A Princess Diana memorial garden has opened at Kensington Palace, her former home, as a celebration of her life 20 years after her death in 1997. And there's a touching story behind it.

The palace's "Sunken Garden," where Diana used to sit and chat to the gardeners, has been carpeted with white flowers in a stunning tribute.

The idea for the garden came from Kensington Palace's head gardener Sean Harkin after he spoke with staff who'd worked in the palace's gardens when the princess lived there."She would come by the Sunken Garden and she would admire the floral displays in here as they changed through spring and summer and she would chat with them," says Harkin.

"It seemed a very special memory, so it seemed we should do something this year to celebrate that memory," he said.

Gardens and estates manager Graham Dillamore, who's worked in the palace gardens for 30 years, remembers when the princess would stop by the gardens to admire the gardeners' work.

"I can often remember seeing her run past very early in the morning and if it was quiet she might pop in and say hello and compliment us on the colour schemes that we were doing," says Dillamore.

The garden -- which will be open until September -- has been planted up with a sea of white tulips -- including one variety named Diana -- in addition to scented hyacinths and daffodils. There's also a swathe of white Forget-me-Nots, which were a favourite of the princess.

In mid-May the gardeners plan to change the planting and introduce a selection of white roses around a pool in the garden. They'll also add white lilies to the beds.

The garden is intended to celebrate Diana's "elegance, vivacity and style" with its sea of white flowers, which includes some of the princess' personal favourites, according to a palace statement.

"As we’ve been working in the garden, many of our palace visitors have stopped to talk to us and share their own memories of Diana, Princess of Wales. We hope that our garden captures the energy and spirit that made her such a popular figure around the world," says Harkin.

The garden can be accessed for free by the public and will remain open until September 2017.