When is it time to throw away water lettuce and hyacinth? I mean, how do you know when it is time? What do you look for? The leaves on the hyacinth are slowly turning brown but there is still some green leaves. The water lettuce is laying on it's side and the roots are floating almost on top of the surface.

Where do you live? The first real frost will cause the water lettuce to turn white and fall apart soon thereafter. Water hyacinth just tends to turn mushy. If you have few of these plants, you can wait until the first hard frost to then throw them out. If your entire pond is covered like mine with water lettuce, I've been tossing it for over a month now. Last Sunday, I removed half of what was in the pond. It was still nearly 100% covered even with removing it weekly since it was still green and growing. I try to get most of it out before the first frost. Normally, we would have had that weeks ago but this year, we only had a minor first frost a few days ago. My water lettuce is weakening but still alive. I will try to get more each week until I've got it all before the pond freezes. With the warmth we've been seeing, that may not even happen this year (or next year)!

I live in Oregon not to from Mt Hood.
We have been having heavy frost and temp's below freezing. Highs in the 40 to 50's. My lettuce leaves have been getting yellowish white (they have been kinda yellow all year) and mushy for a while now. With the roots floating I thought maybe it's getting close to trash time ;) I have only thrown out a few this year. They didn't multiply well in my pond.

I'd start removing it tlc. As it turns yellow I remove. I try not to let it turn white, that be bad.

If you feel you need coverage there's lots of fake floaters you can buy, like lily pads, etc. I've used them. I've even floated fake ivy. Normally it doesn't float, but I found spreading black waterfall foam (liquid that dries into foam) on the stems it does.

I've started plucking mine out too. My hyacinths are actually lasting longer than normal because they're under the net.

Sadie, My hyacinths are still doing well too! Surprisingly.

Lettuce, forget it, it's done. We were down to 25 last night, today lettuce is white on the edges, tonight it's coming out.

My lettuce had yellow outside leaves all summer but are now more so. I threw a bunch out last weekend. I still have some left but boy, oh boy could I see the bottom of the pond! Some of the lettuce roots were well over a foot long and I had been trimming them all summer! Amazing they are!