Richelle and Bruce Adams, of Adams Flags, said trade had never been busier since they began their flag-making business in 1996, with a surge of sales before Waitangi Day.
While the traditional New Zealand flag and silver fern remained popular, an increasing number of people were choosing to fly the tino rangatiratanga flag, or the flag of Maori self-determination, she said.
"All the news over flying it on the [Auckland] Harbour Bridge seems to help sales," Mrs Adams said.
Also popular was the United Tribes flag and they were unable to keep up with demand, Mr Adams said.
"A flag brings out special meanings for everyone. People go to war for a piece of fabric."
The company was fielding calls from all over New Zealand, and recently supplied the United States flag to McMurdo base in the Antarctic.
While New Zealand was yet to reach the flag-waving fervour of Australia and the United States, it was becoming more common for people to fly their respective colours.
"We are catching up on what the rest of the world is doing."
While Waitangi Day was a popular day to display flags, one of the best sales periods came from a different nation's celebration.
"We always do well out of St Patrick's Day."
•Awarua runanga will host Ngai Tahu Treaty of Waitangi Day commemorations at Te Rau Aroha marae, in Bluff, tomorrow.
The day will begin with a powhiri at 10am and a message from the Governor-General, followed by a presentation of the Titi Island restoration and poha demonstration (demonstration of traditional kelp storage techniques) before lunch and special demonstrations.
The Treaty of Waitangi was signed on Ruapuke Island, in Foveaux Strait, in 1840.
Ruapuke Island is one of three locations in the South Island where Ngai Tahu signed the Treaty of Waitangi and commemorations alternate each year.
Last year's commemorations were held at Otakou marae on Otago Peninsula.
