Ok, I was working in that part of the garden, and I forgot to mention I have a lot of Cannas there, right up against the watertank (which is a nice natural green colour. The cannas were no ID from a friend's garden, but I think they are Tropicana and Bengal Tiger cultivars. Firstly, I need to know if Cannas are compatible with Hostas. If they are, then I think that the bright stripey foliage of these (one with red and one with yellow) would be a nice backdrop for a solid blue Hosta. It should be quite large, but not as large as Cannas. If I only buy one or perhaps two at most then I can afford more remarkable varieties, and take time to look after them properly.
