SEA OF BLUE: Rangitikei Iris Society past president Gordon Koberstein in a bed of irises he has bred, which are as yet unnamed. 'You need to grow them on for at least three years, so you know know they'll perform'.

Name:     Gordon Koberstein	Recreation/Sport: Flowers
Relationship:	Country:     New Zealand
The Rangitikei Iris Society's show will be a burst of colour, writes LEE MATTHEWS. Low-flying clouds of colour crowd the iris beds at Gordon Koberstein's Palmerston North garden, Helmpark. He is gearing up for the Rangitikei Iris Society show, which opens tomorrow, walking the gardens, eyeballing his 500-plus iris plants to see which will have blooming stems ready to stage. As he walks, he talks, explaining irises, and his hands are busy, dead-heading spent blooms and gently feeling for emerging bud shoots. "They're easy plants," he says. "Put them in the right conditions, and they'll flower their hearts out for you." Different types of iris bloom nearly all year round, in conditions that range from bog to desert. November in temperate Manawatu is the moment for bearded irises to take centre stage, standing proud in full sun. Iris means rainbow, and the flower's colours fill almost all the spectrum. The only colour that is proving elusive so far in bearded irises is a true red. Hybridisers are working towards it, crossbreeding from the brown and crimson and deep purple colours. Mr Koberstein is confident it will happen one day. "They got the black tulip, after all." He has grown irises all his life, learning the art from his mother and aunts. There was a strong local connection as well. About 50 years ago, Bulls-based iris breeder Jean Stevens was hard at work, hybridising irises. Many of her best are still grown, and are known for soft, melding colours and simple, classical form. Bearded irises grow from a rhizome, a pale brown finger of stem that sits in full sun, on top of the soil, and puts out roots. Leaves form in pairs, and the flower stem erupts from the front or new growth end of the rhizome. Each year, the rhizome forms another pair. Mr Koberstein says it's best to lift and split the rhizomes after three years, to avoid overcrowding and to refresh the soil. "You just cut away the old part of the rhizome that's spent, and plant the newest part. It starts all over again. The best time to do that is after it has flowered in the spring." Bearded irises enjoy rich soil full of nutrients. Mr Koberstein fertilises with a mix of blood and bone, a touch of superphosphate, some sulphate of ammonia and a good handful of potash. The potash supports strong cell structure and better flower colours. Bearded iris husbandry is straightforward. The old, browning leaves need to be stripped off the rhizome, and don't cover the rhizomes with soil or compost. They need sun. About the only disease the plants get is rust, but it pays to keep an eye out for voracious little green aphids. Adventurous gardeners who want something new can try to hybridise irises for themselves. It takes patience and a pair of tweezers, to spread pollen from one flower to another. If you have effectively mimicked a bee, a seed pod with up to 30 big, round seeds will set. Once the pod has dried off, the seeds can be planted in a pot. It usually takes two years for the new iris to flower. Mr Koberstein said the Rangitikei Iris Society was keen to welcome new members, and anyone interested in the flowers could come to the show. Anyone who wanted to show flowers should pick them with long stems, as close to the rhizome as possible, and bring the stems to the Palmerston North Community Leisure Centre between 8am and 10am tomorrow. "We'll show you how to set them up for the show bench." He warns would-be exhibitors to not lay the flowers flat to transport them. Iris petals are extremely delicate and bruise easily. Mr Koberstein transports his show stems using recycled newspaper. He folds a broadsheet section in half, then rolls it round the pipes of a vacuum cleaner, slides the newsprint tube off and secures it with sticky tape. Set on end in a bucket of water, the wet newsprint rolls each take an iris stem, and hold the flowers safely upright and away from each other. Rangitikei Iris Flower Show, Palmerston North Community Leisure Centre, 569 Ferguson St. Saturday, 1pm to 4pm, and Sunday, 10am to 4pm.