1. 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.
2. 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.
3. 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.
4. 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 choices.
5. 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!
6. 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.
7. 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 pests.
8. 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.
9. 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.
10. 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.
11. 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.
12. 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.
13. 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?
14. 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.
15. 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.’
16. 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 house.
17. 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.
18. 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 childhood disease.
19. 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.
20. 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.
Thomas 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. His next book, "