If you are in the UK, and you're growing this outside, its treated as an annual in this country, so whatever's happening to it doesn't really matter, since its going to be binned anyway. They do sometimes survive a winter, but get rather straggly and don't bloom so well in their second year. Or are you trying to grow it as a houseplant?

I had thought they had a textured leaf anyway. could you add a photo of the problem?

I am trying to grow it as a houseplant...