The circle of life

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Gardens are fun places. It’s where children and pets play, where seedlings and shrubs are nurtured and where gardeners spend many happy hours tending beds and borders. With the spotlight so firmly focused on green issues, it’s clear that gardeners have a role to play in the broader community – after all, a healthy garden is the foundation of a healthy neighbourhood.

It’s easy to assume your backyard garden is healthy while plants flower, shrubs require pruning and the lawn needs frequent mowing. But it’s not that simple. For a garden to be truly healthy – or sustainable – there needs to be a relationship between four natural processes – the water and nutrient cycles, energy flows and biodiversity. Conservation and support for these processes characterize healthy gardens.

Ways with water

Gardeners can’t control where rain falls, but they can take natural drainage patterns into account when planning a garden. Deal with water where it falls. Consider installing water management features such as bioswales and rain gardens. Bioswales are depressions created in the earth to provide a place for rainwater to soak into the soil. Rain gardens also feature shallow depressions however, these are planted with water loving trees, shrubs and flowers. Site a rain garden where it will capture runoff from your yard and allow the water to soak into the ground. This reduces stormwater runoff – that could be carrying pollutants – from flowing into local streams or drains.
Reducing paved areas and using permeable paving will also reduce the speed and volume of runoff water and encourage infiltration.

Cut down on evaporation by planting canopies of vegetation and applying seasonal additions of 5 cm of composted mulch. During wet weather, mulch also lessens the impact of rain and encourages water infiltration.

Select plants to suit the moisture conditions of the site and early morning watering using drip or trickle irrigation systems will conserve water and reduce evaporation.

A practical way to cut down on using municipal water is to collect rainwater to use during dry weather. Many municipalities offer residents a special price on 75-gallon plastic rain barrels. Unchlorinated and oxygen-rich, rainwater is a natural option for the gardener who is mindful of the environmental impact of using potable water for irrigation.

The nutrient cycle

Of all horticultural practices, those that contribute to healthy soil are probably the most important. Healthy populations of soil fungi, bacteria and earthworms facilitate the continuous cycling of nutrient resources from air, water and soil to living organisms and back into non-living systems. Just as the water cycle depends on absorption, retention and drainage, nutrient cycling requires soil building to ensure healthy soil. Take care not to overwork the soil as this can make the soil vulnerable to erosion and break the nutrient cycle.

Excessive fertility disrupts the cycle and also benefits weeds. Incorporating 15-30 cm of compost during garden installation followed by 5 cm applications in spring and fall promotes moisture retention and drainage and soil pH that is favourable for the organisms in the soil and encourages nutrient availability.

Preserve and protect existing soils by restoring damaged areas with compost, biosolids or manufactured soils made of recycled local components. Aim to produce a soil with a chemistry and fertility similar to those in healthy regional sites. These are the soils that cycle nutrients and support habitat, resist erosion and also break down pollutants.

Soil structure is easily damaged by compaction and by working soil when it’s wet or frozen. Preventing compaction by adding compost and avoiding use of pesticides and fertilizers that damage soil life will conserve and support the nutrient cycle.

Energy flows

Inputs of energy, water, and materials can be maximized in a garden system through composting and recycling paving and building materials. Using local and regional materials and resources makes sense: The energy involved in the extraction of raw materials, processing and manufacturing plus waste are all part of the flow of energy. Alternatives to gas powered equipment such as reel mowers reduce fossil fuel emissions and decrease outputs of green waste by recycling grass clippings onto lawns to serve as fertilizer.

Selecting the right plant for the right place decreases the need for irrigation, maintenance labour for pruning, and resource use for fertilization. Native plants are generally less susceptible to pests and disease if grown in an undisturbed location.

Energy conservation is also supported by garden design that influences the efficient heating and cooling of buildings and in turn, communities. Orienting plant material to provide summer shade and winter sun, channeling or screening winds and increasing and decreasing humidity by adjusting air movement will enhance garden microclimates.


Not unlike natural landscapes, established gardens form an ecosystem of diverse living organisms, including humans that depend on their interaction with one another and their environment. From an ecological perspective it is apparent that gardens are not isolated – what we do has a ripple effect.

Selecting a variety of plants adapted to site conditions to create whole habitats that provide food and refuge over a long season will encourage beneficial insects, mammals and birds. A sustainable approach that supports biodiversity ideally links naturalized gardens, streetscapes and community greenways.