No matter how small or large your garden, it is likely to be bordered by fencing, wall or hedge.
The ideal green boundary is a hedge - a living fence. Hedges have become rare commodities in today's countryside, with large commercial farms having ripped out many to make way for larger fields and to allow farm vehicles access.
Hedges are hugely valuable as a home to birds, animals and insects, as well as providing a safe habitat for wildflowers and other plants. But on a practical gardening level, they also act as far more effective windbreaks than fences. Wind tends to bounce up and over when it hits a solid boundary such as a fence, and swirling on the leeward side often damages plants. This can also create the conditions that lead to fences being blown down. Hedges on the other hand filter and slow wind down and every 30 cm (1 ft) of hedge height offers 3 m (10 ft) of shelter.
So you will be helping both the conditions in your garden and the environment as a whole by keeping any existing hedges and planting others if you have a suitable space. It need not be at the edge of your property - hedges can also be used to segregate different areas in the garden, such as a lawn from a vegetable patch.
If you are not convinced of the merits of hedges over fences then choose your fencing carefully. If you prefer walls then make sure they are built using reclaimed bricks or stone if at all possible, or, failing that, select a stone that is local to your area. If you are painting or staining fences or walls then remember to choose natural organic products that do not use petrochemicals.
Finally, use the walls and fences as vertical canvases on which to continue your garden by fixing trellises on them and growing climbing plants such as vines, clematis, honeysuckle or wisteria. Western red cedar wood is commonly used to make trellises, but the Canadian forests from which the wood comes have not been well managed so avoid this wood unless it has the Forest Stewardship Council (FSC) mark.