Kensington Palace has released new photos and video of the Cambridge children – including the first yet of youngest son Prince Louis walking as he explores the Chelsea Flower Show garden their mother, Kate Middleton, helped to design.

The toddler prince, who turned one just last month, has been snapped and filmed in the garden with his older sister and brother, Princess Charlotte and Prince George, and his parents.

“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,” the Duchess of Cambridge said.

Prince George and Prince William with Kate and Prince Louis. Photo: Kensington Palace

In video released later by the palace, the cute-as-buttons Cambridge kiddies can be seen climbing on rocks and playing on the swings in the Duchess’s garden, while their mother does some planting.

“This is a natural, creative place for them to play,” Kate says on the footage.

“I hope that this woodland that we have created here really inspires families, kids and communities to get outside, enjoy nature and the outdoors and spend quality time together.”

"I hope that this woodland that we have created here really inspires families, kids and communities to get outside, enjoy nature and the outdoors and spend quality time together." — The Duchess of Cambridge on the #RHSChelsea Back to Nature Garden pic.twitter.com/286B9TOPGA

— The Prince and Princess of Wales (@KensingtonRoyal) May 20, 2019

Kensington Palace shared a picture of the Duchess’ garden on Sunday, described it as a space “filled with incredible edibles, plants for craft activities, forest scents and a diverse range of plants”.

Organisers the Royal Horticultural Society tweeted a photograph of the garden, with Kate sitting on a rope swing.

“We invite you to take a sneak peek at The Duchess of Cambridge’s (hash)RHSChelsea ‘Back to Nature’ Garden,” they wrote.

“The garden includes a swing seat, hanging below the garden’s centrepiece, a high platform tree house.”

The Back to Nature garden was co-designed by Kate and inspired by childhood memories and families.

Prince George and Princess Charlotte in the garden. Photo: Kensington Palace

Princess Charlotte on a swing. Photo: Kensington Palace

RHS said the “woodland garden is a place to retreat from the world, to play, learn and discover as well as create special family memories”.

There is also a waterfall and stream which offer places to paddle, relax and build dams, while a hollow log presents a challenge of learning to balance as well as to climb, RHS said.

Another colourful display features thousands of chrysanthemum flowers in the shape of a rainbow.

There will be about 7000 chrysanthemum blooms on the National Chrysanthemum Society exhibit.

Prince Louis and Prince William. Photo: Kensington Palace

The Chelsea Flower Show will run from May 21-25 and is held in the grounds of the Royal Hospital Chelsea in west London.

It has been held in Chelsea since 1912 and is the most famous flower and landscape garden show in the United Kingdom.

The show is attended by members of the British royal family and attracts visitors from all continents.

-with AAP