JOHANNESBURG, June 23 -- On his farm two hours north of Johannesburg, Nico Thuynsma gestured towards thousands of orange, yellow and pink proteas in flower and thriving 1,500 kilometres from their natural home at the southern tip of Africa.

"They're all different," the 55-year-old farmer said of the assorted blooms from the diverse Proteaceae family that has more than 350 species in South Africa, from firework-like "pincushion" varieties to delicate "blushing brides".

He picked out a majestic pink and white crown, nearly the size of his head, that has taken four years to reach its impressive size. "The King Proteas are very slow to grow," Thuynsma said.

The largest of the proteas, the King Protea, is South Africa's national flower.

It...