The Polynesian ancestors of Māori introduced kūmara (sweet potato, Ipomoea batatas) to New Zealand in the 13th century. They also brought other tropical food plants for cultivation, including taro, hue (bottle gourd), uwhi (yam), and tī pore (a tropical variety of cabbage tree). The aute (paper mulberry) tree also arrived; its bark was used for making tapa cloth and was not eaten. All of these were seen growing in the Bay of Islands by British navigator James Cook in 1769.
It seems likely that the kūmara had earlier been taken to Polynesia by Polynesians who had voyaged to South America.
Adapting to a new environment
Gardening conditions in New Zealand were very different from the small tropical islands in east Polynesia. Northland’s climate most closely resembled that of Polynesia; Southland was the most different and difficult place to try to grow these tropical plants.
In Polynesia, kūmara grows all year round, and is propagated by planting the shoots from the edible part of the vegetable. In New Zealand, however, winter is too cold to grow kūmara – and even in summer it will not grow in some areas. Also, kūmara has to be grown from tubers instead of from shoots.
Māori adapted their growing regime so kūmara could be stored over winter and the tuber planted out in summer. It could only be grown in the warmer parts of the North Island, and coastal areas of the northern South Island. Banks Peninsula was its southern limit.
Kūmara on board
There are different tribal traditions about the introduction of kūmara into New Zealand. Descendants of the people from the Horouta canoe believe that their ancestor Hinehākirirangi safeguarded the kūmara on that canoe, and planted it at Manutūkē on Manawarū. Te Arawa and Tainui traditions speak of the female ancestor Whakaotirangi bringing kūmara to New Zealand.
The first kūmara gardens
Early kūmara horticulture was small-scale. On arrival in New Zealand after weeks at sea, it was critical to get the plants growing in soil before they were damaged. Bush was quickly cleared by burning and gardens were planted – this probably happened in a number of areas around the same time. The settlers would have had to work out that they now needed to plant the tuber rather than the shoots that grow from it.