Skill Level: Intermediate
Diplarrhena moraea—the Tasmanian Flag Iris—is a graceful, evergreen perennial native to the cool, moist regions of Tasmania and southeastern Australia. In the garden it forms neat fans of narrow, sword like leaves, typically 18–30 in. tall, giving it a clean, architectural presence. In late spring to early summer, it lifts elegant white flowers marked with soft violet or blue above the foliage.
It grows in full sun to bright, filtered light, preferring moist, humus rich, well drained soil. In the wild it inhabits open heathlands and moist montane slopes, where soils stay evenly damp but never waterlogged. Consistent moisture during the growing season is appreciated. Good drainage is demanded. Hardy in USDA Zones 7–9, it benefits from shelter from harsh winter winds in colder gardens.
Our Seed Germination Experience
Although often described as having mild morphophysiological dormancy, we’ve found D. moraea to be more challenging than expected. It took three attempts before we achieved germination.
We sowed in early winter in an unheated greenhouse, allowing the seeds to experience natural temperature fluctuations throughout the season. Germination finally occurred 6 months later in June last year, with a modest 25% success rate. Seed provenance is unknown. Once up, the seedlings grew slowly but are now large enough to plant out once the weather warms.
Photo of Mature Plant: Australian National Botanic Gardens
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