If the growth buds don't freeze solid, some will survive. We cover the
hyacinth pond with plastic and the surface does not ice over. We strip the
dead leaves in the spring and toss the mushy, dead hyacinths. About half
generally survive here in Jackson, MS. Those that are frozen solid die.

Jim

"Michael Shaffer" wrote in message
news:bxPgf.14619$om5.9108@dukeread04...
The first frost killed all my water hyacinth, should I leave them or
could the rotting be bad for my Koi?