I've never heard that about the ph. I don't have any luck with hyacinth in my pond, but I've always thought the fact that they failed was simply because of the fish nibbling at the roots. However, I have grown hyacinth in my stream where there are no koi to nibble the roots, and it doesn't do well there either, so maybe there is something to that. However, I've had great luck with hyacinth in separate containers, like large flower pots with no holes. They bloom like crazy in those.

I have a ph around the same as yours and I have more hyacinth than I know what to do with even with a pond full of koi nibbling roots. I actually need to net it and throw it out 1x a week this summer it grew so fast. It did do an awesome job of keeping sunlight off the bottom of most of the pond and my water was crystal clear all summer.

Good luck next summer

Interesting is that Hyacinth have a nice purple flower and I only had one flower all summer and I thought that was b/c my pH was too high!

Maybe someone knows better. At least you know it wasnt the pH that stopped your Hyacinth from flourishing.

Well it may not be the ph but I still don't have much luck with this plant. For the last three years our spring has been cold and raining for most of late May & June (spring here). This year my martagen lilies didn't bloom till the end of June and they are usually blooming by the first of the month. Funny thing though I have a silver lace vine that is not supposed to be hardy for here--a Zone 6 plant that survived the winter and grew like crazy. I usually replant this every year as even in my short season it grows 10 ft long or more. Like it as it doesn't get aphids. If it survives this winter the roots will be huge! As for hyacinth I guess I'll use parrot feather instead as it loves my pond.

Last year I had a very poor crop of hyacinth but this year I had another bumper crop of them. Other plants were quite successful. I quit taking chemical tests a few years ago and I don't add chemicals other than koi clay or dechlorinator. The hyacinth will soon die off and then the ritual of dumping the ugly blck plants begins.

Check the dissolved Iron in your water. Thats what was holding mine back. Any aquarium store should have a test kit.

I have friends in areas of the country with very high ph and they are also the areas where they are illegal because of the terrible clogging of waterways. I don't think high ph is a barrier to their growth. They are tropical plants though and need sun and warm water.