If anyone wants to try Dardanus, I finally got some answers! After persisstent emails this is what I recieved from John Scheepers bulbs:
My Dutch colleague has also spoken with the grower of I. Dardanus. He confirms that each rhizome should be planted more or less horizontally with the buds sideways and the root end tilted down and prior year growth tilted up. He said that if it is planted simply horizontally, it will right itself.
The cut end is from prior season division. The withered end is from the prior year's stalk. It will grow toward the warmth of the soil and right itself as it matures.
And this is what I recieved from Odyssey Bulbs:
Plant the rhizomes horizontally with their tops exposed, in a sunny location. Fertile, neutral to slightly alkaline soil. If you garden where there's summer precipitation and humidity they'll need porous soil and may require some protection from rain. Regards, Russell