Uala - Sweet Potato

SUBHEAD: An important staple food of Hawaii.

By Linda Pascatore 31 December 2008 for Island Breath -

Image above: photograph of flower of sweet potato by Forest & Kim Starr. From (

Uala, or sweet potato, was a canoe plant brought to Hawaii by the Polynesians. The sweet potato, or Ipomoea batatas, is a member of the morning glory family. It was an important staple food in Hawaii.

The plant has heart-shaped five lobed leaves, and small pink-lavender flowers similar to the morning glory. The vine is purple or green, the leaves dark green, and the flowers purple/lavender. It is a perennial, and spreads and creeps along the ground, and produces root vegetables. Different varieties produce sweet potatoes in various colors; purple, red, orange, yellow, and white. The skin and flesh are often different colors.

A white skinned tuber may have purple flesh, or a purple skinned potato have yellow flesh. This plant originated in Central or South America, where it was cultivated 5000 years ago. From there it spread throughout the Caribbean.

During later invasions of South America, the Portuguese and Spanish found the sweet potato, and dispersed it throughout Europe and their colonies. Somehow, it appeared in Polynesia, at least 500 years before western contact. The theory is that it was carried to the Polynesia by migrating birds, or even possibly accidental drift of a lost raft or boat off the South American coast.

Sweet potatoes are only very distantly related to potatoes (originating also in South America) and yams (originating in Africa). There is evidence of cultivation of the sweet potato in Hawaii from at least 1000 AD. Ulala was especially abundant in Niihau, where it was eaten more frequently than taro.

This is probably because the drier conditions in Niihau are more conducive to sweet potato, than taro which requires more water. Over 200 varieties of this plant were found in Hawaii. It can grow from sea level to 5,000 feet elevation, and will grow in poor soil. Each plant can yield over one pound of potatoes. Most varieties produce in three to seven months after planting.

Image above: the Leaves of sweet potato leaves on ground crawling vine.

Uala is best cultivated from slips of the plant, which are replanted. The slips should be cut about 6-9 inches from the end, with the growing tip remaining intact.

Since this is a vining plant, it is good to put them in mounds or the edges of a garden, because they will spread out significantly. Soil that is loose or loamy will facilitate the growth of large tubers.

When harvested, the tubers should be dried or cured for a week before consuming. In Hawaii’s climate, they do not need to be harvested all at once, but can be left in the ground until needed. We recently obtained purple Molokai sweet potato starters from a friend.

So far, they have been an easy plant to grow, not requiring much care. We are waiting for our first harvest. We did have some wild pigs in our yard, who were very interested in the sweet potatoes. They rooted around them, and did a little damage. Interestingly, Kane Pua’a, or Kamapua’a, the pig man, is the god of the uala.

The ulala is considered a good plant for famine conditions, since it is so quickly producing the easy to grow under a variety of conditions. In areas of Asia which are plagued by tsunamis, it is often the first crop that is replanted after the storm.

In Hawaiian, there was a saying: He ‘uala ka ‘ai ho’ola koke i ka wi.

The sweet potato is the food that ends famine quickly. Uala tubers can be baked, steamed, or boiled. Sweet potato poi can be made by boiling, peeling, and mashing. The leaves are also edible. Sweet potato can also be fermented into an alcoholic drink, uala awa awa.

Polynesians had many medicinal uses for uala. It was used as a tonic for pregnant women, for asthma and congestion, to induce lactation, as a gargle for a sore throat, and as a laxative. Raw uala mixed with ti leaves could induce vomiting. All parts of the plant were also used as feed for livestock, especially pigs.

In China today, sweet potatoes are cultivated primarily as pig fodder. Compared to other vegetables, the sweet potato ranked highest in nutritional content, and is a better source of complex carbohydrates, protein, Vitamins A and C, iron, and calcium; according to a study at the Center for Science in the Public Interest. They are also considered a good food source for diabetics.

So, if you have not been eating uala regularly, it is time to try this sweet, and nutritious vegetable. In Hawaii, you can easily find several varieties of the vegetable at farmer’s markets, and in local supermarkets. We usually bake them in the oven, but have also made sweet potato fries, ot boiled and mashed them with a little milk. They are a filling comfort food, which is also delicious and good for you.

Note: For previous articles on flora and fauna select "Hawaiian Nature" from "Archives Menu".

See also:
Island Breath: The Gecko: Our Little House Guardians 9/7/08


Anonymous said...

Does this plant grow better in the sun or shade?

Juan Wilson said...

We have found a partially shaded area works for us. We are on the dry sode of the island (Hanapepe) and the shade may keep the moisture in the soil better.

Probably having the right consistency and chemistry of soil is a more important attribute.

Sara said...

I need to know how long before I can pull my molokai sweet potatos?

Anonymous said...

I live in Manoa, so the soil is clay and it's very wet. Is it possible to grown Uala in these conditions?

Liko said...

I live on the windward side of Maui and have sandy soil. I'm wondering how the Uala would do in these conditions? My hope is to use it as a ground cover edible landscape alternative to beach morning glory. Mahalo.

Juan Wilson said...

Aloha Liko,

As long as it has the nutrients it needs the sandy soil should be excellent. The roots can really spread out. I've added river sand to my taro beds because the clay soil clamps the roots. My cassava goes better in sandy soil too.

Anonymous said...


I have been trying to grow three different varieties of 'Uala (given to me by a farm) in a 2ft x 3ft plastic pot. I can't put 'em in the ground here because it's a rental and the yard gets treated for bugs every month with some crazy insecticides. I recently re-potted my 'Uala and it's been the third month since I received the plants. There are no potatoes and no growth yet. They had flowers when they were given to me but all have fallen off and it has not produced any new flowers.

They've been struggling to survive ever since I got them; the leaves turn yellow after a few weeks and fall off before new leaves start sprouting. They also have crusty white stuff under the leaves which I think are aphids or whiteflies, maybe even papaya bugs.

Does anyone know the watering schedule for 'Uala and how I can control the bugs safely? Should I use a special soil?


Anonymous said...

Can you post more info on U`ala because im in a gardening club and im studying U`ala

Anonymous said...

Like for example apicture of the parts or where you can get them etc. PLEASE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Anonymous said...


Linda Pascatore said...

I wrote the original article on Uala from information I found on the internet from a simple google search. We did try growing some here on Kauai from cuttings of plants that people gave us. They grew fine, lots of leaves, but never formed sweet potatoes. We tried both a sunny and a shady spot, but as yet have had no luck. I believe you may need softer, looser soil so that the root bulbs may form. So, I really don't have much more info to share with you. Sorry!

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