Fiann Ó Nualláin looks at how you can allergen-proof your garden in plant and design choices
Breathe easy gardens
ACCORDING to the European Federation of Allergy and Airway Diseases Patients’ Association, over 80 million people in Europe currently have some form of allergic condition. From food intolerance, reactions to pet hairs, sensitivity to ingredients in soaps and shampoos, the predominant life strategy is avoidance of the triggers. When it comes to gardening there are several potentials for allergic reaction.
At some point in your life, diagnosed allergy sufferer or not, you will have encountered phytodermatitis (plant contact irritation). Some plants like nettles will cause a reaction to every individual they come into contact with, while others like Chrysanthemums may cause a rash to some gardeners but not to others.
There are three types of Phytodermatitis; irritant, allergic and photosensitive. Irritant dermatitis beyond the acute category of nettle sting also has a chronic side, triggered from repeated contact with prickly or thorny plants (including roses) where episodes of redness, itching and even blisters occur from a slow sensitising, much in the way most allergies develop.
Allergic dermatitis is triggered by handling a plant substance that you are allergic to — some plants contain irritant components in high enough concentrations to affect the general population and others in lower concentrations only affect a reaction in the sensitive portion of the population.
If you have a food intolerance for cashew nuts or mango you will have a sensitivity to any encounters with urushiol (the chemical component of poison ivy), present in low quantities in ginkgo and alstromerias too. Some bulbs trigger reactions via calcium oxalate, including daffodil and hyacinths. If anyway sensitive, avoid Primula, Euphorbia, Chrysanthemum, Rhus spp and Zantedescia.
Photocontact dermatitis is triggered by a reaction of sunlight to a residue of a phototoxic plant on your skin. Weeds like Giant Hogweed (Heracleum mantegazzianum) release a sap that blisters the skin while contact with garden staples like
Rue, Sorrel, Oleander, Sanguinaria, Boxwood and Yew can trigger photosensitive rashes and blistering.
The World Health Organization’s 2007 Global surveillance report on respiratory health concluded that worldwide an estimated 300 million people suffer from asthma. Nearly 500,000 of those live in Ireland. The major culprits of garden triggers for asthma are inhalant sources: Fungal and mould spores, plant spores, insect and animal dander and of course pollen grains.
Precautions for asthma are beneficial to hayfever and other sinus and respiratory complaints. Avoid ferns and other spore- bearing plants. Avoid bog gardens, stagnant water and pots in shady spots where mould accrues. Avoid working with wet mulch, raking damp leaves, and home-composting: aspergillus fumigatus, a natural constituent of soil and compost heaps has been found in the phlegm of many asthmatics.
Don’t rush to cover your soil with woodchip or other organic mulches that may promote spores and moulds, opt instead for gravel or groundcover plants. Avoid plants prone to mildew and other powdery diseases that could be inhaled. In fact, select virus, disease and pest-free plants exclusively if you can. Limiting chemical usage will benefit your health and the natural environment of your garden.
Introducing plants that attract birds, for example, a female tree with edible berries, will limit insects and their dander from your garden and also at nesting time, remove good quantities of animal hairs and other detritus. Keep on top of insects via organic methods and keeping plants healthy. Sick and neglected plants attract insects and insect secretions or “honeydew,” is a primary host for many moulds.
Note: Moulds and fungi are active in all seasons other than frosty winters while the pollen season starts in February with the tree pollens then lulls a little in mid spring but rises again with the prevalence of grass pollen from late May to mid-August, and even if you cut your grass regularly to defer it flowering, grass has the capacity to flower at various heights.
Limiting lawn area is a good option and it can be outright replaced with paving or squeezed by widening your borders filled with low and no-pollen plants. Most weeds and many wild flowers release their pollens from June to late September.
Avoid trees with catkins as they evolved to disperse massive amounts of pollen into the air and avoid wind pollinated garden plants, it is not just a case of opting for bee pollinated plants but plants which flower in the shape of bells and trumpets so pollen is enclosed. i.e Campanulas, peonies, lilies (if lightly fragrant as fragrance can be a trigger with some). Also, consider doubles and female plants. Female plants produce no pollen. Most hybrid plants are effectively feminised clones.
You do not have to miss out on your favourites. If you love Chrysanthemums (or other ornamental daisies) and it is not a dermatological trigger to you, then you can seek a double-flowering variety, or if you love roses, apart from varieties that bees have to climb into to get near pollen, most bear heavy pollen grains so any airborne dispersal will fall quickly from your breathable air. The great news is that you can have a garden of floral abundance and more diversity is good as it limits potential sensitising to a dominant species.
To help you get under way, here is a sample A-Z of some other low allergy plants: Antirrhinums; Aronia melanocarpa; Berberis vulgaris; Cranebill geraniums; Dianthus Daphne epimediums; Fuchsia; Helianthemum; Hemerocallis; Heuchera; Hostas; Hydrangea grandiflora; Iris; Kniphofia; Pachysandra; Papaver; Penstemon; Phlox; Physalis spp; Sempervivums; Viburnum; violas.
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