FAQ: About Worm Castings


Q: What are worm castings?

A:  The castings (otherwise known as vermicast) produced by worms are the purest and most perfect form of plant food. In addition to containing unusually high populations of beneficial microorganisms crucial to healthy root systems, castings also naturally aerate the soil, help retain high moisture levels, and release nutrients slowly over time to meet your plant’s needs.

Q:  How are castings produced?

A:  True vermicast, like ours, is produced under controlled conditions.  The worms are feed a mixture of peat moss, grains, and a protein booster then the castings are harvested every 14 days and the process is repeated.

Q:  What results should I expect?

A:  Castings can naturally improve the look and health of your plants, stimulate flowering and fruiting, and produce larger harvests. Studies have shown several types of pests and diseases being eliminated naturally. 

Q: What happens if I use too much?

A: Good News! You can't use too much. They don't burn your plants like other chemical fertilizer, even if not properly watered! You do need to water them to activate them but failure to do so right away will not burn your plants like other chemical fertilizers are known to do.

Q: Do they smell?

A: No, they are odor free!! They have an organic smell, similar to dirt!


Q: What happens if my children or pets get into the castings? 

A: This is the best thing about worm castings, they are safe to use around kids and pets indoors or outdoors. Your children and pets can play in the castings just like they do dirt. The only damage done will be that they will get dirty!

Q:  Why are castings better than good compost?

A:  The belly of an earthworm infuses regular compost with beneficial organisms, while further transforming the nutrients into an odourless form more readily useable by plants. Castings can even be mixed with mulch to give your plants what they've been craving. In nature, animal waste and decaying plant material are worm food, not plant food. Worms are the most natural producers of plant food!

Q:  What benefits can I expect?

A: Worm castings have additional advantages over other soils, including traditional composts. When ordinary compost is placed on the ground to enrich plants, the available nutrients are quickly leached into the soil as soon as rainfall or sprinkler irrigation systems are turned on. Vermicompost provides a time-released benefit, slowly nurturing the plants over a greater length of time.  Worm castings contain plant nutrients encased in mucus membranes secreted by the earthworms. Castings dissolve slowly rather than allowing immediate nutrient leaching. The product has excellent soil structure, porosity, aeration, and water retention capabilities. It can insulate plant roots from extreme temperatures, reduce erosion and help with the control weeds.

Q:  What have experts had to say about worm castings?

A:  “Earthworm castings are the best imaginable potting soil for greenhouses or houseplants, as well as gardening and farming. It will not burn even the most delicate plants and all nutrients are water-soluble, making it an immediate plant food. Earthworm castings, in addition to their use as potting soil, can be used as a planting soil for trees, vegetables, shrubs, and flowers. They may be used as mulch so that the minerals leach directly into the ground when watered. The effects of earthworm castings used in any of these ways are immediately visible. The make plants grow fast and strong. Nematodes and diseases will not ruin gardens or plants if the soil is rich enough for them to grow fast. It is the weak plant in poor soil that is destroyed by nematodes and diseases.”

R.E. Gaddie and D.E. Douglas, Earthworms for Ecology and Profit

Volume I “Scientific Earthworm Farming.” 1975, p.175

“Castings contain: 5 times the available nitrogen, 7 times the available potash and 1 1/2 times more calcium than that found in 15 cm of good top soil. Therefore, castings are supplied with available nutrients. The nutrients are also water soluble and immediately available to plant life. You will find that most potting soils have nutrient life of 2-5 days, where worm castings will last up to 6 times as long as other types of potting soils. You will need 5 times as much potting soil to do the same job as the worm castings. So, in the long run, worm castings are much cheaper and do a much better job. Also, castings hold 2-3 times their weight in water. That means you water less and the pot will stay damper for a longer period. Worm castings will not burn your plants; unlike using any fresh raw manure (cow, horse, etc.) which can burn root systems if it is not applied properly. The advantage of using castings is the manure passes through the worms' digestive system producing rich organic plant food and a slow releasing fertilizer that allows for better growth.”

Kids for Landcare: Wormwatch, Education Department of South Australia, 1992, p. 35.


Vermicompost outperforms any commercial fertilizer I know of." continues [Professor. Clive A.] Edwards, who began his earthworm, research in his native England in the early 1970s before coming to Ohio State. "I think the key factor is microbial activity. Research that I and others have done shows that microbial activity in worm castings is 10 to 20 times higher than in the soil and organic matter that the worm ingests."

Dr. Clive Edwards, in "Worldwide Progress in Vermicomposting" by Gene Logsdon in BioCycle October 1994, p. 63.

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