Long summer days stimulate the flowering of many fragrant ginger species. Visitors to our islands frequently comment on how sweet our air smells with the abundance of flowers in bloom. Many ginger species may be given credit for this effect.
Hawaii is blessed with a vast array, and we use them in the landscape for many reasons. These colorful flowering plants add visual beauty. They are useful for leis and flower arrangements, but an added advantage is that many are fragrant. Moist humid tropical climates have the potential for volcanic eruptions, rot and decay so to mask unwanted odors, fragrant flowering plants are ideal. Gingers are among the easiest plants to grow for this purpose.
Pharmaceutical companies have been studying the ginger family in recent years and found that many have medicinal qualities. Edible ginger or Zingiber officinale, has been used for thousands of years as a medicine. Polynesians brought turmeric (olena) as they traveled throughout the tropical Pacific. Cardamom and many other plants are used as spices but were originally used as medicines and have antioxidant properties. The ginger used in Thai cooking is galangal and we must not forget the awapuhi kuahiwi, or soap ginger, that early Polynesians brought to Hawaii many centuries ago.
The ginger family is noted for its many colorful and fragrant species. Gingers are related to the banana, palm and bamboo families in that they are monocots. Many come from Malaysia, Indonesia and other parts of tropical Asia.
There are around 50 genera and over 1300 species in the family, the majority of which are native to tropical regions of the eastern hemisphere. More are being discovered every year. Most genera are well adapted to Hawaii’s varied climates. Many grow in the tropical zone, but some will thrive at 6,000 feet or more of elevation.
Gingers are rhizomatous perennials, generally with simple above-ground stems. Flowers vary considerably, from small to very showy, and are usually borne in heads. Flowers and foliage of many species are excellent for use in floral arrangements. Gingers are relatively easy to cultivate, and once established require little care. They grow well on a wide range of soil types, as long as the soil is moist.
Handle gingers the same as bananas. They do best in moist soil high in organic matter. An application of fertilizer in early spring when active growth begins, and two more applications at the same rate during the growing season will be sufficient. The fertilizer applications should be spaced eight weeks apart. Also, compost and well-rotted manures applied every 3 months will help keep the soil sufficiently rich. Planting or transplanting can be done at any season of the year. The parent clump may be divided like any rhizomatous herb. The fleshy underground rhizome may be severed at any point, as long as each piece has at least one good eye to produce a new plant.
Here are some other gingers to consider for your garden. Torch ginger, shell ginger, white ginger, yellow ginger, red ginger and Tahitian red ginger are just a few that you will find at local nurseries. The butterfly-lily, or white ginger, with its heads of white butterfly-like flowers is commonly found growing wild. The extremely fragrant flowers last but a day and are constantly being replenished by a new supply. The flowering period will last for several months. Although common in the wilds, this is still one of the best for garden fragrance and lei flowers. The yellow ginger (Hedychium flavescens) from India is another fragrant species common in wet forests and along east Hawaii roadsides.
The shell ginger with its 3- to 8-foot stalks of evergreen foliage is used more frequently in sunny, drier conditions than most gingers. Its flowers, with their combination of cream, yellow and red markings, are excellent material for floral arrangements. Leaves are used to dye cloth and as a tea in Japan. Other gingers to consider are the Costus or spiral gingers. There are many species and varieties. The orange flowered Himalayan ginger, Hedychium greenii, sometimes called the guava jelly ginger is tolerant of cooler regions. It is so cold hardy that it will winter over as far north as Seattle and Victoria, British Columbia if given protection. Usually an application of mulch before the first frosts is sufficient. Kalo and two species of hardy banana — Musa bajoo and Musa sikkimensis — may also be grown in similar climates with mulch applied to protect the rhizomes from freezing.
Take note that Kahili ginger (Hedychium gardnerianum) tends to form seed that can be easily spread. It is now found in many moist Hawaiian forests up to 6,000 feet elevation. Although it has attractive fragrant flowers, it is not recommended to be planted in Hawaiian gardens.
For further gardening information, you may call the University of Hawaii Master gardening hotline. In Kona the number is (808) 322-4893 and in East Hawaii call (808) 981-5199.
Norman Bezona is professor emeritus, University of Hawaii College of Tropical Agriculture and Human Resources.