Below is a great article by Denise Hodgins that provides an introduction to using diatomaceous earth in your garden. Thanks Denise for bringing attention to pesticide free gardening methods!
GROWING CONCERNS: Diatomaceous Earth keeps pests out of the garden without using pesticides
By Denise Hodgins, Special to QMI Agency
People looking for an organic, non-pesticide way to keep pests from their garden often get good results using diatomaceous earth.
Diatomaceous earth is a powder made of 100% organic ground fossils of diatoms that came from fresh water. It is actually a geological deposit made up of the fossilized skeletons of marine and freshwater organisms (diatoms and algae).
These skeletons are composed of hydrated amorphous silica. When crushed, they break up into microscopic bits. The interesting property is that these microscopic bits are razor sharp like so many bits of jagged glass. To humans and animals they feel like talcum powder. But to many pests, including ants, snails and cockroaches, they’re deadly.
So how does diatomaceous earth work?
Insects pick up the microscopic bits of diatomaceous earth on the small hairs of their body. The jagged edges scratch at their bodies and pierce the protective waxy layers. They also eat some of it. The insects lose moisture, stop eating and die. The powder also repels the “smarter” insects and they won’t go near it.
How fast does diatomaceous earth work?
It can take several days to kill a pest that has been exposed to this product. It is not a fast contact kill such as insecticidal soap.
Though soaps and other fast-contact kill sprays have no residual action (you have to hit the insect to kill it), diatomaceous earth is a perfect long-term residual organic insecticide. As long it is in the area, it is effective and continues working.
Is diatomaceous earth safe for humans and pets?
Yes, skin contact is no problem at all. It feels like talcum powder. The only caution is that you don’t want to breathe the dust while applying it to the garden or house area. Wearing of dust masks while applying diatomaceous earth is a recommended safe gardening practice.
What insects does diatomaceous earth control?
Darn near any insect will be killed by this product including beneficial insects. This is why we don’t spread it everywhere but are selective in how we apply it.
It will control all soft-bodied garden insects, such as snails and slugs, and earwigs.
In houses, diatomaceous earth is used to stop the entry of certain insects such as earwigs, ants and cockroaches, and to control these and others (such as fleas) in food cupboards, carpets, basements, attics and pet bedding. You can put the powder in cracks and corners for better control.
It can be used to treat the roots of new transplants and the barks of trees to stop chewing insects. Diatomaceous earth will not stop mice or rabbits, but if these animals get it on their fur, they will not get fleas. Control for fleas on our pets can be done by dusting the animal and the bedding area.
How to best use diatomaceous earth:
Make a shaker out of an old coffee can and an extra lid to make application a little easier, and reduce waste. Punch holes in the bottom of the can with a nail. Cover this end of the can with your extra lid. Fill the can and cover the top with your other lid. Place a lid from a second can on the other end for storage. Remove the lid covering the holes when you are ready to sprinkle diatomaceous earth on your garden.
Apply the diatomaceous earth when you don’t expect rain in the next few days. If it does rain, reapply the powder as soon as the plants and ground dry out.
Dust plants with a layer of the diatomaceous earth. In addition, coat the ground around the plants. Look for anthills and other insect nests. Apply the powder directly to these nests.
I’ve had great success using diatomaceous earth to control earwigs and ants both in the garden and home. Remember not all bugs are bad, so use your controls wisely.
Denise Hodgins holds an Ontario diploma in horticulture. Growing Concerns is produced by Van Horik’s Greenhouses and Heritage Country Gardens. Send your gardening questions to Home, c/o The London Free Press, P.O. Box 2280, 369 York St., London, Ont., N6A 4G1, fax (519) 667-4528 or e-mail john.ryan@sunmedia.ca and we’ll try to respond in future columns.