August Garden Notes: Environmental Claims about Plants

The Horticultural Trades Association, the nursery and garden centre trade body, has produced an evidence base to support environmental claims about plants. Many claims are made about the benefits of growing plants and trees, so it is good to know that these claims are backed up by research. As we enjoy the rich diversity of our gardens this summer, it is good to feel positive about their effects on the environment. Claim 1 - Plants in garden spaces are vital for providing pollen and nectar for pollinators: Studies have shown that more bee and hoverfly visits are recorded in allotments and domestic gardens than in other land uses. Claim 2 – Plants help regulate temperature in cities, i.e., providing urban cooling and trees providing shade: In the city of London, the estimated annual cooling effect of gardens is -0.24°C. If cities increased tree coverage by up to 30%, this could lower temperatures by an average of 0.4°C and up to 5.9°C in some areas. Claim 3 – Plants can help clean and purify the air: Urban vegetation removed over 26,000 tonnes of ground-level ozone in 2021. Despite woodlands accounting for 12% of the UK land area, they remove over 80% of all 2.5-micron and smaller particulate matter from the atmosphere. Claim 4 – Trees are carbon sinks that store carbon in their trunks and leaves: Trees across the UK sequester around 16 million tonnes of CO2 equivalent per year. There are also studies showing how plants and trees help with water management by slowing runoff, acting as physical barriers to pollution, and naturally improving animal biodiversity. I find it reassuring to know we are all helping the environment as we enjoy our green spaces, whether they are well-tended or overgrown and “re-wilded.” David Hogg Buckland Nurseries