Materials for hard landscaping, especially when newly manufactured and transported from the other side of the world, can have have a huge carbon footprint. Some of the most commonly-used materials are also the most carbon hungry.
Cement – used to make concrete – contributes almost 1kg of carbon dioxide for every 1kg produced, although some is reabsorbed as concrete is exposed to the air. Bricks add 250g per 1kg, and every square metre of stone patio adds about 47.5kg of carbon dioxide, depending on the stone.
A sustainably designed garden can still have patios and paths, but they’re kept to a minimum and made from recycled ceramic “gravel” or reclaimed stone slabs. The sustainable garden has pergolas with untreated, locally sourced red cedar, and second-hand garden tables and benches, or handmade items in green oak. Don’t buy materials unless you have to, working with what you already have in the garden.
Sourcing locally helps lower the high carbon cost of transporting heavy items. Second-hand or reclaimed materials from salvage yards carry a fraction of the carbon cost of new ones. They’re also unique and lend your garden a timeless, classic look that’s difficult to achieve with new materials.
Treated softwood may be cheaper, but it’s usually preserved with toxic chemicals or heat-treated (with all the carbon emissions that implies).
Instead, use naturally durable timber such as western red cedar or green oak. These have a traditional look and will last for years. Or paint the wood yourself, with a mineral based eco-friendly wood preservative.
How you use hard landscaping really matters. Large expanses of paving reflect heat, especially at night, adding to poor air quality and the “heat island” effect in cities.
Paving also contributes to flash flooding by stopping water filtering back into the ground. Keep it to a minimum, use permeable materials like gravel, and maximize rainwater-absorbing planting to create a softer garden, which is gentler on the environment, too.
More low-carbon gardening ideas