If you know you have allergies, but don’t know to which plants or trees, visit an allergist for testing. Once your specific allergies have been diagnosed, you’ll know what to eliminate from your garden plans. Next, research the allergenicity of plants. “Read everything on the subject you can find,” advises Thomas Leo Ogren, author of the definitive Allergy-Free Gardening and an expert on horticulture and allergies. “Go on the Internet and read articles, read books, learn as much as possible.”

There are several factors that determine how much a given plant will affect someone predisposed to pollen allergy. These include the sex of the plant, size, shape and colour of the flower, how the plant is pollinated (by wind or insects) and what the pollen itself is like.

Pollen and Pollination

The size and shape of a plant’s pollen can dictate its allergenicity. So does its means of getting from one plant to another. Wind pollination requires light pollen – and lots of it – that can travel great distances. This is the troublesome kind because it is abundant, easily inhaled and likely to cause allergic reactions. Flowers that depend on bees, wasps, butterflies, moths and beetles for collection and dispersal of pollen tend to produce heavy, sticky grains that are somewhat airborne. A good rule is to avoid all wind-pollinated plants, unless there are female versions available.

Plant Gender

Head to plants with bigger, brighter blooms. “Go for flowers with bright colours and as many petals as possible,” says Ogren. The showier flowers tend to be insect pollinated, and the shape of the bloom will also play a part. If the pollen is buried deep inside the flower, it will be less likely to blow away on the wind and into your nose. Stalwart examples of low-pollen summer flowers include pansies, violets, hydrangeas, gladiolus and fucshia, to name a few.

Be careful with heavily scented blooms, which can trigger attacks in asthmatics. This is especially important when choosing roses, which are often prized for their scent as much as their beauty.

Annuals are a great way to add yard colour, and many aren’t triggers for allergies unless planted in large clusters. Some of the better choices are: impatiens, petunias, sweet pea and foxglove.

Shrubs, Trees

“I would not buy and plant anything that lives a long time, any tree or shrub, unless I had a very good idea of what it’s allergy potential was,” says Ogren. “Don’t buy any that are seedless, fruitless or podless since they are probably males and will make lots of pollen.” Look for shrubs and trees with berries or fruit rather than flowers – they’ll be female.

Grass

We love our lush lawns, but grass is the most common, persistent allergy offender. In fact, it can cause reactions even if it’s not the allergen because pollen, dust, mould, and insects and their droppings get trapped in the lawn, and then disturbed when you mow. The best option is to avoid laying sod altogether. Stylish, modern gardens are often a mix of stone pathways and flower beds.

If you must have a patch of green, weekly mowing is key. This will keep the grass from flowering and producing pollen, and provide less of a harbour for other allergens. Using a push mower also disturbs allergens less. Be sure to clean up clippings promptly to avoid mould growth. Better yet, have a non-allergic person mow the lawn.

Mold Allergens

“The worst molds in the garden are caused by insects on buggy plants,” says Ogren. Unhealthy plants should be replaced, and the others fertilized regularly to keep them healthy. Rake up leaves in the fall and avoid overwatering, which can create a perfect damp environment for mold to flourish.

The Uncontrollable

Whether it’s a towering tree you can’t cut down, pollen floating in from miles away or what your neighbors have planted next door, there will be some things beyond your control. But, there is much about your outdoor space that you can determine. With some research and planning, you, too, can get digging.

Next Page: Allergy-Friendly Plants to Look For

We spend up to 90 per cent of our time indoors, sealed tightly into our homes, trying to prevent costly energy loss and escape the chill of winter. But there’s a big looming cloud over the cozy picture. It’s inside air pollution.

The U.S. Environmental Agency labels indoor air one of the top five environmental health risks. Pollutants known as volatile organic compounds or VOCs are especially irritating to people with asthma or chemical sensitivities. And these gases are everywhere: they’re given off by new furniture, adhesives used in carpeting and cupboards, paint, drywall, a wide variety of personal-care products and dry cleaning.

But a whiff of good news on the home front: a study conducted by a University of Georgia team shows that at least five common houseplants cleanse the air of some nasty VOCs.

“I’m really excited,” said Dr. Stanley Kays, a professor in the department of horticulture and the lead author of the study. “I see a real potential positive health impact if we learn how to utilize plants to create a healthier environment,” he told Allergic Living.

The research team tested 28 common indoor plants for their ability to remove five toxic indoor pollutants: benzene (particularly found in drywall in Georgia), toluene, octane, trichloroethene (TCE) and alpha-pinene. “The VOCs tested in this study have a potential to seriously compromise the health of exposed individuals,” Kays said.

What floored him was the sheer volume of these compounds in the households. “When we started checking the air quality in some of the houses, it was shocking, unbelievable. We identified 179 VOCs in just two homes. It reiterated that we have a real problem here and most people have no idea about it.”

The Top 5

Of 28 plant species tested, five emerged as the best VOC eliminators.

• Purple Waffle Plant (Hemigraphis alternata) This attractive plant has puckered, slightly curled leaves that show off a red underside. It’s professor Stanley Kays personal favourite, a VOC-eliminating powerhouse.
• English Ivy (Hedera helix) The lush, fast-growing foliage makes for a nice hanging or climbing plant as ivy sucks up the UGA’s quintuplet of VOCs. Do keep out of reach of toddlers and pets, as the leaves are toxic if eaten.
• Variegated Wax Plant (Hoya carnosa) This tropical develops beautiful blooms in the summer, and its exquisite two-tone foliage inhales your household pollutants all year long.
• Asparagus Fern (Asparagus densiflorus) The plant’s abundant greenery scrubs toxins right out of the air. Meantime, the elegant spikes will perk up a room in the dead of winter. Don’t eat the berries, which can irritate the intestines; the plant can be toxic to pets.
• Purple Heart Plant (Tradescantia pallida) A favourite from the spiderwort family, this plant with its elongated, purple leaves out fills out to a full, beautiful hanging pot. Researchers rated it as superior for its ability to remove four of five VOCs – benzene, toluene, TCE and alpha-pinene.

On the Horizon

While this study is preliminary research, Kays is optimistic about being able to offer plant “prescriptions” in future. “I think we can really increase the health of people by the precise use of plants in interior spaces,” he says. A few pretty plants for much better breathing? Sounds like an idea that will blossom.

From the Winter 2010 issue of Allergic Living magazine.
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