My lovely sunflower plants opened their flowers today - not a hint of sun, but they unfolded and searched upwards anyway.
These are the lovely dark coloured ones, Black Magic F1 - suppose there is the answer, they are magic! It says on the packet that I will have flowers until October. I planted them in the corner of my vegetable bed, as they are described as being good for wildlife - attracting butterflies and insects - and also so that I can collect the seeds to feed to the birds later in the year. However they are a perfect colour match for my beetroot, which is proving a great success!