Yes, you should thin them out. They will take over if you don't keep them thinned. You can probably sell the extras on ebay or craigs list if you want. I bought 20 Hyacinths on ebay at the start of the season and now they are starting to crowd out my lilies as well.

Yes, you should definitely start thinning out your floating plants because chances are that the water hyacinth and water lettuce are blocking sunlight from reaching the crown (growth tip) of the waterlily. Sunlight hitting the crown is essential for the lily's survival because this is where the leaves, flowers and new roots develop. Good luck!

Cat

I've already thinned mine at least three times this season. I started with four.

I know....... water hyacinths NEVER stop growing. I take out excess hyacinths and munch them up into compost for my terrestrial plants. Water hyacinths have a lot of nutrients in their bulby leaves.

Cat

Oh boy! I'd better get crackin. Hope I didn't lose the season.