Pure Earthworm Castings
Soil Amendment Worm Castings Label
Pure Earthworm Castings Soil Amendment
Earthworms in Soil
Bulk Bag of Worm Castings

Pure Earthworm Castings | RMBA

Regular price$22.95
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For a pure, fresh, organic way to stimulate soil health and encourage plant growth, consider ever-magical Rocky Mountain BioAg® Pure Earthworm Castings. These castings are the rich, nutrient-dense excrements of night crawler worms that are fed organic materials, minerals, and trace elements key to soil health. This “super humus” is known as a natural soil conditioner because it does so much to help your plants.

Earthworm castings contain high concentrations of nitrogen, phosphorus, and potassium, the three most essential nutrients for plant health. No matter whether you’re focused on fruit trees, vegetable gardens, or rows of beautiful flowers, earthworm castings are proven to help every soil type in tons of different conditions. 

Pure Earthworm Castings from Rocky Mountain BioAg® are the obvious choice for all who seek to use organic, environmentally friendly gardening practices. Earthworm castings come straight from the earth, so you never have to worry about harming plants, animals, or the environment. Sustainable farming and fertilizing have never been easier than with Pure Earthworm Castings from Rocky Mountain BioAg®!


  • All-natural soil amendment made in the USA
  • Perfect for soil mixes, top dressing, or compost teas
  • Can be used on a variety of plants
  • Improves water retention and soil structure

    Application Rates

    Base Potting Soil:
    Mix 15-25% (1.125 - 1.875 Gallons) per cubic foot base potting soil.
    1 dry cubic foot = 6.50 Gallons
    1 wet cubic foot = 7.50 Gallons (used in above calculation)

    Top-Dress Established Plants:
    1 Tablespoon per inch of pot size. Apply as needed throughout the plants life.

    Compost Piles:
    Spread a thin layer of pure earthworm castings between each new layer of material to be composted.

    Vegetables and Annual Flowers:
    Line bottom and sides of plant hole and seed furrows with 1" - 2" of pure earthworm castings. Set seeds or plants in place and cover with soil. Side dress during growing season at a rate of ½ cup per plant or 1 cup per linear foot row once every 2 months.

    Work ½ cup into the soil above their root zone taking care not to damage shallow roots. Apply in spring, early summer and early fall.

    Roses, Trees, Shrubs and Berries New or Freshly Transplanted:
    Mix 1 part pure earthworm castings to 3 parts soil. Surround newly dug hole with mixture. Spread roots over a mound of the mix in the hole and cover.

    Roses Established:
    Mix 4 cups of pure earthworm castings into the soil 2" - 3" below the surface for each plant.

    Starter or Grow-Ins Turf Grass:
    Apply 100 lbs. per 1,000 sq. feet. Till or rake into the top 2” – 4” after surface spreading mix in grass seed and water well.

    Established Turf Grass:
    Apply as a top dressing for fairways, rough, lawns, greens, landscapes, or on any established grass. Apply 100 lbs. per 1,000 square feet.

    Compost Tea

    2 Cups per 5 gallons of water, aerate with the proper size air pump, brew for 24 - 34 hours. Best brew time depending on conditions is usually 30 hours.


    Use Microbe Life Hydro / Quantum Growth microbial inoculants for superior results and apply when the time is right for you! Quantum Organic Light, Quantum Growth Organic VSC and Quantum Organic Total will save you time and money completely the need to brew compost teas. The Quantum Growth Series provides pure biological strains allowing you to perform controlled biological inoculation with replicated results time and time again! No waiting on brewing, just mix the probiotics with clean water your favorite plant amendments / foods and soil drench or foliar apply immediately!


    • 2 Gallon Bag and .4 Cubic Foot Box

    *Contact RMBA for pricing on bulk worm castings*

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    Biological... Beyond Organic®

    Organic is just the start

    RMBA is committed to provide natural and organic products that support healthy soils. Even if a product is not listed as 'organic' you can rest assured that it will help, not hurt your soil.

    Don't take our word for it


    This has been the best pumice i have ever used!!! Besides the great customer service (*****)

    Ricardo S

    McAllen, TX


    Rocky Mountain BioAg has the best customer service! Prompt delivery and product support. Thanks !

    Joe B

    South Kingstown, RI


    I have a greenhouse that unfortunately does not get the ideal sunlight due to its location on the north side of my home. I have been using Rocky Mountain BioAg’s Quantum Growth Organic Total for over a year and have seen a dramatic increase in plant growth and vegetable yield compared to past years. Highly recommend the product.

    Jack C

    Sarasota, FL


    Excellent customer service, quick response, fast turnover and shipment of merchandise and product was exactly what was described on website and what I wanted. Great Company!

    Jessica S

    Harrisonburg, VA