(from a talk given at the Subtropicals Conference 2005) - published Summer edition 2005

The Genus Hedychium originates in South and East Asia - from India, Nepal, Burma and Thailand through Indochina to Southern China…and they are a promiscuous lot. They seem to hybridise freely even in their native habitats, making precise identification difficult sometimes. Flowers, often richly perfumed, are produced in terminal spikes above the foliage making many of them very attractive garden specimens. They epitomise all the alluring qualities we associate with tropical flowers; exotically perfumed, extravagant, colourful orchid-like blooms above lushly layered large leaves.

Commonly known as ‘Ginger Lilies’ or ‘Butterfly Gingers’, many of them tend also to be fairly aggressive growers, carpeting the soil with impenetrable layers of fat, succulent rhizomes. Foremost among these is the dreaded but beautiful Kahili ginger, Hedychium gardnerianum from Northern India. One of New Zealand’s most infamous pest plants, this species produces fleshy seeds which are eaten by birds and then dropped in the bush, where the rhizomes can eventually overwhelm all other plants, preventing germination of native trees. Unchecked, it could ultimately wipe out large areas of our northern forests. The fleshy edible seeds are the problem. In New Zealand conditions, many of the other hedychium species seem not to produce seed at all.

While Hedychium flavescens is also classed as a noxious weed here, it does not produce seeds, so its spread is much more controllable. It is really only spread by people dumping it in inappropriate places. Its aggressive growth rate however, makes it an overwhelming plant wherever its rhizomes fall. Speaking of the growth rate of this hedychium and most of the others, I would equate it to that of a vigorous canna.

All hedychium species grow well in shade or sun although flowering is most profuse in a high light situation. Foliage looks its best with dappled light rather than full sun. Soil ideally should be moist throughout the year but not waterlogged.

Hedychiums are frost-tender, but in frosty areas they can be cut back to ground level in autumn and thickly mulched for the winter. They are grown in this way in the southern United Kingdom very successfully.

The most famous of the garden-friendly hedychium whanau is H. coronarium, the ‘White Butterfly Ginger’ or ‘Garland Flower’, which grows to just over a metre high. Its spicy strong perfume is reminiscent of citrus blossom and the large-petalled, white blooms touched with lemon-yellow, make it a popular garden plant. While it does not appear to produce seed at all here, its aggressive growth, like that of H. flavescens can result in very large clumps in a few years. This is easily fixed with a sharp spade or a dose of strong glyphosate herbicide. Flowering begins in mid-summer and continues till about April or May. Foliage is light lettuce-green and rather soft but creates a lush tropical look very quickly.

Hedychium chrysoleucum is not listed by MAF as being in New Zealand. Nevertheless, a variety of this species has been sold for many years as ‘Candycane Ginger’. It is similar in many ways to H. coronarium, but the large bicolour flowers are apricot and yellow. Leaves are slightly narrower and stems are taller than H. coronarium.

Hedychium coccineum is an interesting member of the family. It is highly variable and vigorous and seems to hybridise with other species easily. Many of these hybrids, as well as the species, do produce fleshy seeds which is a concern.

Some clones of H. coccineum produce 12cm to 20cm cylindrical flower heads, packed with small tubular flowers in shades of reddish-orange to apricot with long stamens, while the hybrids tend to have larger flowers in many shades from yellow to deep orange and even pink although I have not seen any of the hybrids available in New Zealand.

Most varieties are about two metres tall, although some grow to around three metres. The flowering of the species seems a very brief affair which is a disappointment when compared to the long season of H. coronarium and others.

The popular Hedychium greenei, from Bhutan in the Himalayas, has handsome dark green leaves with maroon red undersides, while in autumn the large flowers are a very bright orange. This species is seedless but produces one or two viviparous plantlets from each spent inflorescence. These grow where they fall and are easy to control. It reaches about 1.2m and is a spectacular sight in bloom.

Hedychium thyrsiforme is characterised by a small head of pure white filamentous flowers in late summer and handsome foliage with light green, corrugated, hairy leaves. It makes a beautiful garden specimen even without flowers and appears to be seedless in our climate. The beautiful leaves of Hedychium thyrsiforme are shown to advantage here, together with the delicate looking white flowerhead.

Hedychium gracile also has white filamentous petals but the prominent pistils are a striking salmon pink. It is apparently fairly hardy and available in New Zealand, but I have yet to find it.

Hedychium horsfieldii, the "Java Ginger" is normally an epiphyte.

It grows only to about 50cm high and has thick rubbery roots with sticky hairs which wrap around branches and store moisture. The foliage is leathery, shiny and light green. Small, tubular yellow and white flowers appear from January to March and are followed by spectacular orange pods which open to reveal scarlet seeds. Its origin in the Indonesian tropics belies its hardiness in this climate. It makes a handsome tub specimen in dappled light outdoors and thrives among rocks or on a tree trunk in semi-shade.

All the hedychium species mentioned here grow easily and vigorously in the relatively frost-free areas of New Zealand. All need annual grooming, removal of old stems after flowering to maintain their lush glamour. All of them thrive best in slightly shaded, sheltered conditions with a consistent soil moisture level. Where seeds are produced, some vigilance is advisable as to their weediness potential.