Gardening

What to do - and what not to do - to get your garden working against climate change

Dump your paving and boundary walls, embrace weeds and plant a tree

Replacing garden paving materials with more permeable options, such as gravel, can be a better option to improve drainage.

Fionnuala Fallon's face
Fionnuala Fallon
Sat Jan 27 2024 - 05:00

In a world being reshaped by climate change, gardeners are increasingly asking themselves what can be done to counter the destructive effects of extreme weather events. The answer, as we’re discovering, is to take a nature-friendly approach that supports and nurtures resilience.

One obvious example is the use of paving in our front gardens, which often double up as much-needed car parking spaces. Unfortunately the widespread use of impermeable materials such as concrete and Tarmac contributes significantly to the problem of urban flash flooding, resulting in water run-off that puts huge stress on struggling urban drainage and sewage systems already under pressure. Not only can this also contaminate wildlife-rich waterways as a result, but it contributes to soil pollution, leading to less than ideal growing conditions for the plants in our gardens and cities.

Impermeable garden paving materials also contribute to the problem of soil shrinkage during prolonged dry periods, sometimes leading to problems with building subsidence. In urban areas in particular they compound the problem of summer heat extremes, interfering with the naturally cooling effects of the ground. If you’ve ever walked down a city street in a heatwave you’ll have experienced this first-hand.

In this case the best solution is to replace garden paving materials such as concrete, Tarmac and tiles with any of a variety of permeable materials that allow water to naturally percolate through the soil. Examples include pebble or gravel laid on to an “open-graded” permeable hardcore base; pebble or gravel laid on to a moulded plastic or concrete “honeycomb” structure of interlocking cells that stabilises the ground and makes it suitable for heavy traffic (these structures are also known as “matrix pavers” or “geo-matrices”); open-joint brick pavers laid on a permeable base where the fine joints between bricks are left open for drainage’; natural stone laid on a permeable base where the joints are filled with a permeable mortar or left open; and hard-wearing lawns using species of grass recommended for intensive use, grown through a rigid plastic or concrete honeycomb structure similar to that described above, resulting in a resilient, permeable surface that can tolerate a surprising degree of heavy traffic.

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Unfortunately not all landscapers and designers follow best practice in this regard despite the efforts of city councils to highlight the problem. To find one that does check out the websites of reputable associations such as the Garden and Landscape Designers Association (glda.ie) and the Association of Landscape Contractors of Ireland (alci.ie).

Permeable paving aside, the simple act of planting even just one small garden tree helps to counter the effects of climate change in innumerable ways. Not only will its leafy canopy provide shelter from harsh winds, fierce winter frosts, torrential downpours and summer droughts (all of which negatively impact soil and plant health), but its large and intricate root system also naturally improves drainage and protects soil structure.

Trees also lock in carbon, clean polluted air, filter noise, and provide a precious habitat for countless species of garden wildlife, while the fallen leaves of deciduous species provide a nourishing and protective organic blanket for the soil at that time of the year when it’s most needed. Examples of species suitable for small gardens include Cornus kousa var. chinensis (Chinese dogwood), the Japanese maple known as Acer palmatum ‘Sango Kaku’, and the compact variety of serviceberry known as Amelanchier ‘Ballerina’, as well as cultivated forms of hawthorn (Crataegus), crab apple (Malus) and birch (Betula).

Unfortunately climate change also threatens the health of an increasing number of tree species as a result of the rise in pests and diseases (many of them new to our shores) as well as unfavourable growing conditions caused by flooding and drought. For a comprehensive guide to choosing climate-resilient species most suitable for your garden get your hands on a copy of “The Essential Tree Selection Guide for Climate Resilience, Carbon Storage, Species Diversity and other Ecosystem Benefits” by Henrik Sjöman and Arit Anderson, recently published in association with the Royal Botanic Gardens, Kew

No space for a tree? Then the good news is that garden hedges, especially flowering and fruiting kinds that use a high percentage of ultra-hardy native species such as hawthorn (Crataegus monogyna), blackthorn (Prunus spinosa), guelder rose (Viburnum opulus) and spindle (Euonymus europaeus), provide a similar range of benefits. But the same can’t be said for most garden boundary walls (dry-stone walls being the notable exception), which further contribute to the problem of urban flooding as well as the fragmentation of garden wildlife habitats.

Leaving aside the bitter cold and fierce storms experienced recently, Irish gardeners are also grappling with the growing threat of spring and summer droughts as a result of climate change, with similarly serious consequences for human, plant and soil health. Again a leafy, habitat-rich, wildlife-friendly, organically-managed garden, no matter how tiny, can do much to mitigate their negative impacts. As mentioned above plants’ leaves act as an all-important skin that protects and regulates soil temperatures, prevents excessive water loss through evaporation, and provides precious shelter for all kinds of garden wildlife from earthworms, woodlice, springtails and spiders to birds, insects and mammals.

The use of organic mulches using nature-friendly, peat-free materials such as home-made garden compost, well-rotted manure and leaf mould will also greatly help to nourish a resilient, healthy soil food web in your garden or allotment by adding organic matter, improving drainage and boosting beneficial soil microbial activity. If you don’t have enough of your own, recommended commercial Irish suppliers include geeup.ie; enrich.ie and envirogardenandhome.com. The same goes for what’s known as living or green manures used as cover crops that are then strimmed/cut back and either left as a mulch or incorporated back into the soil. Suppliers of seed of the latter include mrmiddleton.com; fruithillfarm.com and quickcrop.ie

Sadly biodiversity loss is yet another consequence of climate change, threatening the natural habitats and lifecycles of many native Irish species of plants and insects. Butterflies and moths, for example, are vulnerable to changes in temperature and rainfall amounts, which also impact upon the lifecycles of the native plants that they and their larvae depend upon for food.

These delicate symbiotic relationships rely on a complex but finely tuned seasonal pattern of breeding/egg-laying/plant growth/flowering evolved over thousands of years. A spring drought or late harsh frost, for example, can potentially have a devastating effect upon butterfly populations emerging from winter hibernation. In this case making some space in our gardens and allotments for common “weeds” and wildflowers such as nettles, trefoil, clover, violets and wild grasses that they favour as host plants for egg-laying can be the crucial difference to some species’ survival. So can avoiding the use of traditional garden chemicals including herbicides, fungicides and pesticides, and not being too tidy-minded. And if we can find room for even the tiniest garden pond to further enrich their habitats then all the better.

This week in the garden

Last weekend’s Storm Isha battered many parts of the country, leaving gardens sodden and bedraggled and causing damage to some trees and shrubs, so choose a dry, still, day if possible to check your garden or allotment for torn or hanging branches. Large, heavy hanging branches pose a serious health and safety risk, and should be removed by a professional tree surgeon or landscaper.

Sow seed of sweet pea in the coming weeks for young plants that can be planted outside in late March-April to flower this coming summer. For best results chit the seed by placing it on some scrunched up kitchen paper in a small sealed container placed in a cool room. Once the seeds sprout gently bury each individual seed roughly 2mm deep in small pots or root trainers filled with a good quality peat-free multipurpose or seed compost. Water well and place in a cool, bright but frost-free spot to grow on.

Dates for your diary

Saturday, February 3rd; Snowdrop Open Day at Coosheen Gardens, Glounthane, Co Cork T45CC42, see @hesterforde for further details

Thursday, February 8th, to Sunday, February 11th, (11am-4pm); snowdrop weekend at RHSI Bellefield Gardens, Shinrone, Co Offaly, R42NW82, including garden tours by its head gardener Paul Smyth at noon and 2pm, see rhsi.ie

Sunday, February 11th; Killruddery house and gardens, Bray, Co Wicklow, “How to Design, Plant and Nurture Your Own Cut-Flower Garden”, a one-day hands-on workshop with flower-farmer-florist and garden writer Fionnuala Fallon, see killruddery.com for booking details.

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