Sunflower seed heads for bird feed
I'm growing a small variety of sunfower (http://www.crocus.co.uk/plants/_/helianthus-debilis-vanilla-ice/classid.2000014780/). I wonderd if i should leave the flower heads on when they've gone over for the birds, although the centre seems slightly furry, not seedy like the traditional big yellow sunflowers. Do i just need to eave them longer or shall i dead head them? Not sure if all varieties of sunflower produce seed that can be left for teh birds to feed on.