The grass Puccinellia maritima is an important saltmarsh ecosystem engineer exhibiting wide morphological variation, which is partially genetically determined. Nevertheless, nothing is known about its population genetics or how neutral genetic variation is distributed throughout its geographical range. Here, we describe 12 polymorphic microsatellites pooled into two multiplexes for this octoploid species. Assessment of 24 samples from three populations revealed 4 to 29 alleles per locus, with variation in allele presence and abundance between populations. The transferability of these markers is reported based on their cross-amplification in six other Puccinellia species of different ploidy levels.