Olga Merewhati Kuti (38), shed-hand, admitted injuring the child with intent to injure on April 28.
The boy's name was suppressed by Judge Phillips, as was the town in which the incident occurred.
A police summary stated Kuti became angry with the child and struck him about the buttocks with a 30cm plastic soup ladle.
As the child attempted to shield himself with his hands, she repeatedly struck his hands and forearms with the ladle.
While he writhed on the floor in an attempt to avoid more blows, Kuti continued striking him about the body and legs.
She then used her hands to hit the boy about the head and face.
The boy was taken to Dunedin Hospital for assessment and placed in the care of Child Youth and Family (CYF).
A paediatrician who assessed the boy found an ear was bruised both internally and externally, he had a bruised and swollen lip, bruising about an eye, bruises to a lower arm and leg and significant, deep bruising on a buttock and outer thigh area.
Kuti admitted the attack to police, stating she had lost control and had since realised she had been cruel to the boy, for which she was remorseful.
She cried as she stood in the dock yesterday.
Judge Phillips said Kuti's life read like a tragedy.
She had six children to her former husband, in a marriage which was a "disaster to say the least", he said.
Kuti was pregnant to another partner, had been under "immense pressure" in her personal life and suffered depression.
"I have sympathy for the defendant's background circumstances but, in my view, there can be only one outcome. That was a prolonged, savage and severe attack on a defenceless child, in which you used a weapon and were totally out of control," Judge Phillips said.
Counsel Tim Cadogan accepted there had been "a beating" but stressed the "extreme and genuine" remorse felt by Kuti.
Judge Phillips said Kuti had previous convictions for matters relating to violence, behaviour likely to cause violence, and resisting police.
Kuti was ordered to complete anger management and counselling when released from jail.
