Our High Potency Worm Castings are a unique soil amendment made by the Red Wiggler worm. Their robust biology boosts plant-available fertility and activates soil life, increasing plant health and resilience, producing stronger plants and higher yields. Worm castings build soil structure, improve aeration, moisture retention, disease suppression, and create a complex web of microbial life that fosters vibrant soil.


Check-Off-Your Gift-List Special!

Make the holidays a little easier on yourself by purchasing a half-case of Black Dirt Farm's High Potency Worm Castings to give away to all the people on your list. They're awesome!

Save 15% off retail prices! Contains (6) 2-Quart bags. Available for pick up at the Farm or Craftsbury General Store.

What are worm castings?

Short educational video on vermicomposting from Cornell University. Project website with full reports available at: http://cwmi.css.cornell.edu/vermicompost.htm 

As food scraps pass through the worm's digestive system, the decomposing matter is colonized by beneficial microorganisms. The resulting manure known as worm castings, naturally contains concentrated communities of valuable bacteria, fungi, protozoa, growth-promoting hormones, fulvic and humic acids, enzymes and other bioactive substances known to improve germination and plant vigor while increasing available fertility. The worms' mucus secretions provide more nutrition and microbial diversity than is found in most garden composts (thermophylic).

What are worm castings used for?

"Castings play a huge part in our organic operation, and in optimizing harvests - quality is imperative. Black Dirt Farm has consistently provided a superior product to any on the market, potency proven time again with each application, and regularly quantified through lab analysis."
- Brenden Beer, Cultivation Manager, Vermont Patients Alliance

Worm castings can be used to enrich potting mix, rejuvenate houseplants, side-dress vegetables and flowers, turbo-charge transplants, or make compost tea. Blended into potting mix worm castings will promote earlier seed germination and seedling vigor, reducing damping off diseases.  During transplant worm castings will increase plants' rebound to shock, support root growth and cell division, retain moisture in the root zone, and inoculate the root zone with beneficial microorganisms that provide some protection from soil born pathogens. During the growing season castings are a premium side-dress, boosting available nitrogen and other growth-limiting nutrients. A tea can be made with the castings for foliar application to help prevent against foliar diseases.

How our worm castings are made

Black Dirt Farm collects food scraps from businesses, schools, and institutions in the Northeast Kingdom and Lamoille River Valley areas of Vermont. Our compost mix is first fed to our laying hens who forage in our compost piles, contributing their manure and blending action as they scratch about for their meal. What isn’t eaten by the hens is removed from their feeding bin and stacked into windrows (tall triangular piles that maximize passive aeration), in which temperatures reach between 140 and 160°F, inactivating weed seeds and pathogens. After the material has achieved the time and temperature requirements for Organic Certification and the EPA’s Process for the Further Reduction of Pathogens (131°F+ for 15 days with 5 turnings of the material), a portion of that material is removed and fed to our worms. The temperatures achieved in the windrow largely reflect the cumulative body heat produced by the rapidly growing bacterial community in the compost. As a result, the material going into the worm bin is loaded with microorganisms, which the worms will feed on, while the change in management at this point rapidly cools the material and allows for low temperature processing. Nitrogen, a critical plant growth nutrient, among others, is volatized at high temperatures, and this cool temperature processing environment helps to retain more of it in total, and more of it in its most fragile and plant available forms. The food web dynamic that results contributes to the production of a biologically robust finished material that will both stimulate your plants, and help support a soil environment in which disease organisms are less able to establish populations that reach pathogenic levels.

The quality of worm castings is determined by the recipe, which at Black Dirt Farm contains 5 or 6  distinct materials. We have crafted our recipe for nutrient density and the rapid and maximum growth of diverse bacterial and fungal communities within the materials by providing optimum microbial nutrition, food webs, and aerobic conditions. Over the composting process we take great care to ensure nutrient retention and the development of robust biological communities. 


You can buy our product directly from the farm or participating retailers in Vermont. 

Central Vermont

  • Hunger Mountain Coop, Montpelier
  • Guy's Farm & Yard, Montpelier
  • Plainfield Co-op, Plainfield
  • Peak Hydroponic Garden Supplies, Plainfield
  • Pete's Greens, Waterbury
  • True Valley Hardware, Waterbury
  • Buffalo Mountain Coop, Hardwick
  • The Flower Basket, Hardwick
  • The Galaxy Bookstore, Hardwick

Burlington area

  • Guy's Farm & Yard, Williston

Lamoille River Valley

  • Menards Agway, Morrisville
  • Guy's Farm & Yard, Morrisville
  • Riverbend Market, Morrisville
  • Johnson Hardware & Rental, Farm & Yard
  • Marvin's Country Store, Johnson

Northeast Kingdom

  • Willey's Store, Greensboro
  • Craftsbury General Store, Craftsbury
  • Natural Provisions, Saint Johnsbury

If your local store doesn’t carry our product, feel free to put them in touch with us.  If they place an order we’ll send you a complimentary 20 quart bag!

To place an order

To ensure the security of your financial information we place orders the old fashioned way. Contact Jenn at (802) 533-7033 or jenn@blackdirtfarm.com

Pallet sale! 20% off!

Organize with neighbors to purchase a pallet of worm castings and purchase at discount prices! Contact Jenn for more information (802) 533-7033 or email jenn@blackdirtfarm.com

Educational & Academic Resources

For background information on the use and efficacy of worm castings and composts in plant propagation, check out our resources page >