Regional Gardening Reports :: National Gardening Association

In the Garden:
Middle South
April, 2009
Regional Report

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A male fruitless mulberry is one of the plants in my Upstate garden that produces a large amount of pollen.

Pollen-Free Plants Offer Allergy Relief

Spring has sprung in the Middle South, but it's not all good news for my family. Every April, my son, Daniel, suffers with headaches, sore throats, and sinus infections brought on by pollen allergies.

Relief for his troubles might be in sight, however. I've recently learned that his ailments could be triggered by trees and shrubs planted just outside his bedroom window and that dramatic improvement might be obtained by simply removing and replacing the offending plants.

According to Thomas Ogren, author of Allergy-Free Gardening, a yard filled with pollen-producing plants can be as dangerous as secondhand smoke, and the closer you are to the source, the more you suffer.

Like my family, Ogren has first-hand experience with the problems and frustrations of pollen allergies. His wife, his mother, and his sisters all suffer from asthma and hay fever. Pollen-free landscaping is not just a passing fad for his loved ones. As he says, it's a matter of life and breath.

After more than twenty years of research, Ogren has created a plant allergy scale called OPALS (Ogren Plant Allergy Scale), that rates the allergy potential of plants on a scale from one to ten, with the worst plants rated as a ten.

As Ogren explains, some plants are dioecious, meaning they are separate-sexed -- either male or female. Only male plants produce pollen and trigger allergies, asthma, and other illnesses. Female plants never produce pollen, but they trap and use pollen to make fruit and/or seed which may eventually litter the landscape.

Because female plants are considered messier, landscapers have developed a preference for male plants. This is especially true in areas requiring low-maintenance landscapes, such as schools and hospitals.

Some of the dioecious plants commonly found in the Middle South include red maple, holly, willow, poplar, mulberry, cedar, juniper, and yew. Male selections of these trees and shrubs are some of the worst allergen offenders, producing great quantities of pollen and rating at the high end of the OPALS scale.

For low-allergy gardens, choose female selections of dioecious plants. Or, consider other types of plants that produce little or no pollen, including cultivars that are permanently juvenile (never produce flowers), intergeneric hybrids (male sterile crosses between different genera), and formal double hybrids (with tightly packed petals).

If pollen presents a health issue for you or your family members, here are additional suggestions for a low-allergy landscape:

-- Trees and shrubs sold as "seedless" or "fruitless" varieties should be avoided, as they produce copious amounts of allergenic pollen.

-- Choose disease-resistant varieties of plants. Mildew, rust, black spot, and other plant diseases reproduce by spores which also cause allergies.

-- Go organic whenever possible. Exposure to insecticides, fungicides, and herbicides weakens the immune system and can result in hypersensitivity to pollen, spores, and other allergens.

-- Use a wide selection of plants in the landscape to prevent over-exposure to any single allergen.

-- If you must include high-allergy plants in your garden, relegate them to the far reaches of the landscape and never plant them near windows or doors.

-- Some trees and shrubs with high allergy potential, like boxwood, will produce less pollen when kept heavily sheared.

For additional information, visit Ogren's Web site at

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