How to: create a low-allergen garden
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For many Australians spring launches a misery of sore eyes and runny nose.
Linda Ross lines up the perpetrators of this annual horror and reveals the safest, low-allergy choices for the garden.
The main culprits of plant allergy are trees with airborne pollen. Trees that originate in the northern hemisphere, such as conifers, oak, liquidambar, maple, ash, birch and poplar are the worst offenders. The flowers are insignificant, yet they send clouds of pollen into the air, and into our eyes and airways. Plane and sycamore (Platanus spp.) trees produce a fuzz on their leaves and stems which becomes airborne and can make life hell for people who live where these are street trees. Some trees, including conifers and poplars, are separate-sexed (dioecious). The male trees produce the pollen and the female trees produce the cone. You might assume, therefore, that all trees in public parks, schools and street plantings would be female. No such luck.
The aptly named asthma weed or pellitory (Parietaria judaica) is the usual suspect here. Its sticky leaves are found growing in the cracks of footpaths, walls and rocks and it produces huge amounts of pollen in spring. Seeds blow in from other areas and make control in the garden difficult. Spray with a glyphosate herbicide, such as Roundup or Zero, as the weed can reshoot from root pieces if pulled by hand.
Cool-climate grasses such as rye fill the air with massive amounts of pollen, especially when mown. Survival strategies include wearing a mask when mowing, or paying someone else to do the mowing. If these don’t work consider replacing the lawn with buffalo, which produces less pollen than other lawn grasses, or with an Australian grass such as Weeping Grass (Microlaena stipoides) or Kangaroo Grass (Themeda triandra).
Look for flowering plants with nectar and heavy pollen grains. These plants don’t release their pollen into the air; instead they transfer it to other flowers with help from birds and insects. As a rule most brightly coloured large flowers are safe, such as hibiscus, frangipani, Chinese lantern, lavender, citrus, camellia, tibouchina, petunia and pansy. Nectar-rich natives, such as grevillea, banksia, tea tree, bottlebrush, Queensland firewheel tree (Stenocarpus sinuatus) and ivory curl tree (Buckinghamia celsissima), are a good choice. The exception to the ‘plant Australian’ rule is Grevillea ‘Robyn Gordon’, which is a common cause of contact dermatitis.