Of all the critters that can be found in a garden I’m always glad to see a worm. The most obvious benefit comes from their constant tilling of the soil providing aeration and improving the percolation of water throughout the root zone. But having been trained in the scientific method at the University of Arizona I’m also glad to find data that supports my beliefs.
Last fall I received an email from plant pathologist at Cornell University. Ms Allison Jack, a PhD candidate, forwarded studies on the use of vermicompost, also known as worm castings, in disease control and plant growth. While scientific papers can be tedious for the layperson, if you’re interested I’ll gladly forward these studies to you. Just send a request to OzarkAggie@gmail.com and I’ll reply with the articles attached.
Fortunately Allison has published an award-winning video that provides an overview of vermicomposting, and how worm castings provide both a nutritional benefit and disease protection for plants. It’s definitely worth a watch.
Know Your Worms
In the US and Canada over 180 different species of worms have been classified, but here we’ll concentrate on the major types used for composting and those adapted to gardens. The fact is not all worms are equal in their ability to do both.
Eisenia fetida – common name Red Wiggler – are used for composting organic materials like manures, vegetable matter, and cellulosic stock like leaves, cardboard, and paper. They’ve become popular among homeowners intent on recycling kitchen wastes, and can be housed in plastic storage containers. However, the Wiggler is a weakling and can’t penetrate soils, especially the clays we have in the Ozarks. This could be advantage for those who wish to use subterranean beds as the worms will be contained by the soil, though this would still require a lid and proper drainage considering the heavy rains we experience.
Eisenia hortensis - common name European Nightcrawler – has been marketed in the US as the Super Red Worm though some reports indicate that it has not lived up to its promise. Though larger than its cousin, the Red Wiggler, its reproduction rate seems to be slower and produce less castings in direct comparisons by growers. What I can’t say is how it will fair in the garden considering our predominate soil type.
Lumbricus terrestris - common name Canadian Nightcrawler – are better for fishing than composting, and while they do a good job of aerating soils in the north there’s a better choice for the heavy clays in the Ozarks.
Eudrillus eugeniae - common name African Nightcrawler – may be the best worm for composting due to its voracious appetite, though it is sensitive to the cold and can not survive temperatures below 60 degrees due to its tropical origins. But they love the heat and temperatures up to 100 degrees.
Amynthas agrestis (or A. gracilus) – common name Alabama Jumper - really can jump out of your hand, or a bait cup as anglers can attest. Strong with a tough hide the Jumper easily burrows into heavy clay, and consumes leaf materials voraciously. Scientists have raised concerns about its appetite and lack of predators. As it has spread north there’s a concern that it will consume the leaf litter in forests and eventually cause environmental damage. Given their popularity for fishing it’s not likely they will be contained.
Composting with Worms
The worm almost universally recommended for composting is naturally the Red Wiggler. For best results you’ll want your worm bin in a room where temperatures range from 60 to 80 degrees Fahrenheit, and feedstock is moist but not too wet. Just as important is maintaining an acceptable pH in the range of 6.0 to 7.5. So you might consider purchasing a Soil Thermometer (useful for determining the best time to plant in your garden) and some pH test strips at a local pharmacy (since a decent electronic pH meter is around $50).
If you’re keeping the bin indoors plastic tubs or buckets are usually employed with holes drilled for drainage and aeration. Some people recommend using shredded cardboard or paper as a carbon (cellulose) source, but naturally I favor leaves. Table and garden scraps should be ground up or blended because the worms don’t have teeth, and you’ll be inviting odorous bacteria and fungi to populate the bin if you’re just dumping chucks of vegetable mater into the mix.
As I mentioned at the start, my idea is to dig a trench and fill it with leaf mold or compost. If your yard slopes drainage won’t be a problem, and covering it with a Styrofoam insulating board will maintain a temperature consistent with the soil and keep the worms from wandering away.
You’ll find examples throughout the web on various methods, including videos, but if you’re serious about raising worms you might want to get a book like: The Best Place for Garbage: The Essential Guide to Recyling with Composting Worms.
While there are several sources on the web for worms you may be better off finding a local supplier. Here’s a directory with listings by state: Vermiculture directory.
Finally I have admit that given the volume of leaves available and the heavy clay in my garden, the Alabama Jumpers seem like a better solution than the Red Wigglers. So if you’re mulching your garden with leaves (or leaf mold) then it would seem to solve two problems at once – aeration of the soil and increased fertility from worm castings. It’s certainly something to consider.