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The pollen-trapping power of a lawn

by Thomas Leo Ogren

Thomas Leo OgrenThink twice before you give up your lawn.

Lawns are often blamed for causing allergies but the right lawn is actually a powerful allergy suppressor. The best lawn grasses either do not bloom at all or will not bloom (and produce pollen) if they are regularly mowed. What is little understood or appreciated is that a thick lawn is a very effective pollen trap. Pollen blows about and when it lands on smooth surfaces (cars, cement, roofs, decks, large leaves) it doesn't often stay there for long. The next good breeze to come along picks the pollen up and gets it back into the air.

However, consider what happens when airborne pollen lands on a well-maintained lawn. The lawn is composed of millions of long, slim leaves and the pollen grains fall down between these leaves. When it rains or when the lawn is sprinkled, the pollen grains are pushed further downward, down to the ground level. There the pollen is trapped and remains. An average sized lawn at an ordinary house will trap and remove hundreds of millions of grains of pollen each season. A strong growing lawn will trap and remove far more pollen than it will ever produce itself.

To be fair here, a few types of lawns, such as ordinary common Bermuda grass lawns, can be large producers of allergenic pollen. However, common Bermuda produces much more pollen when it is stressed. When a Bermuda grass lawn is kept well fertilized, regularly mowed, and well watered, even it will produce little pollen.

By the way, there are many wonderful new kinds of Bermuda grass that don t ever produce any pollen. There are also types of other grasses that are separate-sexed, and with these the female lawns are also pollen-free. The bottom line here is this: a good lawn is a thing of beauty; it adds considerably to the quality of the landscape and to the actual property value. A healthy lawn is the safest place for our children to play and where they like to play the most. Our dogs and cats also appreciate a nice lawn. A lawn is an excellent area for trapping rainwater from storms. Rain that falls on a lawn will soak in, not run off to the gutters.

A lush green lawn has powerful cooling qualities and will cut our cooling costs in the heat of the summer. A well-kept lawn will not produce pollen and it will trap millions of grains of allergenic pollen from nearby trees and shrubs. A good lawn is a marvelous thing!

Certain types of lawn mowers may kick up pollen that does land on a lawn. A rear-bagging mower will trap and bag pollen along with the grass clippings. A well-maintained mulching mower will deposit pollen back down below the mower and then it will work its way downward with irrigation. A side-discharge mower, used without a bagger, may kick up some loose pollen and this is not recommended. Push reel mowers bring up little pollen and most power reel mowers are also pollen-safe.

There are some allergenic people though who will react negatively to volatile organic compounds that are released when the blades of grass are cut. People who experience this problem would be wise to get someone else to do the actual mowing.

A few types of grasses are somewhat stiff and prickly and less pleasant to lie on. These grasses may irritate the skin of sensitive people. Bahia grass and some of the types of Zoysia grass will cause this itchiness.

Leaf blowers do in fact kick up a good deal of pollen that may be lying about on cement. If you have allergies it is a good idea to wear a face mask when using a leaf blower. Do not blow towards the direction of your house either. It is always a good idea to close the windows in your house too, before using a leaf blower. Pollen is tiny and can easily pass right through the tightest window screens.

Lastly, I want to reemphasize that the right lawn is a very effective pollen trap. Some years ago I measured this by sprinkling cedar pollen on different surfaces and then testing to see how much of this pollen became airborne. Of all the surfaces we tested (car roofs, shingles, cement, bricks, different ground cover plants, gravel) none was nearly as effective at capturing incoming pollen as a thick lawn.

Thomas Leo Ogren is the author of four published books including Allergy-Free Gardening, and Safe Sex in the Garden, from Ten Speed Press. He does consulting work on landscape plants and allergies for the American Lung Association, county asthma coalitions, Allegra, and landscape and nursery associations. He is currently working on a book on Lawns for AOL Time Warner Books. He can be reached through his web site at:

Allergy-Free Gardening