Monty Don visits the world's 80 most inspiring gardens. At Cape Town's famous Kirstenbosch Botanic Gardens he sees the king protea, South Africa's national plant. In the Drakensberg Mountains he sees some native flora in its natural environment. His favourite garden is a school vegetable patch in Thembisa, one of Johannesburg's townships. Monty is intrigued by how gardening styles have changed here since the Dutch first settled in the 19th century.