Prince William and Kate Middleton took their three children to test out Middleton’s new project on Sunday afternoon.

Kensington Palace posted adorable photos of the royal family on social media Sunday night as they explored Middleton’s “Back to Nature” Garden at the Chelsea Flower Show in London. The Chelsea Flower Show is officially set to begin on Tuesday.

PRINCE WILLIAM AND KATE MIDDLETON VISIT BABY ARCHIE, PRINCE HARRY AND MEGHAN MARKLE

The series of photographs, by Matt Porteous, include a picture of Prince Louis, 1, running along a path and his older siblings, Prince George, 5, and Princess Charlotte, 4, sitting on a bridge with their feet in a stream.

“In recent years I have focused much of my work on the early years, and how instrumental they are for outcomes later in life. I believe that spending time outdoors when we are young can play a role in laying the foundations for children to become happy, healthy adults,” Middleton, 37, reportedly said ahead of the garden’s opening.

According to Kensington Palace, the whole family participated in preparing the garden for its opening.

“Over the past months, Prince George, Princess Charlotte and Prince Louis have helped The Duchess gather moss, leaves and twigs to help decorate @The_RHS Back to Nature Garden. Hazel sticks collected by the family were also used to make the garden’s den,” an Instagram post from the palace said in part.

The “Back to Nature” Garden was designed by Middleton as well as Andrée Davies and Adam White of Davies White Landscape Architects, award winning landscape architects. The garden is meant to bring people together to “connect with nature,” the palace captioned their posts.

The garden features a swing, a treehouse made to look like a bird or animal nest, and a “multi-sensory, green and blue plant scheme,” a photo caption said.

“The garden will be filled with incredible edibles, plants for craft activities, forest scents and a diverse range of plants, shrubs and trees of different heights and textures,” the caption continued.

The “Back to Nature” Garden is part of Middleton’s work with early child development.

PRINCE HARRY, MEGHAN MARKLE RELEASE UNSEEN ROYAL WEDDING PHOTOS FOR ANNIVERSARY

“The Duchess has committed to making early childhood development the focus of her work in the years to come, and believes that providing children with the opportunity to spend time outdoors can play an important role,” the palace described.

On Monday, Middleton visited again along with school children.

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Last week, Prince William and Middleton visited their new nephew for the first time.

Meghan Markle and Prince Harry hosted the Duke and Duchess of Cambridge at their Frogmore Cottage home to introduce them to baby Archie Harrison Mountbatten-Windsor, who was born on May 6th.

Fox News’ Jessica Sager contributed to this report.