Feeling blue: the dye has ties to slavery

One mother, two boys, on a trip around the world to seven countries to find the origin of seven colours

We are in the world of ghosts, where Spanish moss drapes from the branches of bowing cypress trees and where the past still brushes up against the present.

Middleton Place is an 18th-century plantation home in South Carolina, and site to one of the oldest landscaped gardens in the United States. We walk through paths fringed with blazing azaleas, magnolias, and crepe myrtles, listening to the call of the white egret, as alligators sun themselves on the neatly cut grass banks beside the duckweed-covered Rice Mill Pond.

We are here in search of indigo, once the most important dye in the world and whose cultivation supported plantation slavery in the 18th century. It built an empire, and later destroyed it. To find it we must seek out the ghosts of the past, walk from the grand to the simple, from the rich to the poor. For indigo comes with a painful legacy that's still relevant today – not least in nearby Charleston, still mourning those lost in Emanuel, one of the Deep South's most historic churches.

Today though, there are only two people working in the old slave yard, both volunteers in their early sixties. They stand by a large metal vat, stirring a blue-black liquid that is the colour of the night sky. Indigo. "We still grow it here," John tells us, nodding towards a patch of ground that is full of small leafy plants.

"Yup," concurs Ralph. "Lot of memories in those stems."

"You got a white 'kerchief or something? I'd be happy to dye it for you, ma'am," says John.

The only thing we have that is white are my son's grubby socks. "They'll do," says Ralph and, a little reluctantly, Dow takes off his shoes and peels his socks from his hot feet.

"You'll need to bind it with some vinegar. And if you've no vinegar …"

"... Urine," finishes off John, walking towards us. "We're not meant to do this," he adds, "but you can take this." He pushes something into Dow's hand – a small ball of dried, crushed indigo. "Precious that," he says. "That colour comes with a history we don't like to think about too much."

Lindsay Hawdon's debut novel, 'Jakob's Colours', is published by Hodder & Stoughton (£14.99). The Rainbow Hunters are raising money for War Child (justgiving.com/Lindsay-Hawdon). They are supported by Inventing Futures (inventingfutures.org).