By Dr. Leonard Perry
If you're like one in six Americans, you get some sort of seasonal allergies each year. If you're a gardener, this doesn't mean you have to suffer. You don't have to give up gardening during part of the season, or have to convert your landscape into silk flowers, gravel beds, and garden gnomes or plastic flamingos! Changing some gardening practices, or choice of plants, may be all that's needed to lessen the symptoms.
Most people see the yellow pollen on their car in spring or summer and think, that's it! That's what's causing my allergies. This relatively big, showy pollen you see from trees and flowers really isn't the culprit. It's the microscopic pollen you don't see that causes allergies.
This can be from deciduous trees in the spring, such as oak, elm, birch, maple, ash, alder, some pines, box elder, and willow. The hardwoods, in particular, are the culprits. Other trees, especially in warmer parts of the country (whether you live there, or travel to visit gardens) include cedar, cottonwood, hickory, mulberry, olive, palm, and pecan.
Trees with showy flowers, just as with flowers, tend to be pollinated by bees, butterflies, or other insects, so have larger pollen, which doesn't blow around and cause allergies. Examples of low or no allergen trees include many of the fruit trees such as apples, crabapples, cherries, pears, plums, and others, such as dogwoods and magnolias, in warmer climates.
Shrubs to avoid include many junipers, and in warmer climates, cypress and privet. Hydrangea, azalea, and viburnum are okay, as are the boxwood and hibiscus in warmer climates.
In his recent book Allergy-free Gardening, author Thomas Ogren attributes many of our allergies to recent changes in our landscapes, particularly the planting of male trees and shrubs. Gardeners often do this to avoid messy fruit from female trees, but end up, as a result, with more pollen. He even advocates sex changes in trees, grafting a female top onto existing trunks of male trees.
Ogren has developed, and advocates using, the Ogren Plant Allergy Scale. It rates plants from 1 (low) to 10 (high) for pollen and allergies and is useful in determining what plants to buy if allergies are a concern.
As with the woody plants, those herbaceous plants with showy flowers are generally okay and include daffodils, tulips, daisies, geraniums, impatiens, iris, lilies, pansies, petunias, roses, sunflowers, zinnias, and many more. Some flowers with strong scents also may aggravate allergies, even if they normally have larger pollen.
Of course, weeds are often the most allergenic plants. One ragweed plant can produce up to one billion pollen grains, and they have been tracked over 400 miles away! Others include pigweed and Russian thistle. A couple perennials are falsely accused of causing allergies, as they bloom at the same time as ragweed. Some people see the goldenrod and Helen's flower (alias "sneezeweed") and think these are the enemy, while it is really the ragweed lurking in the background.
For more information, consult Allergy-free Gardening by Thomas Ogren. Websites with useful information include those of the American Lung Association, the American Academy of Allergy, Asthma and Immunology, and the Intellicast weather site, among others. These and others can be found through a search on an Internet search engine such as Google.