesium, manganese, iron, zinc, copper, carbon, and calcium. Because worm castings are not readily available to plants, the risk of overfeeding is minimized.
  • Improve the quality of soil health – healthy soil is the key to growing healthy marijuana plants, and worm castings considerably improve the quality of soil by improving soil aeration, increasing water retention, and boosting microbial soil life.
  • Minimize pests and pathogens – castings feed beneficial microorganisms, fungi, and bacteria to store plant nutrients and minimize pests and pathogens. Worm castings particularly help to prevent root rot and root disease and repel pests such as mealy bugs, aphids, and mites because the castings weaken the protective shells of these insects.
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