Instead, the BBC presenter has ignited controversy by telling growers to stick to our native species and turf out foreign ones.
Don - who recently hosted the Around The World In 80 Gardens series - now stands accused of trying to uproot thousands of years of plant-collecting history in the UK.
At the Oxford Literary Festival, he told his audience: "British gardeners must learn to tell you a story through their gardens."
"Gardening with indigenous plants and working with nature by tweaking it is so much more interesting than imposing on to the natural world."
"The interesting gardens are related to geographical/historical/ personal context."
"Growing plants in a garden that would not exist without you is not very interesting."
In a recent interview, the Gardeners' World presenter - who has pledged to plant only native species in his Herefordshire garden - said: "Elsewhere in the world, indigenous plants play a key part in establishing national identity."
"We have an incredibly rich and fascinating plant heritage which we downplay - so I am planting oak, ash, hawthorn, yew, aspen and alder, as well as primroses, violets, roses."
"He is confusing biodiversity and native plants. Plants and trees are used for social, economic and environmental reasons."
Luke Harding, manager of Westonbirt-plant centre, said: "Doing away with 'foreign' plants would effectively wipe out several thousand years of plant- collecting history.
"The vast array of non-native plants available in Britain is something that we are recognised for and that has given us our identity."
Nottingham University grounds manager Ian Cooke said: "Has Monty lost the plot? Does he think gardeners will take his suggestions seriously when we have a wonderful palette of exotic plants from around the world that seem to thrive in our unpredictable climate?"
Guy Barter, of the Royal Horticultural Society, said: "The RHS suggests that a range of native and non-indigenous garden plants are good for wildlife. There is no reason to restrict yourself to native plants, of which there are rather few. In fact it's essential for wildlife to have a healthy mix of native and non-native plants."
And why? It won't save the planet, it would just make our lives so much poorer. Just to satisfy the ego of this over-opinionated TV presenter? Most definitely not a real gardener!
Sorry if I shouted a bit there, but I do feel so passionately about the many styles of gardens we have created over the centuries, and, of course, the role of Cannas, a non-native plant, in those gardens.