Posted: 21/06/2012 at 16:34
@Rob Stevens, its better to pack them in tight.
The Cosmos need pinching out regularly and I planted mine at 10 inchs apart but you could probably do even less since mine still flopped, especially in all this rain. They really need tall plant support or twiggy sticks.
The Cornflowers stood up unsupported and don't mind competing for space. I didn't thin mine out or even feed them and I still got hundreds of flowers.
The pic below shows Cosmos, cornflowers and Candula from late summer 2011. All plants were packed cheek by jowl.
and here you can see the roots of the cornflower clump, I just let them mat together, the Achillia in front helped a bit. But I don't over winter any of them, I just collect seed or let them self seed.