Most of it is just pushed into the gravel or into holes in the wood or between large rocks. It doesn't really seem to care. It does not root and I've only been succesfull getting it to attach to wood. It grows the same where ever it is. I found that its best to start with small peices, the one in the pic above is about 2" across. It should eventually look like a little bush. If its not growing I would suspect not enough ferts in the water.