It's a Bog Plant not a Pond plant. You could site it at the edge of the pond,provided the edge is continually damp, like a bog. They don't grow in ponds.
It likes to be in full sun and poorly drained soil. It's a bog plant. You could rectify the situation by making it a sump to live in. Dig out the soil and line the base with a heavy duty plastic bag or piece of pond liner. Pierce it with a few holes to allow slow drainage and fill with fresh soil and fine bark mixture. Water this well before planting (It naturally grows in clay soils but I expect this is hard to come by.)This will help stop it from drying out.Keep it protected from strong wind and hot midday sun.