Warm humid summer days stimulate flowering of many fragrant flowers especially plumeria, angel trumpets, orange jasmine, pikake, night blooming jasmine and ginger species.
Returning residents and visitors to our islands frequently comment on how sweet our air smells compared to the mainland with the abundance of flowers in bloom now. 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. Our moist humid tropical climates have the potential for sulfuric 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 or olena as they traveled throughout the tropical Pacific. Cardamom and many others are spices but were originally used as medicines and have anti oxidant properties. The ginger used in Thai cooking is galanga 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.
Other relatives come from the new world and Africa. There are around 50 genera and over 1,300 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 or more feet 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. The 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 or Hedychium flavescens from India is another fragrant specie common in wet forests and along east Hawaii roadsides.
The shell ginger with its 3-8 foot stalks of evergreen foliage is frequently used 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 a mulch application 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. If you want to create a tropical look in places like Seattle, use guava jelly gingers and cannas along with the hardy windmill palm, trachycarpus fortune.
Take note that Kahili ginger or Hedychium gardnerianum tends to form seed that can be easily spread by birds. It is now found in many moist Hawaiian forests up to 6,000 feet elevation and is considered an invasive species. If you do decide to plant it, make sure the flowers are removed before they form seed. The rhizomes of Kahili ginger are tenacious so be prepared to use a pick or o’o to remove them.
Norman Bezona is professor emeritus, University of Hawaii College of Tropical Agriculture and Human Resources.
