Rachel, mine was given to me and I never changed the soil. But other plants this person has given me were in very ordinary (poor) soil. I put the whole pot down on the soil in my new pond. That soil was a mainly clay mix and organic matter (what I thought would suit swamp plants). The Lasia has sent its roots down through the pot as well as over the side and into the mud. I've just moved it into another pond that isn't subject to the same amount of flooding. But the roots looked like they were revelling in the mud.
I've heard that it's a plant that grows on the edge of water and floats out over it. So it might be more a matter of lots of water rather than type of soil.
