Here's a great article from Tropica about this plant written by our friend and brilliant aquascaper George Farmer: https://tropica.com/en/articles/lobelia-cardinalis-mini/

Lobelia cardinalis grows wild in Northern America. In the nursery this plant is cultivated in marshy conditions, forming dark-green leaves which are purple underneath. In aquariums the leaves turn a beautiful shade of light-green, with stems 10-30 cm tall and 5-10 cm wide.Pots are brimming with plants and have lots of mass and healthy, 

well-developed roots.
Most pots can be divided into several portions or individual plants which are planted separately.