During the week Mint Cafe, and possibly others, will also encourage customers to ask for their kapu ti or kapu kawhe in te reo Māori.
Te Wiki o Te Reo Māori was an important way to stop the language from dying, Ponga said.
He said it was becoming a language that introduces protocols and customs more than a living language in everyday practice.
"Now is a critical time for us to activate our resources and promote te reo Māori initiatives that are going to sustain us into our future."
Last week she and other staff from Te Wānanga were at the annual Pae Rangatahi celebrations in the Whanganui War Memorial Centre, where Whanganui primary-aged children showcase their kapa haka.
"They're using the vehicle of the language to bring all these skills to fruition," she said.
"Those children will be the caretakers of our language moving forward."
Te Wānanga is the main organisation teaching te reo Māori in Whanganui. It has about 200 language students - with about 50 in immersion classes and the rest in language acquisition classes.
The immersion classes are for people who already have a basic understanding of te reo, and they push learning along faster.
Those learning te reo are a broad mixture. Only about 30 per cent are Māori, with the rest a mix of ethnicities. One of them is Whanganui Mayor Hamish McDouall.
Some want to become fluent, while others want an understanding that will help their relationships with grandchildren, nephews and nieces.
There have been larger numbers of young people recently, Ponga said, and next year there will be an extra immersion class working at a higher level, with more grammatical structures.
The tauira (students) don't have to pay fees, and are given books, CDs and other resources to help their learning.
During this week students in some classes will be taught only in te reo Māori, then revert to delivery in English when the week is over. Others may go further, ordering their hamburgers at McDonalds and writing their emails in te reo as well.
One staff member had set a time where anyone is welcome to sit with a group at Trafalgar Square and talk in te reo. He hopes to continue with this.
Māori language is gaining ground, Ponga said, but there's a long way to go.
"We still have a lot ahead of us in terms of appreciation from our partners and the community."
