It creeps along the ground, so its height is about 3" but the spread can be around 2'6" once a plant gets going.

..but you can cut it back in spring to re-sprout from the centre. It is very floppy and will flop onto nearby plants. We had one last year at Standen that was a metre across!

I've just poked one into my drystone wall to see if I can get it going there!