We have very little information on this species and do not know if it will be hardy in Britain. It will require wet conditions or shallow water. There must be some doubt over the validity of this name. The species is said to have a synonym of Panicularia fluitans, this name is also given as a synonym of G. fluitans and it is possible that G. borealis is no more than a synonym of G. fluitans.

Seed - cooked. Ground into a flour and used as a cereal. The seed is very small and fiddly to harvest.

Seed - sow spring in a greenhouse in a pot standing in 3 - 5cm of water. Surface sow the seed, or only just cover it. Germination should take place within 3 weeks. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in early summer. Division in spring. Very easy, larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the spring.

Wet places or shallow water.