The new 320m-long Great Broad Walk Borders at Kew are probably the longest in the world
The ambitious project to develop borders along the Great Broad Walk at Royal Botanic Gardens Kew was developed by Richard Wilford, Kew’s Head of Design, with £1.5 million raised by donation to pay for its implementation and ongoing maintenance, and the project has been widely hailed as a success.
The history of the Broad Walk dates back to the 1840s, when William Nesfield devised it as a grand promenade from the Orangery to the Palm House. He specified a series of round beds and an avenue of cedars on either side of the path.
Wilford was inspired by Nesfield’s layout to base his own design on a series of circles, straddling the path to form semi-circular beds. “The circles had to work around the existing rows of cedars,” he explains. “Initially I considered creating distinct beds, like Nesfield had done. Then I realised linking the circles produced long borders with a stronger visual impact.”
Signage was important, given Kew’s mission to provide information as well as inspiration. “Labels in the ground soon get buried, so we put an information board by each semi-circle,” says Wilford.
Half the budget was spent on resurfacing the main path and installing drainage. The existing surface was flood prone, with degraded tarmac laid on a poor quality sub-base. “The base dated back to the 1840s, but we couldn’t afford to redo it. Instead, we used the Terrabase system, a 30mm-thick resin-bonded porous surface laid on to a felt-type mat which was put down over the original surface. Because it isn’t bonded directly onto the sub-base, it has an element of flexibility which is quite forgiving.”
The planting ground had been under turf, so there were no pernicious weeds to deal with. The soil was improved with manure, straw and composted plant material and an irrigation system was installed. “We’d had bad experiences with leaky pipes, which our squirrels loved, so we used overhead irrigation plus pop-ups along the path.”
Devising a planting plan which was technically appropriate for a botanical garden while delighting the casual visitor presented Wilford with another challenge. “This was planted for big swathes of colour from June to September, and we decided we could use cultivars to ensure the most impressive display.” Each circle has a different subject or theme.
One area is devoted to Lamiaceae, which is a plant family Kew does a lot of scientific work on, but includes many desirable ornamentals. Other zones take a thematic approach, such as seed dispersal. In total the beds contain almost 30,000 plants, which was more than the Kew team could propagate, so the contract was put out to tender, and Crocus was appointed as main supplier. The bulk of the planting was done in spring 2016, with bulbs added in autumn.