Conversing with Joanie McLean of Mellow Marsh Farm in North Carolina unearthed the following…
Spartina Alterniflora is hard to grow from seed, and particularly hard to winter over. Seeds need to be watered and drained frequently to simulate the tide. When watered, they must be fully saturated with water and then drained completely.
When growing, it’s ok to use fresh water and regular soil. It’s only at the time when the plant needs to get ready to be placed on the shoreline/in water that brackish water is introduced. Then, so as not to shock the plant, start adding salt water bit by bit to the draining ritual.
If we ever need Spartina Patens (high marsh grass), they have thousands of plugs ($.35 per plug) and lots of seed. This is not the variety that would grow in/on the water, though it is salt tolerant and normally can sustain salt water inundation 3-4 times per year (rather than daily as is the case with Spartina Alterniflora). If we ever want to play with S. Patens we should let her know and she can hook us up.