"This has to end. It has to stop. Let Ceri be the last - let her be our lesson. I need to tell our kids it's okay to feel whatever they want to feel and that they have to speak out, they have to say something," she said.
Ms Cairns, who also has two young sons, said Ceridwen had gone to live with her father Julian Allom in Christchurch two months ago, and enrolled at Riccarton High School.
She said their relationship had become volatile earlier this year and Ceridwen needed to move, but her last conversation with her daughter was happy and positive.
"There was giggling too. She had started her first schoolyard romance and he was an absolutely lovely kid. Before we hung up I told her 'I love you, baby'. She said 'yeah, I know'.''
Her body was discovered the next morning.
Ms Cairns said her daughter had a history of self-harm.
She also adored animals, drama and music, and had a quirky sense of humour and take on life.
She had volunteered to help out at a Masterton vet service and had distinguished herself as a hockey player, actor and singer at St Matthew's Collegiate.
"But she was down on herself as well because of her need to be accepted. She never felt like she was keeping up with her friends even though she was so pretty and so talented.''
St Matthew's Collegiate principal Erik Pedersen said Ceridwen was "a bright and bubbly girl who had everything going for her'' and late last year had won a scholarship to continue studying at the school.
He said Ceridwen's classmates had been counselled in the wake of her death, parents had been informed and the school chapel was opened for pupils.
Riccarton High School principal Phil Holstein said the Christchurch school had also offered counselling to classmates affected by the death and had held a memorial service for Ceridwen at Spreydon Baptist Church in the city on Saturday.
