Fonterra's new Canterbury milk powder plant under construction at Darfield is on track to start processing from August.
Darfield will be Fonterra's first new processing site in 14 years and was planned to handle the increasing milk production in the South Island.
However the cooperative has already decided to triple its capacity with a second drier.
Trade and operations manager Gary Romano says milk production is growing even faster than expected.
Work on the $300 million second drier at Darfield will start in the next few months so it is ready for the 2013 season.
It will have double the capacity of the first drier, processing an additional 4.4 million litres of the region's milk each day.