Zostera marina is a PERENNIAL growing to 1 m (3ft 3in). It is in flower from June to September, and the seeds ripen from August to October. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Water.Suitable for: light (sandy) and medium (loamy) soils. Suitable pH: acid, neutral and basic (alkaline) soils and can grow in saline soils.It cannot grow in the shade. It can grow in water.