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New Book Contains Information on Allergy Potential in Gardens
by Peter Prakke
September 26, 2017

Horticulturist Peter Prakke of Ancaster, Ont., has made it his mission to promote landscapes of allergy-friendly plantings to ease the discomfort of individuals with allergies, asthma, and other respiratory challenges.

“A runny or stuffy nose, red eyes, sneezing or wheezing caused by allergies are a fact of life for millions of allergy sufferers,” writes Peter in his new book, The Veterans Gardening Guide expected to be released in early 2018. “What we plant in the garden has a direct effect on our health and the health of those near us.” Peter was instrumental in changing the direction of the Hamilton-Wentworth District School Board and the Hamilton-Wentworth Catholic District School Board in Hamilton, Ontario Canada to use the Ogren Plant Allergy Scale (OPALS).

The scale created by Thomas Ogren in his 2000 book, Allergy-Free Gardening, measures the allergy potential of all garden and landscape plants. The United States Department of Agriculture and the American Lung Association use the scale to make improved landscaping decisions.

“A pollen-producing male tree will easily expose you to ten times more pollen than a similar tree growing down the neighbourhood block. This can be compared to second-hand smoke,” says Peter. He goes on to say that emergency departments are seeing a stark increase in the number of children admitted during the pollen season.

“Pollen levels in the city and urban areas are high and increasing due to global warming and the interaction with air pollution. The perfect solution is to limit the number of male plantings, and focus our attention on female plants that trap pollen and clean the air of particles and shed no pollen,” says Peter.

According to Thomas Ogren, pollen isn’t always that easy to see, nor is it bright yellow. It can be white, grey, green, brown, red, and even purple. Experienced gardeners, or budding gardeners will discover a new world in The Veterans Gardening Guide for those suffering from allergies, asthma and COPD. Readers will find that male and female plants of separate-sexed species behave differently. Female plants produce fruit and seeds, and male plants produce pollen, though not year-round.

Peter says that peak pollen times depend on the plant, weather and your location. “I am frequently asked by amateur gardeners and gardening professionals if it’s possible to plant for allergies and asthma. Yes, and it’s quite easy.”

Peter lists ten tips to remember when planting a garden.

1. Avoid planting any male shrubs or trees. These are sold as fruitless or seedless varieties, but they are classified as males and produce large amounts of allergenic pollen.

2. Plant female shrubs and trees. Although female species may be messier than males, they produce no pollen and trap or remove pollen and particulates from the air.

3. Plant disease-resistant varieties which won’t become infected, and the air around them will be healthier.

4. Use only shrubs and trees adapted to your climate zone. Often native plants are the healthiest choices, but native plants can also cause allergies.

5. Don’t plant too many of the same varieties. Diversity is good. Use a wide selection of asthma- and allergy-friendly plants.

6. Attracting birds to your garden is a big plus because they eat many insects. Insect dander causes allergies and birds consume an incredible number of aphids, scale, whiteflies and other pests.

7. Know the exact cultivar name of the shrub or tree before you purchase. Plants that are clearly tagged with the correct cultivar and scientific name will determine the allergen ranking.

8. Use pollen-free selections whenever possible. Double chrysanthemums usually have no pollen. Almost all of the erect tuberous begonias have female flowers, making them pollen-free.

9. If you must have some high-allergy potential plants in your garden, because “you like them so much,” plant downwind and as far away from the house as possible.

10. If you have a tree or hedge that has high-allergy potential, and you don’t want to remove it, consider keeping it sheared so that it will produce fewer flowers. For example, the boxwood has allergenic flowers, but if given a yearly hard prune, it will rarely bloom.

According to Thomas Ogren, a plant need not necessarily be female to be allergy-free, and a good OPALS ranking is always an indication of low potential to cause allergy or asthma. “If you are able to purchase a plant that has an actual OPALS ranking (1 to 10) tag on it, then that is something you can trust.

As Peter explains, each OPALS ranking. indicates a different allergy reaction.

1 to 3: Very low potential for causing allergies. For example, the red sunset maple (Acer rubrum) is 1 on the OPALS ranking, meaning the least allergenic.

4 to 6: Moderate potential to cause pollen allergies, exacerbated by over-use of the same plant throughout the garden. Most pine trees (Pinus spp.) will be ranked at 4 to 5, as they will cause some allergies.

7 to 8: High potential to cause allergies; plant as few as possible. The sycamore (Platanus spp.) has an OPALS ranking of 8 and can cause quite a few allergy problems.

9 to 10: Extremely high potential to cause allergies, and should be replaced with less allergenic species. The worst plants on the OPALS ranking can often cause both hay fever and asthma. They may also trigger skin rashes. ‘Autumn Spire,’ a male cultivar of red maples, has far more potential for allergy and is ranked at 9.

Peter was born and educated in the village of Eibergen, in the eastern part of Holland, that was under German occupation in World War II. During the battle to liberate the village, two British soldiers died, and their graves are in the village cemetery. With the passing of time, Peter never forgot the sacrifice made by the soldiers and created his book as a tribute to them and all veterans representing their country during war and conflicts.

The Veterans Gardening Guide lists hundreds of plants with each showing its OPALS ranking. Watch your CHTA Newsletter

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