In our zone 5 (zone 4 in the USA) the simple "Corydalis Lutea" began to flower in May and today 6 months later it is still looking cheery...continuous bloom for more than half a year. And it has held its own even after a few frosts that have occurred over the past couple of weeks.
I also am impressed with another classic "Rudbeckia Triloba". This particular stand was eaten back earlier in the summer by deer and now I am glad this happened as flowering was delayed and even now it is looking wonderful.
