Sweet Potatoes are such a useful plant that every Hawaiian garden should have some growing. They are very prolific, easy to grow and have been cultivated in the islands since before Captain Cook’s arrival.
To grow sweet potatoes, you’ll need a sunny location, well drained soil, a little bit of compost, sweet potato cuttings and light to moderate amount of water. As long as you plant them in the right location, sweet potatoes should be VERY easy to grow.
Sweet potatoes, or u’ala, are a very important crop in the Hawaiian culture, second only to Kalo. This food crop is found in many Hawaiian stories of old, mainly having to do with the stinginess of the people. Don’t be stingy, find some room for sweet potato in your Hawaiian garden.
Related: When it comes to harvesting sweet potatoes, having a tool to make the job easier sure will save the back. I have found a garden fork that damages the roots a lot less than the normal garden forks do. Best of all, you can have it shipped right to your door through Amazon.
How to Grow Sweet Potato in Hawaii
BEST CLIMATE
Sweet Potatoes love our warm Hawaiian climate. They grow best up to 2000’. It is considered drought tolerant, but needs a decent amount of water during the first couple months of growth. An area with 30”-50” of rainfall is ideal. I live in an area with more than 100” of rainfall per year and it grows great. That’s because they are planted in very well-draining, almost sandy soil.
WHEN TO PLANT
The best time to plant sweet potatoes for most locations in Hawaii is March thru May. Lower yields occur in plants that have been sown October thru December because of shorter days and more rainfall.
According to the Hawaiian Moon Calendar, the best moons to grow U’ala are on the Ku moons, waxing moon days beginning 2 days after the new moon and all the days between 2 days before and 2 days after the full moon.
PREPPING SOIL
Sweet potatoes love well drained soil with moderate fertility. Poorly drained soil will reduce the yield and produce poor tubers. Too much fertility and you get jumbo, rough, cracked tubers. If you have good soil to grow in the ground, try building up furrows to plant your sweet potatoes into. This will increase drainage.
You may see sweet potatoes growing in very rocky soils. Sweet potatoes are resilient, but in this instance, you may not get tubers. If you have very rocky soil or clay soil, you may want to build raised beds or plant sweet potatoes in pots.
PLANTING METHODS
Sweet potatoes are typically planted by branch cuttings. It is said the best branches to take cuttings from are the smaller, uglier branches rather than the large luxuriant ones. The former will produce large tubers while the latter will provide more green growth.
Take the cuttings that are no more than 2 days old and plant in furrows, 12” between plants and 4’ between rows. If they are to be irrigated plant straight down, if rainfall is the primary source of water plant at a 45 degree angle. The angled planting allows for larger roots at the surface where the plant can access the rainfall. Plant 4 nodes deep to maximize root development.
FERTILIZATION
Sweet potatoes have a relatively low demand for Nitrogen and a high requirement for Potassium. Avoid planting in soils that had recent manure applications as this may cause disease. One to two months before planting, add Agricultural Lime to the soil to balance the pH.
Sweet Potatoes are a great crop to grow after a heavy feeder such as corn or squash.
WATERING
Sweet Potatoes LOVE water in the first 60 to 90 days of growth during tuber formation, but after that, water sporadically. In fact, about a month before harvest, eliminating water and allowing the soil to dry out is best for optimal tuber production.
Related: Perennial Vegetables: Edible Plants for a Hawaiian Garden
Pests to Watch Out For
There are certain pests that love sweet potatoes, but for the most part sweet potatoes are a pretty resilient plant. Root nematodes probably pose the most risk for your sweet potato crop. If root nematodes are a problem for you, it might just be best to think about planting your plants in another area of the garden or in pots.
Caterpillars also love sweet potatoes. There is old lore in Hawai’i that states that it is fair to ask the caterpillar to eat its fill, just leave the root for the farmer. If you are greedy and kill all the caterpillars to keep all of the sweet potatoes for yourself, you are inviting trouble, so please share.
Chinese Rose Beetles have been known to munch the leaves of your sweet potato plant as well. Normally the infestation of the rose beetle is mild, but occasionally they can do some serious damage. Pick them off by hand or use a mild insecticidal soap to help control their population.
How To Harvest Sweet Potatoes in Hawaii
Sweet potatoes are a great plant for the garden because you can harvest not only the tubers, but the leaves as well. The leaves are packed with vitamins and minerals. They are a great green to add to your diet in the tropics.
To harvest the sweet potato leaves, pick from the newest growth tips as these leaves will be more tender. Prepare them as you would for spinach or any cooked green.
To harvest the tubers in Hawai’i, it takes about 4-6 months for the tubers to reach marketable size. If you live in a dry area and were able to cut back on the water the previous month, then your sweet potato greens should be dying back, but if you live in a wetter place, your plant may be just as healthy looking as it did in its first or second month.
For that reason, I like to write down on a calendar when I planted the sweet potatoes so I can have an idea of when it would be a good time to harvest. If you wait too long, you run the risk of the tubers getting attacked by sweet potato weevils.
Dig the roots out of the ground with a spade or garden fork, being careful not to damage the roots. Let them dry out in the shade and then remove all of the dirt from them by rubbing with your hands, do not use water which can cause fleshy tubers.
Typically sweet potatoes are ready to go at this point, but if you want to prolong their shelf life for longer storage you can cure them. Curing the sweet potatoes happen in a covered space with good ventilation that is roughly 85 degrees and 90%-95% relative humidity (RH) for 5-7 days. Then you can store them at 60 degrees.
Properly stored roots can be stored for about 4-6 months after harvest.
The tubers will not store well if you harvested them in wet soil, if they were allowed to get under 50 degrees for more than 5 days after harvest or if the roots are not properly cured.
Related: How To Grow Cucumbers in Hawai’i
History of the Sweet Potato in Hawaii
The sweet potato has a long history in the Hawaiian Islands. They were cultivated on every major Hawaiian island before the arrival of Capt Cook. No one knows how the Hawaiians got their hands on the sweet potato because they originate in South America, but it just goes to show how well the Hawaiians mastered travel by sea. There is much evidence that the Polynesians voyaged to South America long before the Europeans even knew it existed.
The people of ancient Hawai’i grew almost 200 different varieties of sweet potato, but only a few still exist today. Growing sweet potato was one of the few agricultural ventures that were shared by both men and women.
It was the number one plant to grow in times of famine. It provides a high concentration of nutrients in only 4-6 months time.
In the old days, sweet potatoes were used medicinally to induce lactation during pregnancy. Other varieties were used to aid with asthma. Raw tubers mixed with Ti stems were used to aid in vomiting when necessary.
Kamapua’a, the pig god, is the god of the sweet potato. The god has a pig like snout that is perfect for rooting out sweet potatoes.
Whether you root out sweet potatoes with a spade or your nose, make sure you enjoy the harvest of this most amazing plant. Sweet potato deserves to be found in every local garden. Happy growing!!
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