Earthworm Casting Application Rates

Worm compost or vermicompost is compost primarily produced through the digestive action of worms.  Vermicompost will contain a high concentration of worm castings or worm poo...yes worm manure.  Earthworm castings are water soluble, contain modest amounts of nitrogen, phosphorus, potassium, are rich in calcium and a variety of other micro nutrients.  More importantly, earthworm castings contain a vast array of beneficial microbiology that aid in the decomposition of organic matter and the conversion of nutrients into forms available to plants. "Vermicompost outperforms any commercial fertilizer I know of...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

How much worm casting to apply?

New Garden Soil Preparations:

  • Mix 1”- 4” of Earthworm Castings into the top 4” - 6” of soil prior to planting or in spring as soon as the ground can be worked

Seed Starting: 

  • Add as little as 5% (or up to 15%) worm castings to any potting mix
  • Add 1 part Worm Castings with 3 parts (fertilizer-free) peat or coconut coir based seed starting mix

 Annuals, Vegetables, or Perennials: 

  • Seeding: Line seeding trench, hole, or bed with worm castings
  • Transplanting: Add ½ - 1 cup Earthworm Castings per 4" - 6" planting hole 
  • Established plants: Work 1 - 2 cups into the top 2" - 3” of soil around plant


  • Incorporate 1 - 4 cups or worm castings into the top 2" - 3” of soil each spring

 Potted Plants:

  • Apply 1 - 2 tablespoon for each 2" inches of pot diameter, gently work into soil, and water thoroughly

 DIY Potting Soil:

  • 1 part worm castings
  • 2 parts peat or coco-coir
  • 1 part vermiculite, sand or shell flour (which is like a fine beach sand)

When Applying Mulch:

  • Apply ¼" - ½" Earthworm Castings and cover with mulch

Compost Enhancer: 

  • Broadcast Earthworm Castings throughout each layer as you are building your compost pile and lightly water-in.  This will help to accelerate the composting process by ensuring a diversity of beneficial biology is present throughout each layer of your compost pile.

Compost Tea: Water bi-weekly at normal rates for plants needs

 (Please see our brewing and application guidlines under the Compost Tea tab at the top.)


  • Aerate mixture by whisking/ stirring, or pouring from one bucket to another 2 or more times over the course of 24 hours.
  • For best results actively aerate mixture with a Garden Tea Brewer for 12 - 36 hours.  

Your compost tea should remain aerated until applied as the shelf life can be very short.  You can apply teas with a watering can as a soil drench or a with a pressurized sprayer.

The home brewing of actively aerated compost teas provide a healthy alternative to toxic chemical fertilizers, herbicides, and pesticides.

Foliar Inoculant: (For more information please see our brewing and application guidelines for Compost Teas.)

Additional Compost Tea recipes are available here