Mostly depends on what happened the year before; too much shade, trimming the leaves prematurely - while they were still green, not enough nutrition, moisture, sun, etc. Sometimes it's squirrels, rabbits, etc. Ethylene gas would destroy the embryo, if they were stored near anything emitting ethylene gas - apples, bananas, etc.

it could also be that they are a later flowering variety. only time will tell. but give them a good foliar feed and they may flower for you next year.

With SBG re waiting a while longer yet. Assuming that you purchased them last summer/autumn and they don't flower then it would indicate that they have been badly treated at the point of sale.

I would have planted them 4"-6" deep, myself, though that would have affected next year's blooms, rather than this years. Who sold them to you, Ian? One of the growers, a garden center, or someone in the produce market?

Thanks to you all, sorry for delay.