Iris ensata Montrosa - Japanese Water Iris

They thrive in a damp and marshy soil, without limestone. They also tolerate a fresh soil, even if not waterlogged, as long as it doesn't dry out in summer. On the other hand, they prefer a rather dry soil in winter. We have planted them near an artificial stream, which maintains a high water level during the warm season. In winter, we let the water level drop by about 15cm (6in), so that the stumps are above the water, just like in nature where river levels decrease in winter and rise again in spring with the melting of snow. Their cold resistance is excellent up to about -18° (-0.4°F). It is further enhanced if the soil is dry.