Agriculture minister Senzeni Zokwana said on Friday the drought-striken nation needed to import between 5 and 6 million tonnes of maize.
Hot weather and poor rainfall have ruined a third of the maize crop as the country faces its worst drought in decades after the driest calendar year since records began in 1904.
Zokwana said maize imports, which would start as soon as May, were "urgent".
"We have to make sure that we don't wait until it is too late," he told a news conference in Pretoria after meeting industry players.
Economists have warned that imports would push up food prices and affect millions of South Africans who are already feeling the pinch because of a struggling economy.
Agriculture contributes 2.2 percent to economic output, but a major farming slowdown could tip the economy into recession as well raise the unemployment rate of around 25 percent.
The government, which has been accused of ignoring warnings that a drought was imminent, will offer farmers soft loans to help them through the hard times, Zokwana said.
He dismissed claims South Africa did not have the infrastructure to handle mass maize imports.