Red Worm Biology - September 13, 2000
Jeff Schalau, County Director, Agent, Agriculture & Natural Resources
Arizona Cooperative Extension, Yavapai County

In August of 1999, I wrote a column on using worms to make compost or vermicomposting. It had basic information to get started with worm composting. This week's column compliments that column. It is a crash course on worm biology compiled by Gila County Master Gardener Jerry English. In the Payson area, Jerry is fondly known as "The Worm Guy". His worm treatise follows.

Mother nature takes 500 to 1,000 years to produce one inch of topsoil or humus. Earthworms, under a stand of trees where leaves drop and animals stand for shade, can produce on inch of humus in five years! Domesticated Brandlings (Eisenia fetida), or red worms, thriving in numbers of 1,000 to 5,000 per cubic foot, can turn their environment into humus in just on season.

Red worm tunnels aerate the soil and facilitate deep watering. The worm castings are concentrated with trace minerals; forming compost that is 100% water-soluble allowing the nutrients to be taken up directly by plants. A healthy population of red worms also makes it unnecessary to till your garden.

A red worm is white and the size of a snip of thread when it first hatches from the cocoon. It is called a juvenile for the first 60 days of life, or until an egg sack appears. The egg sack is about 1/3 of the way down from the mouth end and surrounds the worm's body. Now an adult, the worm literally crawls out of the cocoon, which forms into a lemon-shaped and colored egg sac. Under ideal conditions, a mature red worm reaches it's peak reproduction at about 90 days when it begins to drop a cocoon about every 7 to 10 days.

Each cocoon can hatch up to 20 worms within about two to three weeks depending on temperature and moisture. Cocoons can also lie dormant in the soil for over two years until temperature and moisture conditions become tolerable for survival.

Worms have no teeth. They can only ingest particles they can swallow and require sand to grind their food similar to a bird. They cannot thrive without some sort of mineral or grit present. Horse manure scooped from a stable will add sand to assist in digestion and provide additional organic material. Otherwise, soil can be added to provide grit.

Each red worm is both male and female, so all worms drop cocoons. If you begin with one pound of worms (1,000 to 5,000 individuals), your population will double every month. In one year, you will have over two million. This is contingent upon optimal environmental conditions: 50 to 70 degree F; moisture the consistency of a wrung-out sponge; plenty of organic matter; and a handful of soil.

Below 50 degrees F, worms begin to slow down. At 40 degrees F, they burrow into the soil to find a more stable temperature. Likewise, above 80 degrees F they burrow deeper to cool down. Conditions that are too dry send them deep into the soil. Conditions too wet cause them to surface for air (they breathe through their skin).

It is not true that when you cut a worm in half, it will grow into two individuals. For this reason, use a spading fork, not a shovel or trowel.

Worms can buffer soil pH (acidity/alkalinity). Worm hatchlings immediately adapt to the pH in their new soil environment. An adult worm can tolerate fresh horse manure but not a drastic change in soil pH. Worms tend to move the pH toward 6.5 over time. This means they can raise the pH of a slightly acid soil or lower the pH of a slightly alkaline soil.

So, if you want to increase the rate and intensity of your compost production, simply add worms. Just remember that worms are only to be used in cool composts. Hot compost will kill the worms.

If you would like a reprint of my vermicomposting column, simply contact or visit the Cooperative Extension office. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at and be sure to include your address and phone number. The Yavapai County Cooperative Extension web site is

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Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr. #C
Prescott, AZ 86305
(928) 445-6590
Last Updated: March 15, 2001
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