Tips for Producing Low-Allergy Gardens
by Thomas Leo
we plant in our own yards often has a direct effect on our own health and
the health of those near us. A pollen-producing male tree in our own yard
will easily expose us to ten times more pollen than would a similar tree
growing just down the block. This can be compared to second-hand smoke.
Yes, it is possible to inhale some smoke from a person who is smoking a
block or two away from you, but it is hardly the same as someone smoking
right next to you. It is the same with plants. If your own yard is full of
allergenic plants, then you will be exposed most. The greater your
exposure, the greater your chances are of having allergies and (or)
are some tips to avoid allergies and asthma:
Don’t plant any male trees or shrubs. These are often sold as
"seedless" or "fruitless" varieties but they’re
males and they all produce large amounts of allergenic pollen.
Do plant female trees and shrubs. Even though these may be messier than
males, they produce no pollen, and they actually trap and remove pollen
from the air. There is also some very good all-female sod to use for
pollen-free lawns. As an added bonus, these female lawns stay low and
require less frequent mowing.
Plant disease-resistant varieties: mildew, rust, black spot and other
plant diseases all reproduce by spores and these spores cause allergies.
Disease resistant plants won’t get infected as much and the air around
them will be healthier.
Use only trees and shrubs well adapted for your own climate zone. Plants
grown in the wrong zone will often fail to thrive. Because they are not
healthy, they will be magnets for insects. Insect residue,
"honeydew," is a prime host for molds and molds produce
allergenic mold spores. Often native plants will be the healthiest
Be careful with the use of all insecticides, fungicides, and herbicides.
Accidental exposure to all of these chemical pesticides has been shown to
cause breakdowns in the immune system. Sometimes one single heavy exposure
to a pesticide will result in sudden hypersensitivity to pollen, spores,
and to other allergens. This is as true for pets as it is for their
owners. Go organic as much as possible. Make and use compost!
Diversity is good. Don’t plant too much of the same thing in your
landscapes. Use a wide selection of plants. Lack of diversity often causes
over-exposure. Use lots of variety in your gardens.
Wild birds are a big plus because they eat so many insects. Plant fruiting
trees and shrubs to encourage more birds. Suet also attracts many
insect-eating birds. Insect dander causes allergies and birds consume an
incredible amount of aphids, whiteflies, scale, and other invertebrate
Use pollen-free selections whenever possible. There are many hybrids with
highly doubled flowers and in many cases these flowers lack any male,
pollen parts. Formal double chrysanthemums, for example, usually have no
pollen. Another example would be almost all of the erect tuberous
begonias. These have complete female flowers, but their male flowers have
nothing but petals, making them pollen-free.
If you simply must have some high-allergy potential plants in your yard,
just because you love them, then watch where you plant them. Don’t use
any high-allergy plants near bedroom windows or next to patios, well-used
walkways, or by front or back doors. Place the highest allergy plants as
far away from the house as possible and downwind of the house too.
Remember: the closer you are to the high-allergy tree or shrub, the
greater is your exposure.
Know the exact cultivar name of a tree or shrub before you buy it. Don’t
buy any that are not clearly tagged with the correct cultivar (variety)
name and the Latin, scientific name. Compare the exact name of the plant
with its OPALS/TM allergy ranking. With this scale, 1 is least allergenic,
and 10 is the most allergenic. Try to achieve a landscape that averages at
OPALS #5, or below.
If you have a tree or hedge that has high allergy potential and don’t
want to remove it, consider keeping it heavily sheared so that it will
flower less. Boxwood, for example, has allergenic flowers but if pruned
hard each year, it will rarely bloom at all.
Get involved with your own city’s tree and parks departments, and
encourage them to stop planting any more wind-pollinated male trees. There
are thousands of fine choices of street trees that do not cause any
allergies and we should be using these instead. Working together we can
make a healthy difference, and we’ll all breathe better for our efforts.
Some localities have enacted pollen-control ordinances. These prohibit the
sale and planting of the most highly allergenic trees and shrubs. These
ordinances can help save lives and lead to more responsible and more
considerate landscaping. Why not get involved and have such a rule of law
in your own community?
There are a great many very useful female cultivars of Red Maple (Acer
rubrum), such as ‘October Glory’ and ‘Red Sunset.’ These trees
have exceptional fall color and are pollen-free.
Female Junipers (Juniperus spp.) are pollen-free and have beautiful
blue-green berries. Numerous female cultivars are sold, such as ‘Blue
Point,’ ‘Icee Blue,’ and ‘Hollywood Juniper.’
Some trees such as the sycamores and London Plane trees (both Platanus
species) produce fuzz on their leaves and stems. This fuzz can become
airborne and causes skin rash, itching, and irritation of the eyes, throat
and lungs. If you must use them, avoid planting them too close to your
Pets can and do get allergies too. Often the exact same plants that cause
us allergy, will also affect our pets. Dogs and cats in particular may be
allergic to pollen. Animals can’t tell us what bothers them. They need
us to look out for them.
Children are especially susceptible to allergies and asthma. It is crucial
that the shade trees in elementary schools be selected to be as
pollen-free as possible. Asthma is now the number one most common chronic
Older people and especially those in hospitals or retirement homes are
also at increased risk from excessive pollen. Shrubs near windows need to
be allergy-free. Pollen is tiny and can easily pass through even the
tightest window screens.
Trees and shrubs next to any bedroom windows will have a large effect on
the health of the people inside these bedrooms. Poisonous plants such as
Podocarpus or Yews, if they are male, will shed many millions of grains of
airborne pollen. Pollen from the males of these two species is both
allergenic and poisonous.
with the dioecious plants (separate-sexed) only males cause
pollen-allergy, and females because they are pollen free, do not. Some
examples of some of these dioecious plants are: red maple, silver maple,
box elder, holly, willow, aspen, cottonwood, poplar, fringe tree, pepper
tree, carob tree, Osage orange, mulberry, cedar, juniper, Podocarpus,
yews, ash, date palms, and even such common garden plants as asparagus.
Ogren is the author of Allergy-Free Gardening, from Ten Speed
Press. More than 3,000 plants are individually allergy-ranked (OPALSTM) in
this book. Tom does consulting work on landscape plants and allergies for
the USDA, Allegra, county asthma coalitions, arborist and landscape design
associations, and the Canadian and American Lung Associations. He has
appeared on HGTV and The Discovery Channel. He has an MS in
Agriculture/Horticulture and writes for such diverse publications as New
Scientist, Earth Island Journal, Landscape Architecture, American Rose,
Pacific Coast Nurseryman, Alternative Medicine, Women’s Day, and Wild
Ones Journal. Tom can be reached through his Web site at www.allergyfree-gardening.com
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