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ANNIVERSARY
Creating a low-allergen garden Above, left inset: © Dorling Kindersley: James Young; Above, right inset © Dorling Kindersley: Mark Winwood/RHS Wisley
The recently published RHS The Wellbeing Garden, by Professor Alistair Griffiths and Matthew Keightley is an eye-opening practical guide to making your garden good for you. Themes include how plants can form a barrier against air and noise pollution, which birdsong alleviates anxiety and how plants can help to save energy – this excerpt is about how you can create a low-allergen garden
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ith the right plants, your garden can be a haven – even for allergy-sufferers – all year round. Although it’s not possible to eliminate all pollen-producing plants from a garden – or even desirable, since they are beneficial to bees and other pollinating insects – some plants will actually remove pollen from the air by trapping the grains. Other plants produce much lower levels of pollen, and so, with careful design and planting, allergy-sufferers can enjoy their gardens throughout the year. POLLEN AND ALLERGIES As any hayfever sufferer knows, not all plants bring a sense of wellbeing. For the estimated 10 to 30 per cent of adults and 40 per cent of children globally who suffer from hay fever, being outside when the pollen count is high is not always an idyllic prospect. Pollen is produced by the male reproductive parts of a plant and transferred, either by wind, water, or via insects and animals, to the stigma, the female part of a plant, for pollination. Fertilization then takes place and the plant produces seeds. Sex matters Perfect-flowered plants, such as some foxgloves, lilies, and roses, have both male and female parts together in the same flower. Monoecious plants, such as birch and hazel, have separate male and female flowers on the 84 TheBATHMagazine
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ocTober 2020
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same plant, while dioecious plants, such as holly, juniper, and some grasses, have male plants with only male flowers and female plants that have only female flowers. Male dioecious plants produce pollen, and the female plants produce fruits or seeds but no pollen. Some plants produce much less pollen than others (see opposite), and sterile plants, which have no male or female flowers, produce no pollen at all. Sterile plants, low-pollen producers, and the females of dioecious plants are the best choices for a low-allergen garden. Blowing in the wind Some wind and water-pollinated plants produce large quantities of pollen in order to be successful in reproducing and surviving, whereas many animal- and insect-pollinated plants produce less pollen to reproduce and survive. However, even within animal- and insect-pollinated plant groups, some produce less pollen than others. US horticulturist Tom Ogren created the Ogren Plant Allergy Scale (OPALS), which measures allergenicity of plants. A rating of one is the lowest and 10 is the highest. Birch, for example, has an OPALS rating of nine, while a foxglove’s rating is just two. Use this scale to help you to select plants for your garden with low amounts of pollen. A HAVEN FOR ALLERGY-SUFFERERS Allergies don’t have to prevent you enjoying your garden. With a few clever strategies, you
can design a space that will minimize pollen levels and ease allergy symptoms. Pick your flowers Colourful, eye-catching flowers, such as peonies, violets, and pansies, produce very little airborne pollen and these, along with flowers that attract bees and other pollinating insects, such as penstemon and antirrhinum, are generally the best choices for hayfever sufferers. Most double flowers also produce little pollen, and while they do not provide much food for pollinators, some, such as climbing roses, offer refuges and nesting sites for other wildlife. Plants with hooded or tubular flowers, including foxgloves and agapanthus, have low OPALS ratings. Ornamental grasses, singleflowered daisies, and chrysanthemums, on the other hand, should be avoided. If you really love the look of ornamental grasses, try female grasses or strappy-leaved foliage plants such as Libertia or Phormium, which have insect-pollinated flowers and a lower OPALS rating. Intensely scented plants such as wisteria and jasmine may trigger sensitivities to smell, so steer clear of these too. Lose the lawn Lawns can be great for wildlife, but are not ideal for allergy sufferers, so consider other ground cover or opt for gravel or decking. Hard surfaces can help to keep pollen airborne, so choose greenery to trap pollen
