Trialsguy,
I don't know about the cabbage but I have a friend that gives me several hundred extra water hyacinths every year. I put them in an area around trees to keep them floating(they MUST float). and we get far too cold in the winter for them to survive and if they do get too thick they are easily removed. They are beautiful when flowering and are a great filter and fish habitat.



I put these in on 7/7 and they are spreading slowly and look much nicer now. If you're interested I will post another pic from this weekends trip.