If you’ve been suffering with itchy, sneezy, runny-nosed pollen allergies, you aren’t alone. In the spring, when tree pollen counts reach peak levels, even people who rarely experience problems reach for their hankies and antihistamines.
You can’t escape airborne pollen altogether, but Thomas Ogren, author of “Allergy-Free Gardening” and “The Allergy-Fighting Garden” (Ten Speed Press) argues that you may breathe easier by choosing the plants you live with more carefully. Skeptics point out that pollen from trees and grass can travel long distances and cast shade on his theories — but Ogren stands behind his decades of research.
At the heart of his books are allergy ratings for a compendium of individual plants. Armed with the knowledge of which species or cultivars are extravagant pollen producers and which yield little or no pollen, the allergy-prone gardener can at least avoid the worst.
A pollen grain is a male reproductive unit in seed-producing plants — think of it as a plant’s version of sperm. Its mission is to reach female parts of the same species. In some self-fertile plants, those female structures can grow on the same plant, or even within the same flower. In other cases, where the plant has male and female forms, pollen must be transferred to another plant entirely to produce viable seeds.
Insects, birds and even certain mammals such as bats accomplish this for some plants that tend to have heavier, stickier pollen. But other plants rely exclusively on wind transport, and these are the most prolific producers of irritating pollen.
Ironically, it is primarily plants with inconspicuous or modest-looking flowers that are the worst offenders. Trees launch the allergy season, but it’s not so much the showy dogwoods, cherries and plums that make you itch — it’s the ashes, beeches, oaks, maples, poplars and sycamores that are choking you. In mid-season and early fall, grasses and weeds are the worst culprits, with the infamous ragweed producing up to a million grains of pollen each day.
The chemical makeup of pollen also factors into whether it is likely to rate as a respiratory irritant. Specific gravity, or the weight of individual pollen grains, also counts. While pine, for instance, produces lots of pollen, it’s fairly heavy and tends to fall straight down around the base of the tree, rather than scattering.
The length of time a plant releases pollen during the season and the shape of pollen grains are other considerations. Some pollen grains are shaped like miniature cactus balls, with sharp “spines,” and these may cause problems by mechanical action alone.
An allergy is an immunological reaction to a normally harmless substance. Allergies can surface at any time through mid-life, although often they appear in childhood.
The difference between a cold and allergies, which often present the same array of sneezing, stuffiness, drippy noses and coughing is a matter of duration — colds generally don’t persist for more than a week or so, while allergies can go on and on. Itchiness, not a component of colds, is another giveaway.
When you start thinking about the pollen producers near you, consider first the trees, which are the biggest offenders. Ogren blames the use of male cultivars of landscape trees, popular because they don’t produce litter in the form of fruit or seedpods. They do, however, produce clouds of pollen.
Female trees don’t just refrain from producing pollen — they sweep it from the air. Pollen has a negative electrical charge, while the female part of the flower, known as the stigma, has a positive charge. It attracts grains of pollen and neutralizes them when they adhere to its sticky surface.
Some notoriously allergenic trees like maple include excellent, female cultivars including ‘Indian Summer,’ ‘Morgan,’ ‘Rubescens’ and ‘Autumn Fantasy.’ Breeders have also produced sterile hybrids of some favorite trees — the ‘Stellar’ series of dogwoods, for instance.
Among the evergreens, junipers are especially high on the allergy hit-list, except for berry-producing females, like the shrubby Juniperus virginiana ‘Pendula Chamberlaynii’ and ‘Pendula Virdis, or the ground-covering Juniperus horizontalis ‘Bar Harbor,’ ‘Emerson’ and ‘Glenmore.’ Popular ornamental grasses may cause problems since most produce wind-borne pollen.
You don’t have to avoid showy garden flowers, though, since many of these are bee-pollinated. Good choices include annuals like petunias, morning glory and salvia; perennials including delphinium, foxglove and peony; and summer bulbs such as begonia, canna and crocosmia. Cacti are fine, and so are orchids.
The low-allergy garden can even include roses, believe it or not. Look for roses with lots of petals, like the overblown old-fashioned kinds, rather than single flowers, which expose pollen-laden stamens.
You needn’t rip out every plant that might cause problems — maybe moving it away from outdoor living spaces or bedroom windows is all it will take to cut down on exposure. Checking how plants rate on the potential allergy problem list is one helpful tool that could bring sufferers a bit of relief. Every little bit helps.