Mr Howarth closed the event by signing the Food & Farming pledge, promising to "champion the Year of Food and Farming" and to "pledge [his] support to educating young people about how plants grow and provide us with food."
"I am delighted to support the Food & Farming project. It's marvellous to get children engaged in such initiatives so they can learn where food comes from and how plants grow.
"I very much enjoyed the tour of the Botanic Gardens and I encourage as many children as possible to get involved in the Food & Farming year."