"Glossostigma elatinoides is much in demand in Japanese-inspired aquariums. It is one of the smallest aquarium plants, and thus a good foreground plant. A difficult plant demanding a lot of light. Grows upwards if light is poor. Make sure larger plants do not overshadow it. When planting in the aquarium small clumps (approx. 1/8 pot) should be placed at intervals of a few centimetres to help the plants grow together more quickly. CO2 addition and soft water promote growth significantly"
This is from Tropicas website, not much I can add, I think it needs a good plant substrate, it grew well and fast, got tall around the edges were it was shaded, but that looked quite nice too. It can get too crowded so I used to pull some of it out, as it overshadows itself, you can plant smaller clumps than Tropica says if you have the patience either way it will fill out fast if its happy.