New Zealand Wine Company went further into the red in the second half of last year.
The marketer of the Grove Mill, Sanctuary and Frog Haven brands lost $1.6 million in the final six months of 2011, 48% more than in the same period a year earlier.
Revenue rose 17% to $7.3 million.
Chairman Alton Jamieson says the 2012 harvest will be affected by bad weather during flowering, and it could yield up to 20% less than initial forecasts.
Grape prices and the strong New Zealand dollar are also adding to uncertainty.