Vegetables prices shot up last month as food prices rose overall.
Official figures show food prices rose 0.7 percent in July compared with June - the fifth successive month of gains.
Vegetable prices rose an average 9.2 percent in the month, while a 500g head of lettuce jumping to $5.42 in July from $3.07 in June, and $3.30 in July last year.
"July was particularly cold and wet in the North Island where a lot of our lettuce is grown," Stats NZ consumer prices manager Geraldine Duoba said.
"Lettuce prices are now at their highest since the series began, and 2.5 percent higher than their previous peak in May 2017."
The other main contributions came from tomatoes, which rose by 30 percent, and broccoli, by 24 percent.
Fruit prices eased, led by seasonally cheaper avocados, which fell by 36 percent, as well as nectarines and strawberries.
On an annual basis, food prices rose 1.1 percent.
Restaurant meals and ready-to-eat food prices jumped 3.2 percent, the highest annual increase since September 2011.
"Large seasonal changes in fruit and vegetable prices tend to lead monthly food price movements," Mrs Duoba said.
"But price increases for restaurant meals and ready-to-eat food have been consistent, and led annual food price inflation this year."