‘Brownfield’ garden a first for Chelsea
CHELSEA Flower Show visitors might usually expect to see green lawns and perfect landscaping. But this year the show is to host a “brownfield” show garden for the first time to help urban horticulturalists fix contaminated soil and help their plants thrive.
Designer Paul Hervey-Brookes said he is increasingly coming acro s s gardeners frustrated by poor soil, particularly in new developments built on former industrial sites. The problem can be a legacy of coal use in city centres, which leaves the ground acidic and difficult to grow on.
“Lots of people inherit these sites where the soils are actually heavily contaminated with heavy irons. The topsoil has been removed. It’s not in a great condition. They don’t have the necessary experience or knowledge to buy the right plants for that place, and everything fails,” he said. Such land is often compacted and lacking in nutrients and oxygen, making it difficult for plants to grow.
The first step to repairing poor-quality soil is to incorporate biochar, a type of very highly heated charcoal, which traps oxygen in the soil and expands it to allow plants to grow.
The show garden will incorporate plants that have “hairy” leaves to trap this airborne soil, as well as plants that have a taproot, which can push into tough soil and break it up, introducing oxygen. “What you’ve inherited is the subsoil, and you’re planting into it to try and make those plants anchor in new nutrients. It’s a slightly more long-term version of just buying in new topsoil, which is a bit resource wasteful,” he added.
Recommended plants include raspberry, which has roots good for opening up soil and foliage which spreads over a wide area, pendulous sedge, anthriscus, angelica and galega, a nitrogen-fixing plant which adds fertility to the soil.