When I was a kid, my friends and I spent long summer days outdoors, picking daisies, observing roly-poly (also known as pill) bugs, holding caterpillars and trying to catch fireflies (lightning bugs).

Gardening might not be the first thing that comes to mind when thinking of children’s hobbies, but Frances Tophill is on a mission to change that. The horticulturist, author and TV presenter believes ...