The ones I planted last year took a long time to show. The were planted with summer-flowering irises and the irises were over before the Crocosmia leaves were more than a couple of cm high. They didn't produce any flowers. The leaves have stayed evergreen all winter, I'm hopeful that the plants will flower this year.

thanks for that... so i may be waiting some time, maybe next year before they start to show..

Agree with Landgirl's answer. I have to add though, your window boxes may not be deep enough to grow Crocosmia well - they like a container that's 12 inches deep. If you have one of the smaller varieties, they may be alright.