I grew H. 'lollipop' a few years ago. I started them off on JI no 1 and used soil based compost through out. They did really well and survived in the garden for about 4 years until one wet spring when the slugs got them.

Grew a lot of them at the previous house. Mixed colours, but the soil there was wrong for Heleniums and we lost most of them. Our fault not the plants.

Thanks for the info. I think it might be the compost.