The son of former Swansea head coach and All blacks and Ireland assistant coach, John, the 23-year-old back rower has a Welsh qualification having been born in Swansea.
He had been playing Super Rugby for the Blues in Auckland and for Wellington in the Mitre Cup. He played against Wales for New Zealand at the 2019 World Rugby U20 Championships, ending up on the losing side in Argentina.
The Welsh side that day contained three of his new Scarlets teammates, Morgan Jones, Kemsley Mathias, Ryan Conbeer and Sam Costelow.
“Taine is an athletic, versatile forward who is able to play across the back row. We have been impressed by what we have seen of him with Wellington and when he has featured for the Blues in Super Rugby,” said Scarlets head coach, Dwayne Peel.
“He is a player of huge potential, and we are excited for him to join the young generation of Scarlets who are coming through the ranks here. I’m sure he will fit in well with the style of rugby we like to play and we’re looking forward to welcoming into the group ahead of the new season.”
Plumtree becomes the latest addition to the Scarlets squad for the 2023-24 campaign following the signings of Ioan Lloyd from Bristol, Tomi Lewis from Jersey, Alex Craig from Gloucester, Teddy Leatherbarrow and Charlie Titcombe from Loughborough University and RGC 1404 scrum half Efan Jones.