But the RHS Chelsea Flower Show's website states that "we can not allow under 5s" - an age Louis and Charlotte fall below.
Kate has previously said she has "fond memories" of being outdoors as a child and is passing that passion on to her children.
It was clear just how close the pair have become over the years.
The Queen, wearing a lime and purple silk dress and matching plain lime coat by Stewart Parvin and a diamond flower brooch, walked around the rest of the show with Sir Nicholas Bacon, president of the Royal Horticultural Society, and Sue Biggs, the RHS's director general.
On Kensington Palace's official Instagram page, the Duke and Duchess of Cambridge released six intimate snapshots that offered an adorable glimpse into their lives as a family five, with children Prince George, Princess Charlotte, and Prince Louis playing outside.
Royal fans were thrilled to see the family enjoying the attractive space, with Prince Louis walking and his siblings, Prince George and Princess Charlotte, having an fantastic time exploring.
Naturally, since Middleton designed the garden with child development and play in mind, it was logical that her kids would get to give the space a look.
This time, Prince George takes centre stage as his dad Prince William asks him to rate his mum's garden design out of ten.
Britain's Catherine, Duchess of Cambridge, plays with her son Prince Louis at the Adam White and Andree Davies co-designed garden ahead of the RHS Chelsea Flower Show in London on May 19, 2019. In another shot, Charlotte is seen smiling on a swing seat, mimicking an earlier picture of mom Kate, 37, doing the same. She said: 'The children played last night in a way I hadn't imagined.
There were carrots and beetroot that the Queen remembers planting as a child with her sister Margaret, and a waterfall in tribute to the one she loves at her Norfolk home Sandringham. If the pure joy Kate's own kids, Prince George, Princess Charlotte, and Prince Louis playing in the garden is any indication, the garden is definitely going to inspire lots of kids to play outside more. Charlotte looks adorable in a floral dress flawless for playing in a garden while George got to go casual as well in a blue polo shirt and shorts.
The "Back to Nature" Garden was designed in cooperation with award-winning landscape architects Andrée Davies and Adam White. 'Children - both hers and others - have always been at the heart of this project'.