This Japanese selection of the moisture-loving Iris ensata was introduced prior to 1940, but is still very popular today. I. 'Umi Botaru' is topped in mid-June with 30" tall stalks ending in large purple flowers spattered with flecks of white. Iris ensatas are very durable in all but the driest soils, but really explode when grown in very moist soils or as a marginal aquatic. We recommend dividing Japanese iris every 3-4 years to maintain good flowering.