The Wonders Of Worm Poop

By night, Ned Selfe (pronounced self) is a pedal steel guitar and dobro musician who earned two Grammy nominations for Best New Artist and Best Engineered Recording. By day, Selfe owns and operates a vermaculture business in Kalaheo.

Ten years ago, Selfe attended a workshop on worm composting sponsored by the Kauai County Recycling Office. The presentation, by Joy of Worms on Maui, filled Selfe with such inspiration, he left with a box of demonstration worms.

Today, Wiki Wiki Worm Ranch grows and sells worms and worm byproducts. Vermicompost, also called worm manure, worm castings or vermicast, looks like soil and is used as plant food. Leachate, also called liquid worm castings, is used as foliar spray.

Making worm castings at home produces a cheap, all-natural fertilizer, while diverting waste from the landfill.


Vermicomposting is a process in which earthworms and other microorganisms consume and digest organic waste, such as kitchen scraps. Earthworm digestion mixes, conditions, and inoculates residues and nutrients are encased in mucus membranes that are secreted. Worm waste is collected in liquid and solid forms and used as a highly beneficial and cost-effective plant food.

Liquid castings make an excellent foliar spray. “Worms are mucus-y,” explains Selfe. “When you spray leachate on the leaves, it builds up a film which repels bugs and protects the plant from mold, mildew and spores. My wife loves using it on her orchids!”

Solid castings can be used as a soil amendment or used to make worm tea.

When compared to 6 inches of good topsoil, worm castings have five times the available nitrogen, seven times the available potash and 1.5 times more calcium. Worm castings contain a high percentage of humus, which helps soil particles form clusters, creating air channels and improving water retention. Humus prevents harmful plant pathogens, fungi, nematodes and bacteria.

Worm castings are biologically active and contain thousands of beneficial bacteria and enzymes. Nutrients in worm castings last up to six times longer than other types of potting soil.

Castings hold two to three times their weight in water, do not burn plants, slowly release nutrients, are water soluble and are an immediate plant food. All of this makes plants grow fast and strong.

State law restricts importing potentially harmful organisms. It is illegal to import worms into the state, so do not mail-order worms from out-of-state suppliers. Fines for violating quarantine restrictions can be as much as $25,000.

Castings can be used in greenhouses, pots and houseplants as well as gardens and farms, and are used as planting soil for trees, shrubs, vegetables and flowers.

“The county is desperate to get anything they can out of the waste stream,” explains Selfe. “Allison Fraley of the County of Kauai Solid Waste Division told me that in one day, 240 tons of waste is produced on Kauai. If we divert one pound, per person, per day from that stream by using a worm bin, that’s 20 tons!”

Marta Lane is a Kauai-based food writer. For more information, visit