It is a member of the wider daisy family but it looks like the annual fluffy blue ageratum on a massive overdose of steroids. In fact it is a perennial woody shrub from Mexico which reaches about 3 metres high and nearly as wide with big leaves (slightly felted) and big fluffy, fragrant flowers in lilac blue. Normally it is in full flower for our spring garden festival but it is a little late this year. It is not very hardy and presumably it didn’t like the cold winter.
We grow it outdoors here but we saw it in the covered house at Kew Gardens in London under a different name and then we saw it in a garden in Italy under yet another variation but it appears that all are more or less correct: Eupatorium sordidum, Eupatorium megalophyllum, Bartlettina sordida or Bartlettina megalophylla. It does not appear to have a common name so it is referred to here upon occasion as that giant overgrown blue ageratum-like plant. You are not likely to find it for sale but it does grow easily from cuttings if you find somebody with a plant.