Kate surprised customers at Fakenham Garden Centre, near her Anmer Hall home in Norfolk on Thursday, as she dropped in to show her support for local businesses.
As she shopped for seeds and plants for her family, she told owners Martin and Jennie Turner: "They love it. It's such a great space for children and families to come to garden centres."
The Duchess said George loves playing with Venus fly trap plants and that he and his siblings have been growing tomato plants at home. "They were very excited to grow them from seeds and now they're as tall as them," she added.
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Keen gardener Kate wanted to encourage people to visit local businesses as they start to reopen. She said: "I've been food shopping, but I have to say I haven't been out a huge amount more but it's good and so important, now as things start to ease, people know they can go out and particularly to places like this."
She also said that she and husband William had found the social effects of the pandemic unsettling, adding: "When we do our food shopping we notice that everyone keeps their head down and it's hard for that social interaction."
The Duchess has long promoted the benefits of spending time outdoors and said: "It's come up in so many different conversations whether it's food, volunteering, and in all the mental health work that we've been doing, about how everyone is benefitting from being outside. So yes, they've been in lockdown but loads of families have been out on walks, more than they would do, outside."
She also wanted to hear how the family-run, independent garden centre had been affected by the Covid-19 outbreak. Martin told her they had had to furlough 15 out of 50 staff members, with four of five being made redundant. The business was closed for seven weeks until May 15.
"This has been the most challenging thing we've ever experienced," he added. But he said people had been keen to buy plants once the shop reopened three weeks ago. "There's been a massive upsurge hasn't there as people have been spending so much time outdoors and in their gardens," said the Duchess.
Told lots of first-time gardeners had been shopping, she smiled. "Really? That's great. And now people have the time to do it."
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Kate said she had had difficulties getting tomato seeds for her children to grow because everyone now wanted to grow tomato plants.
On her first public outing since March 20, she looked relaxed in brown jeans, a Fjallraven padded hunting waistcoat, Superga khaki trainers and her green onyx Siren earrings by Monica Vinader.
She asked staff including Michaela Giura, 35, from Norwich, and Tobias Davies, 47, if they were glad to be back at work and smiled in agreement when they asked if she was too. "It's good to get a structure and a routine back isn't it?" she said.
Sam Wade, 53, from Fakenham, who has retrained to use the tills since the coffee shop closed, said: "It's amazing that Kate came and showed everyone we're open for business. That's exactly what the royals should be doing."
The Duchess also spoke to customers including Wendy McNeil, 72, from Holme Hale. "Have you been doing lots of planting?" she asked. Wendy later admitted that she hadn't recognised the royal as she shopped for herbs for her son's pub, The York, in Norwich.
"I was looking at herbs and there was another older couple and I just said to her 'oh everyone's doing herbs today' and I didn't realise it was Kate," she said.
She added: "It was lovely talking to Kate and she knew her stuff on gardening!"
The Duchess also spoke to Patsy and Mike Thompson, both 85, asking them: "Have you been able to see your family a little bit?" Patsy replied; "Yes, it's been lovely."
"Isn't she lovely?" Patsy said afterwards. "I thought 'Isn't that Kate?' and then we saw the photographers and Mike thought 'well it's not for our benefit!'
"It's very important for members of the royal family to be out and about to show Britain is open. We think they're marvellous particularly the Queen as we are great royalists. It's been a lovely day. Our plants by royal appointment!"
The Duchess has been living at her country home with her children and husband Prince William since March. This was her first in-person, public engagement since.
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