Friday | December 15, 2017
About Us | Contact | Subscribe

Hummingbirds and sweet potatoes

Can you eat the leaves of the local sweet potato? Plus do hummingbirds pollinate veggies? And if I bought bees, and let them loose in my area, would that be a good thing or not? — W.

A. Yes, both the leaves as well as the tubers of the sweet potato plant are edible. In many varieties, the leaves as well as the roots are good sources of vitamin A and C, in addition to protein, riboflavin and phosphorus. The raw leaves contain larger amounts of some nutrients than do the cooked leaves. Although difficult to find in the supermarket, shoppers can often purchase sweet potato leaves at the local farmers markets.

B. As for the hummingbirds, I am having difficulty finding specific vegetables that hummingbirds pollinate. That’s probably because there are not many vegetables with red, tubular shaped flowers, which hummingbirds are most attracted to.

Only about 25 percent of plants are able to exchange pollen by wind. The rest rely on pollinators to do the job. In addition to bees, bats, beetles, butterflies and other birds, hummingbirds are important pollinators. They feed about every 10 minutes all day and consume up to 2/3 of their body weight by extracting nectar; they can service 20 flowers per minute. Their wings, beating up to 55 beats per second, allow them to fly at speeds up to 50 mph. They can hover and even fly backwards or upside down.

They are primarily attracted to tubular flowers. Hummingbirds are stimulated by color, especially the color red. Clumps of bright red, orange and pink flowers are more visible to them than other colors. Plants with red, tubular shaped flowers are an excellent choice to plant in the garden. Other plants that attract hummingbirds are gladiolus, honeysuckle, iris, lupine, nasturtium, petunia, penstemon and cosmos.

C. The problem with purchasing bees is they will not stay confined to your property. Planting flowers to attract the bees is a better idea. There are numerous websites which list the many plants which attract bees.

Hi, Nick. Someone told me to put the chicken manure pellets in the crowns of the hapuu ferns. Do you think that could cause fertilizer burn, as happened to mine? Thanks, Joan

Yes. Chicken manure, as well as other fertilizers can potentially cause a burn; of course, it will depend on the amount used. But placing the material in the crown, that is, in direct contact with the plant is risky. Chicken manure will also burn roots, again depending on the amount. But at least, when applied in the ground, the soil will act as a buffer giving some cushion to an accidental overdose.

I live in Glenwood and have a grapefruit tree. It’s over 10 years old and I have been harvesting fruit for a number of years. Here is the problem: I have never had a really sweet piece of fruit. Is there some fertilizer I can apply or is there another way to sweeten the fruit?

Of all citrus varieties, grapefruit requires the most heat in order to develop sweet fruit. Where are commercial grapefruit orchards located? In the very hot regions of California (desert), Texas, Arizona and Florida. There is no fertilizer that will do

the trick; unfortunately it is just not hot enough at the higher elevations of the Big Island. Leaving the fruit on the tree as long as possible is the best way to raise the sugar content. To a degree, they will sweeten the longer they hang on the tree, but there is a point where fruit quality will begin to deteriorate.

For a detailed discussion on sweetness in citrus fruit, go to where you can read two articles on this subject:

“What Factors Determine Sweetness in Citrus Fruit?” and “Sweetness in Citrus.

Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at


Rules for posting comments