Gorgeous, isn’t it? Such a pity something so nice is actually a pest. Kahili ginger (Hedychium gardnerianum) is in full bloom now, rioting all over Volcano Village, including my yard. Its heavy perfume is an evening serenade, a fragrant backdrop for romantic stargazing on clear summer nights. Oddly enough, my cat might be allergic to it – he’s developed a rapid, machinegun-like kitty sneeze. Personally, I think the scent has a nicotine-like undertone and is inferior to white and yellow ginger. That, and K-ginger's invasiveness, permits me to charge full force with my machete. Snicker-snack!
The first Hawaiians brought "shampoo" ginger, which they called awapuhi (Zingiber zerumbet), to these islands. However, so-called “Kahili” ginger, like other gingers that have naturalized here, was brought to Hawai'i as an ornamental in the early 1900s, and since then it has created enormous environmental problems in the native rainforest, crowding out other plants. Heard of the invasive Himalayan raspberry? This is Himalayan ginger – no kidding. “Kahili” is a misnomer; it’s not Hawaiian at all. Sad to say, it’s just someone’s clever way of marketing a nursery product by co-opting a Hawaiian identity. Again.
Himalayan ginger is well-adapted to rainforest environments. It is shade-tolerant, is tall and has broad leaves to block sunlight from reaching competing plants, and it spreads by rhizomes and seeds, which makes it even more successful. Birds are attracted to the bright red seeds and spread them around to other areas.
Sure, you can keep hacking it back, but it’ll only laugh at you. At the nature trail of the Volcano Art Center’s Niaulani campus, volunteers spend every third Sunday of the month digging out the rhizomes in order to preserve the rare native species of the old-growth forest there. A good ecotourist activity if you’re interested, by the way. Click here for more info.
Hawaii Volcanoes National Park uses another method: They cut the plants down to the rhizomes, and then they spray an effective (but expensive) chemical pesticide until the point of runoff. (I won’t say which pesticide it is – sorry. But you can ask them yourself, if you’re really desperate and have a big problem.)