The 24-year-old centre-half was initially with the Pilgrims until January 6 — on loan from Skrill Premier leaders Cambridge United — but he will now complete the campaign at The Jakemans Stadium.
Garner has been in imperious form alongside Skrill North player of the month Carl Piergianni — and has netted four goals in 20 appearances to date for the Pilgrims.
Striker Charley Sanders, meanwhile, has joined Evo-Stik Premier Division side Grantham Town on loan.
The 18-year-old marked his debut for the Gingerbreads with a goal in Saturday’s 3-2 defeat at Frickley Athletic — and is with Town on an indefinite basis to get valuable match time under his belt.
Ben Fairclough — who himself spent a month on loan at the Meres Stadium — has returned to the Pilgrims’ squad and was an unused substitute in Saturday’s 2-1 FA Trophy win at Southport.