Worm Castings | Vermicompost

*** We are no longer selling worm castings. To create your OWN high quality castings, we highly recommend setting up a vermicomposting system with our Composting Worms ***

Why Use Worm Castings (aka “Vermicompost”)?

– Improve soil porosity and moisture holding capacity at the same time

– Stimulate robust root growth and overall plant vigor

– Provide your plants with both readily-available and “slow-release” nutrients

– Add “life” to your soil in the form of a diverse ecosystem of beneficial microbes and micro-invertebrates

– Help your plants resist/overcome attack from plant pathogens and pest organisms.

– Will never burn/harm your plants or the soil ecosystem (unlike inorganic fertilizer salts)

Worm castings (also commonly referred to as “vermicompost” and “vermicast”) is a remarkably rich, all-natural plant growth promoting soil amendment.
Unlike “regular” composts, relatively small amounts can have a positive impact. Academic research has demonstrated that potting soils with percentages of castings as low as 5% (by volume) can still produce significant results (Atiyeh et al. 2001). Moreover, it has been shown time and time again that the beneficial effects of this material goes above and beyond what it provides as a fertilizer. Even when plants are provided with the nutrients required for full growth (via inorganic fertilizers), the addition of castings can still increase their growth substantially (Atiyeh et al. 2001; Arancon et al. 2003; Arancon et al. 2008).

Some of the other scientifically determined benefits of worm castings include invertebrate pest resistance (Arancon et al. 2005; Arancon et al. 2007) and plant pathogen resistance and suppression (Utkhede and Koch, 2004; Jack, 2010).

How to Use Worm Castings

As mentioned above, small amounts of this material can go a long way towards improving the growth and overall health of your plants! Our recommendation is to think of worm castings as something like a “health supplement”/”growth promoter” for your plants (rather than as a typical “compost” or “fertilizer”) – and as such, to apply it on a plant by plant basis, rather than simply adding a large quantity of it to your garden soil (not that this wouldn’t be beneficial – it’s more a matter of diluting the effectiveness unnecessarily).

Planting & Transplanting
Our favorite way to use castings simply involves adding a scoop or two at the bottom of all our planting holes, and then another small amount around the base of the plant once it’s in the ground. This approach alone can really help to boost plant growth, but you may also want small quantities around the base of the plant (ideally, wherever you tend to water) every so often during the growing season as well – especially if you weren’t able to add any in the planting hole.

Castings/Vermicompost Tea

Another great approach is to make “worm castings tea” to spray on your plants (or simply water them with). This can be as easy as putting a couple scoops of castings in a cloth bag and repeatedly dunking in a bucket of aged tap water or rainwater (should be able to provide you with 2 or 3 buckets of good “tea”), or as involved as setting up an actual “brewing” system using an aerator (aquarium air pump works great), and adding various amendments (such as molasses and rock dusts) to “feed” the microbes and create an even more potent liquid plant growth promoter.

Potted Plants
Worm castings work really well when used as a component in potting soil mixes, or simply added to pots with established plants in them. Based on our own experience (and results reported in scientific literature), we recommend using 15%-40% (by volume) castings mixed in with your favorite soil blend. To give your houseplants and (established) container garden plants a boost, simply add a thin layer of castings at the base of the plants just prior to watering every so often.

If you have any questions, please drop us a line!

*** We are no longer selling worm castings. To create your OWN high quality castings, we highly recommend setting up a vermicomposting system with our Composting Worms ***


Arancon, N.Q., Edwards, C.A., Babenko, A., Cannon, J., Galvis, P., Metzger, J.D. 2008. Influences of vermicomposts, produced by earthworms and microorganisms from cattle manure, food waste and paper waste, on the germination, growth and flowering of petunias in the greenhouse. Applied Soil Ecology, 39: 91-99.

Arancon, N.Q., Edwards, C.A., Oliver, T.J., Byrne, R.J., 2007. Suppression of two-spotted spider mite (Tetranychus urticae), mealy bugs (Pseudococcus sp.) and aphid (Myzus persicae) populations and damage by vermicomposts. Crop Protection 26, 26-39.

Arancon, N.Q., Galvis, P. A., Edwards, C.A. 2005. Suppression of insect pest populations and damage to plants by vermicomposts. Bioresource Technology, 96: 1137-1142.

Arancon, N.Q., Lee, S.L., Edwards, C.A., Atiyeh, R. 2003. Effects of humic acids derived from cattle, food and paper-waste vermicomposts on growth of greenhouse plants. Pedobiologia, 47: 741-744.

Atiyeh, R.M., Edwards, C.A., Subler, S., Metzger, J.D. 2001. Pig manure vermicompost as a component of a horticultural bedding plant medium: effects on physicochemical properties and plant growth. Bioresource Technology, 78: 11-20.

Jack, A.L.H. 2010. The suppression of plant pathogens by vermicomposts. in “Vermiculture Technology: Earthworms, Organic Wastes and Environmental Management” Edwards, CA, Arancon, N, and Sherman, R eds. CRC Press Boca Raton, FL 604 p.

Utkhede, R., Koch, C. 2004. Biological treatments to control bacterial canker of greenhouse tomatoes. BioControl, 49: 305-313.