They look like carrot plants. Are you sure you sewed the right ones?

Perhaps they are still very young plants & take longer than one year to bulk up. They certainly would not flower in the first year if they really are Oriental Poppies.

they don't look like oriental poppy to me either. do you have a picture of the original plant and or the seeds you had.

Thank you all. It's very puzzling. The seeds definitely came from a bright red oriental poppy. I collected them in a paper envelope and labelled them straight away. I'll leave the plants until next year and see what happens!

Welsh poppies (Meconopsis cambrica) maybe?