Robert wrote:
I suppose it depends on where you are. I sowed my first ones in November in
Plymouth and they are full of flower buds about to open when we get a warmer
spell

I'd say that and the situation of your plot. I simply cannot afford
planting early - my plot is by a disused railway line, in a deep kind
of valley and is full of furry and feathered creetures. I have in the
past lost lots of seeds to them. I find that if I wait and there's more
people on the allotment and warmer weather, not only my seeds germinate
quickly, they don't get eaten and the creetures get scared by the
people lingering on the allotment till well past dusk. I also start
lots at home before transplanting. I'm also hitching to get planting by
end of Feb as I did when I lived in France, I have learnt to be patient
now that I live in Manchester ;o)