But before the monarch arrived, Kate was spotted picking up stray leaves and twigs and stuffing them into her designer handbag to ensure that everything was spotless.
During the tour of the ‘Back to Nature’ space, the Queen, 93, then remarked how tidy it was - it seems Kate’s last minute nerves paid off.
Her Majesty also reportedly made a joke about grandson William, saying “You're all looking very tidy.”
The duke, dressed in a navy suit, laughed and responded: “Well, I've smartened up.”
The Queen was remarkably close to the truth when she told Kate her garden looked tidy earlier. Before she arrived, the duchess was seen picking up stray leaves and twigs – and stuffing them into her designer handbag as she had nowhere to else to put them! #ChelseaFlowerShow pic.twitter.com/gYLXFllERm— Rebecca English (@RE_DailyMail) May 20, 2019
As Kate took the Queen on a tour, she pointed out many of the garden’s features to her, including a treehouse and rope swing.
The couple also showed her some of the activities that those experiencing the garden can enjoy, including Reed Boat making.
Earlier on Monday, the duchess made an unannounced visit to the site to show some local schoolchildren around.
Wearing a M.i.h Jeans broderie shirt, camel Massimo Dutti culottes and her Superga trainers, Kate climbed into the treehouse.
For the preview reception, she changed into a floral Erdem gown and Castaner espadrille wedges.
On Sunday afternoon, the Duke and Duchess of Cambridge took their three children to the Chelsea Flower Show garden to explore the place.
Photos and footage of Prince George, Princess Charlotte and Prince Louis playing in the garden were released after the visit.
George, five, was asked by his father to rate his mother’s garden out of ten.
He replied: “Twenty!”
William laughed and said: “Twenty out of ten? That’s pretty good. I think mummy’s done well.”