Dehydrated kāhili ginger flowers.
Although the Ginger (Zingiberaceae) Family is generally safe, info is sparse on kāhili (Hedychium gardnerianum) as an edible. Although not expressed directly in any literature, I determined through inference and experimental practice, that yes kāhili ginger flowers, flower buds, rhizomes, and new shoots are edible in small amounts.
We know that H. gardnerianum is considered to be a folk medicine of the people of Sikkim state in the Indian Himalayas . There is evidence that H. gardnerianum was used as a ginger substitute in New Zealand during World War II food rationing .We also know that H. gardnerianum does not seem to have any strong toxicities in humans, dogs, cats, or horses  and that it is highly palatable to livestock  and used in ruminant feeding in some areas . All of the evidence seems to indicate that uses of H. gardnerianum for both aroma and as a flavor/spice for ingestion are safe. It is always wise to start with a small amount when trying a food for the first time.
Yellow butterfly ginger (Hedychium flavescens) on the lower left, and white butterfly ginger (Hedychium coronarium) on top. We know that the chemistry of the three closely related species – H. coronarium, H. flavescens, and H. gardnerianum – does not significantly vary and that they share most of the same dominant aromatic compounds.
White butterfly ginger (H. coronarium) is edible: its rhizomes are known to be eaten in India [5,6], and although it is described as a famine food, this assessment need not apply if new or creative edible uses of the plant can be found. Its flowers and flower buds are edible and can be used like a vegetable as well.
Pulling kāhili ginger flowers off of the flower head is usually done while watching a movie and talking story with friends and family.
Butterfly ginger flower wild yeast starters. Kāhili (H. gardnerianum), white (H. coronarium), and yellow (H. flavescens) are often described interchangeably in literature on the essential oils, so we can assume that many of the same medicinal qualities also are present in kāhili (H. gardnerianum).
Look for the orange butterfly ginger pin in the Savage Kitchen app & online foraging courses, coming in 2020. A “butterfly ginger” pin can be dropped anywhere you find kāhili (H. gardnerianum), white butterfly ginger (H. coronarium), or yellow butterfly ginger (H. flavescens).
 ENVIS (Environmental Information System Center: Sikkim).[nd]. Medicinal and Aromatic plants in Sikkim. Gangtok (India): Forest, Environment & Wildlife Management Department, Government of Sikkim. http://sikenvis.nic.in/WriteReadData/UserFiles/file/Medicinal%20&%20Aromatic%20plants%20of%20Sikkim%20from%20FRLHT.pdf
 NRC (Northland Regional Council). [nd]. Wild ginger, Pest Facts No. 4, Whangārei (New Zealand): Northland Regional Council. http://www.rnzih.org.nz/pages/pest%20facts%204%20-%20wild%20ginger.pdf
 ASPCA (American Society for the Prevention of Cruelty to Animals). 2017. Toxic and Nontoxic Plants: Kahali Ginger. New York (NY): ASPCA. https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/kahali-ginger
 Carvalho MJ, Carvalho LM, Ferreira AM, Silva AMS. 2010. A new xanthone from Hedychium gardnerianum. Natural Product Research 17(6):445-449. https://www.tandfonline.com/doi/abs/10.1080/1478641031000118906?journalCode=gnpl20
 Lim TK. 2017. Edible Medicinal and Non-Medicinal Plants: Volume 12: Modified Stems, Roots, Bulbs. https://link.springer.com/book/10.1007/978-3-319-26065-5
 Kunkel G. 1984. Plants for Human Consumption: An Annotated Checklist of the Edible Phanerogams and Ferns. Oberreifenberg (Germany): Koeltz Scientific Books. https://books.google.com/books/about/Plants_for_Human_Consumption.html?id=7L0H0WBBMOkC