my water lettuce and hyacinths are doing a really nice job keeping my pond crystal clear but there also kind of boring. i know the hyacinths bloom but they only last a day or two and then thats it unless some of the offshoots decide to bloom like just happened a few days ago anyways im thinking i need some lilies cuz they are so purty and they dont die in the winter should i wait till next spring to give them a shot or is fall a good time? also how many would you think i would need in a 11' round pond thanks for any help in advance