Tomato gardeners and distribution workers will strike on Monday after months of failed negotiations.
Turners and Growers staff will picket outside main sites from 4am for the Living Wage - at least $20.55 an hour.
First Union spokesperson Denis Roche says most workers earn between $16.50 and $18 an hour.
"That's a really low wage for anyone, particularly if you're living in Auckland. They haven't had a pay increase for over a year."
Turners and Growers says it still has a strong relationship with its team and is committed to finding a positive outcome.
"Throughout our discussions with First Union we have been acting in good faith while negotiating collective agreements for some time," the company said in a statement.
Ms Roche says industrial action is a last resort.
"They've just refused to meet with us or negotiate with us about anything, apart from dropping the collective agreement."