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.
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.
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.
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.
Kūmara gardens were known as māra kūmara. They consisted of puke (mounds) formed from loosened soil, arranged either in rows or in a recurring quincunx pattern (the shape of a ‘5’ on a dice). Kūmara tubers were planted in the mounds. Sloping land with a sunny, northerly aspect was considered ideal.
Relatively light, sandy soils were preferred for growing kūmara. In areas with heavier soils, people added gravel and sand – sometimes moving these materials long distances to very large gardens.
It is thought that the gravel and sand allowed better drainage, so crops could be planted earlier because the drier soil warmed up more easily – or that the sun warmed up the stones and warded off the damaging effects of frost.
In some areas, the remains of extensive gardens can be seen, with rows of stones that are thought to be boundary markers. In some places stones are piled into mounds instead of rows, and in others there are both mounds and rows. It is not clear what their function was. Crops may have been grown in soil on top of the rocks, which helped regulate the temperature. Alternatively, the mounds and rows may have been left when garden areas were cleared, with crops planted in between.
Simple fences were built around gardens to act as windbreaks and keep out pūkeko birds. Kūmara were attacked by caterpillars of the sphinx moth (kūmara moth), and Māori often tamed seagulls to eat the caterpillars. Sometimes fires were lit and kawakawa leaves thrown on to smoke out the caterpillars.
Kūmara could be grown in one place for only a limited time before soil became depleted of nutrients. Another garden had to be started elsewhere and the original left fallow so the soil could regenerate. In tropical Polynesia, rotational cropping could be easily maintained over a 20- or 25-year cycle that eventually returned to the first garden plot. However, in New Zealand, bracken fern often colonises bare land, forming a tangled web of stems and roots which is difficult to eradicate. The plant was hard to dig up, and burning did not work, as it regrew from the roots. Kūmara gardens that had been used earlier became largely unusable because of bracken. New plots had to be found, and suitable land eventually became a diminishing resource.
In 1969, a New Zealand-based collection of hundreds of kūmara varieties was sent to Japan for safekeeping. In 1988, on a trip supported by British botanist David Bellamy, members of the Pū Hao Rangi trust brought nine cultivars back to New Zealand. Three of these – taputini, rekamaroa and hutihuti – may date from before European arrival in New Zealand. DNA analysis is being used to study their provenance.
In the 19th century, traditional kūmara grown by Māori were quickly superseded by larger and higher-yielding sweet potatoes from North America, brought by sealers and whalers. New Zealand’s commercial kūmara crop is based on three more recent cultivars, the Owairaka Red, Toka Toka Gold and Beauregard, all of which produce tubers about 20 centimetres in length.
In the early 2000s, there were about 85 commercial kūmara growers, mostly in Northland. Around 20,000 tonnes were produced annually from 1,220 hectares of plantings, mainly for domestic consumption.
Māori developed a number of tools for gardening:
After they were grown over summer, kūmara tubers were harvested around March. They would not grow in winter, so the tubers had to be stored and preserved. Polynesians already had a tradition of storing certain crops in subterranean pits – a technique which worked in New Zealand with kūmara. Underground storage provided the high levels of humidity needed to preserve the tubers so that some could be eaten over winter and some planted out later.
After potatoes and other vegetables were introduced to New Zealand, kūmara became less important to Māori – but it was still popular. The rest of the population didn’t catch on until the Second World War. American servicemen stationed in New Zealand who missed sweet potatoes from home took to kūmara. Many Pākehā followed suit.
The remains of kūmara storage pits, or rua kūmara, are still found around the country. Many types of pit were developed, and there is some evidence that different tribes preferred particular types. Pits included small rectangular holes in the ground, inter-connected cave-like pits found on flat land and on the sides of banks and hills, and large semi-subterranean rectangular roofed pits.
After being sterilised with fire, pits were sealed with small wooden doors that kept out vermin and the elements.
Small tubers were scraped, then dried in the sun to make a delicacy called kao. They were eaten raw, or soaked and mashed, or steamed in a hāngī (earth oven).
Larger tubers were prepared in a variety of ways:
The other food plants introduced from Polynesia proved difficult to grow in the new environment, so kūmara was increasingly important to Māori communities. Its importance and value rose further as the availability of suitable land for gardens diminished. Much of the activity to produce kūmara became ritualised – it was even associated with Rongomātāne (Rongo), a high-ranking atua (god). Rongo was also the god of peace, which may reflect the importance placed on kūmara gardening compared to fighting and warfare.
In one tradition Pani-tinaku brought kūmara to earth. Her husband was Rongomāui, the younger brother of Whānui (the star Vega). He stole the kūmara and gave it to his wife, who gave birth to it. As a curse, Whānui sent down Anuhe, Toronū and Moko, all names for the kūmara moth caterpillar, which attacks the leaves of the plant.
Before planting the main crop, there was a ceremonial kūmara planting known as the māra tautāne. This took place away from the main crop, and the tubers were set apart for the atua.
When the main crop was planted, karakia (prayers) were said, and an offering was made to placate the gods – usually a bird. Tapu (spiritual restriction) was invoked by the tohunga (priest), and remained in force until harvest. This kept people away from the gardens.
The harvest of the kūmara was highly ritualised. The tapu was lifted in a ceremony called the pure. The first fruits were set aside for the gods, usually Rongo, and a hākari (feast) was held.
Kūmara featured in some whakataukī (proverbs). Important chiefs with many followers were sometimes described by saying, ‘E tupu atu kūmara, e ohu e te anuhe’ (as the kūmara grows, the caterpillars gather round it). Another well-known saying, 'Kaore te kūmara e kōrero mo tōna māngaro' (the kūmara does not speak of its own sweetness), encouraged people to be modest.
The mauri (life force) of the kūmara crop was often protected by certain talismans. These included taumata atua – stone images representing atua, Rongo in particular. There were also atua kiato – wooden pegs with carved heads, which were inserted into the ground. Sometimes skulls or preserved heads were put on a post to preserve the mauri of a kūmara crop.
Best, Elsdon. Māori agriculture: the cultivated food plants of the natives of New Zealand: with some account of native methods of agriculture, its ritual and origin myths. Wellington: Te Papa Press, 2005 (originally published 1925).
Davidson, Janet M. The prehistory of New Zealand. Auckland: Longman Paul, 1987.
Leach, Helen May Keedwell. 1,000 years of gardening in New Zealand. Wellington: Reed, 1984.
This 1967 article from Te Ao Hou magazine discusses ways of growing and preparing kūmara.
A 1962 article from Te Ao Hou about the religious aspects of growing kūmara.
This very comprehensive report by Louise Furey focuses particularly on kūmara (PDF, 445 KB).
This 1880 paper by William Colenso includes information on kūmara.