Thursday, August 31, 2017

Growing Sweet Potatoes

 
 
Sweet potatoes are native to the tropics and need warm sunny conditions in order to grow.
In Hawaii they can be planted at any time during the year.

Sweet Potatoes Growing in Smart Pots
 
 It would seem that sweet potatoes should be easy to grow in Kihei but after three years I still haven't mastered them. Although they will grow during the hot summer months, my best results were from slips that were planted between October and December and harvested in the winter/spring. Sweet potatoes need at least four months to grow large enough to harvest.
 
Hanna Sweet Starting to Flower
 
Sweet potatoes are grown from slips - the vining leaves that sprout from a sweet potato that's placed in water. They can be ordered online in the late spring or you can grow them yourself. The problem I encountered when purchasing online was that there were countless names I had never encountered at the market. Unfortunately, the slips I chose produced tubers that were starchy rather than sweet and it was a waste of money.
 
Japanese Purple
 
Some varieties need a lot of space to vine and don't grow very well in containers. Because I'm growing them in 15 gallon Smart Pots, most of the sweet potatoes I've harvested weren't very large even when I let them grow for 6 months.
 
So far my best results were with Japanese Purple (also called Japanese Red). They can be purchased almost anywhere on Maui. They seem to be very adaptable to containers. The orange sweet potato I grew was one with no name from Whole Foods. I haven't been successful growing Garnet - the Thanksgiving favorite - I'm not sure why I can't get them to grow but I'll keep trying.

Unless you're familiar with a wider range of sweet potato varieties than are typically available on Maui, I recommend growing your own slips from your favorite varieties available locally.

Pickleworm Damage
 
In my garden, pickleworms, slugs and snails were the problem pests. The pickleworm is active during the summer months and they will dig under the soil and eat the tubers. The snails and slugs eat the leaves which wasn't a big problem until this year when Rat Lung disease became an issue on Maui.

Sweet potatoes when grown in the ground can be very invasive - similar to horseradish or mint. After I harvest them from the containers I don't have to replant slips as they will regrow just from the stringy roots that remain in the soil.
 

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