Victoria's prison population surged under four years of Coalition government, climbing from around 4500 when the Coalition took office to an extraordinary peak of 6100 - the biggest jump on record.

New Bureau of Statistics figures point to a system at breaking point, unable to cope with such a rapid increase. They show Victoria's prison population fairly stable until the late 1990s when it began growing by about 1 per cent per year. It jumped 5 per cent in 2006 and then returned to slow growth until the final two years of the Brumby government when it grew 3 to 4 per cent per year. Under Ted Baillieu it also grew 3 to 4 per cent per year before exploding under Denis Napthine to grow 9 per cent and then an unprecedented 14 per cent.

There will be no young inmates at the Grevillea unit at Barwon Prison from today. Credit:Angela Wylie

Mandatory minimum sentences and tougher parole rules pushed up the number of Victorians in prison from 112 per 100,000 adults to 134 in just two years.

Over the past five years the number of Victorians in prison has climbed 40 per cent, more than any other state. The number of indigenous Victorians in prison has almost doubled, climbing from 240 to 470.