Eryngium / sea thistle
Why hasn’t my plant flowered? It’s also still quite small. It flowered last year but so far this is it. Does it need a special feed ?
edited July 2019
Generally Eryngiums don't need much feed, they're often happiest in dry rather poor soil. I think it would probably be happier in the ground. The old multipurpose compost it's sitting in probably isn't ideal.
It’s actually been repotted in new multipurpose compost but I take your point and will change it over to the mix you recommend
They prefer low nutrient soil. Well drained and sandy / gritty if possible.
Much too small and early for them to have flowered yet. Give it another month or more and it should be fine. They self seed like crazy, so you will end up with many more.