Caregivers, nurses and service workers at the biggest rest home chain in the country will go on strike on Thursday over pay.
The workers at Oceania announced the strike action after mediation talks on Friday "failed to produce a solution".
Up to 1500 members of the Nurses Organisation and the Service and Food Workers Union Nga Ringa Tota will join the two-hour strike from 8.30am.
Joint union spokesman Alastair Duncan said the strike was timed to minimise any impact on residents.
"Residents and families are supportive of the workforce but management appear deaf to their concerns," he said.