Lobelia cardinalis planted aquarium In aquariums the leaves turn a beautiful shade of light-green. It needs intensive light to thrive. Widely used in Dutch aquariums in so-called ''plant streets''. In open aquariums it grows above the water surface, where it forms very beautiful scarlet flowers and the leaves regain their color. Lobelia cardinalis Common Name: Red Lobelia Lobelia cardinalis 'Small Form' Description pH range: 6.2-7 Temperature range: 20-26 C Water hardness: Soft- Read more