Any chance of a photo? And do you actually mean 'infertile', or is it a typo and you mean 'in fertile (soil)....'?

In Steve's first question, he says "in poor soil".
First, Steve, I would double check the sun exposure: just a few feet can make a big difference in the amount of sun the plants get, if there are structures, large shrubs, or even trees about. Checking where the sun goes several times a day can tell you a lot.
Second, look uphill from the plants. Is there a vegetable garden, well fed lawn, or even a farmers field that might be draining nitrogen into the area? Other plants on the same level that are well fed can do that, too, if they are within a meter or two.

I had the same problem last year when an eryngium planted the previous year still hadn't flowered. This year it's lovely. I also planted two more early this year and there is no sign of flowers on those either so I think they maybe need a year or so to settle in. That seems to be my experience anyway.