Eryngium

I love them!!

They come in lots of different heights and some are very showy (I have one with stems that stay blue well into winter) whilst others like the second of GD's photos are more 'gentle' though they still prickle.

This one is growing in one of my neighbour's gardens. It always makes a nice clump, and looks very good. It hasn't really come into its full glory yet!

Sea Holly. Lots of different sorts. Colours ranging from grey- blue to near purple. A nice big clump looks lovely .I have some with deep purple stems. The wild ones on the sea shore near us are a very pale blue.

Eryngium Alpinum is your best bet. A real stunner.

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I have some just taking on their blue colouring now, but mine are very leggy and you can get more compact varieties. I love them and so do bees, but they are terrible spreaders so you'll have to keep an eye on them. Not good at photos I'm afraid.