We can't grow them anymore--they're on the noxious weed list, now--but when I could, they always bloomed during the monsoon season when the water temps went up.

Its our seasons here Tug ..as you have no severe winters and frosts they spread to cause problems for you.They are finished by our winters really a pond annual here seem to need longer periods of sun to flower than our summers can provide.

tug i read about them being stopped in warmer climats, and can see why as ray said, i guess i wont be having flowers ray then ;o( no hot sun here just warm, but the fish like them so dont mind, they eat the roots apparently, thanx for info tug and ray ;o))

I used to buy them every year and keep some in a tiny pond in a frost free conservatory over winter. They grew well there and multiplied. Every summer I put some in the outdoors pond where they survived but didn't grow. Water must be too cool, or too much competition from other weeds.
The coypu seem to love them as they always disappeared overnight from the large pond down by the river.
Perhaps Tugbrethil you could have some of our coypu and then you can grow water hyacinths again, except coypu are an even worse pest!

bertie im happy to have them in my pond but flowers would have been nice, never mind the fish like them and makes the pond looked settled in nicely ;o)) i might over winter one to have them next year,

I've had these for the last couple of years and put them in the compost possibly Nov or first frosts.I wouldn't want them in the house for 5 or 6 months but may be ok in a greenhouse if frost free.
Never any flowers but they provide a bit of cover for the fish.

thanx aster for your comments, i will have them again for my fish ;o)

Bonkersbon:
I never said that I didn't agree with the ban! I shudder to think what could happen if they got into our irrigation canals!

Bertie:
Coypu, too!

i know what you ment Tugbrethil and so did the guys, they were just saying how it all is here and how the weather reacts different to them, they dont live in winter here so dont spread like other countries, so i personally think where you are and other warm climates they should be banned so to protect water ways, you didnt say anything wrong ;o)))