Thanks Adele for your informative answer. I would imagine that early August would be better than late (last week, into September). based on my experience in the US, (cascades, rockies). If not late August our other option is to go in earlier, July, or even late June. It's just that the airfares are so much cheaper in late August.
When do you make reservations for the huts? Is it done way in advance? I love wildflowers, but competing for hut space might lead to a decision that is based more on how the quality of the trip changes due to peak visitor times.