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Anne K Moore
Photograph of Alstroemeria by Ildiko Lazlo


Years ago I learned, from Rachel Carson’s “Silent Spring”, to look at labels with new eyes rather than just dumping anything onto my plants or into my yard and ultimately into the environment. Tom Ogren has brought along a new red-eye opener, The Allergy Fighting Garden, which could be just as significant in its usefulness, effectively starting a conversation helpful to everyone suffering from air-borne allergies.

Tom’s allergy scale, from one to ten, is one of the most significant and useful parts of the book. You can find it near the back of the book where there is an A-Z listing with Tom’s own developed ranking for the listed plants. He gives zonal and growing information as well as their allergy rating. Pictures enhance these encyclopedic type entries.

Tom does caution you to read the whole entry for the plant you are interested in growing. For instance, the tree species of Wisteria found in the U.S. have an allergy rating of 4, not too bad, but since it is in the legume family, someone with a peanut allergy could be more sensitive. All of the species, as well, have long pods filled with poisonous seeds. Dogs can become sick if they eat the big hard seeds. This is very useful information for the home gardener.

Another section contains the explanation of dioecious plants (separate male and female plants) with the “why” male plants are not a good fit for the landscape, even though they produce no messy fruits or seeds for the gardener/yardener to clean up. They produce air-borne pollen, impossible to clean up in the open air.

How, you might wonder, will keeping allergy-causing plants out of my yard benefit my allergies? Pollen will just blow in from down the street. Tom explains, “With pollen allergies, everything is in the actual dose received.” He continues, “The closer you are to the source of the pollen, the greater your exposure will be.”

Tom suggests planting an allergy-free windbreak on the side of your yard that receives most of the wind. These tall trees and shorter shrubs will trap most of the pollen from your neighbors. He goes on to suggest what to plant on this windward side of your property.

Another hugely interesting and helpful part of The Allergy Fighting Garden deals with how to determine the sex of a plant. Now this is something I bet you never thought you could use. After reading Tom’s book, finding female plants at the garden centers is now a priority. He has a list with characteristics to look for.

Something I had not given much thought to, OK I hadn’t given any thought to, is the fact that insect infestations on plants promote mold and mold releases spores that are allergens. Remove the infestations and no more mold spores.

Information you can use is listed in a horticultural terms glossary and a listing of useful websites along with charts showing a pollen-calendar-listing by trees, shrubs, and grasses rounds out the book.

This is an important volume for amateurs and professionals alike. All the tools you need to plant an allergy-free landscape are included in The Allergy Fighting Garden.

Be sure to read Thomas Ogren’s article in this E-newsletter, Allergy Fighting Gardens.

The Allergy-Fighting Garden can be purchased from,,, or any online bookseller of your choice.
Reprinted with permission from The Allergy-Fighting Garden by Thomas Leo Ogren, copyright (c) 2015. Published by Ten Speed Press, a division of Penguin Random House, Inc. Photography (c) 2015

ABOUT THOMAS LEO OGREN: Tom has a Master’s degree in agricultural science. He is a horticulturist and allergy researcher. The system of allergy ranking, on a scale from 1-10, called OPALS, was developed by Ogren and is now used by the United States Department of Agriculture. He lives in San Luis Obispo, California.

Posted March 13, 2015

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