I don't really know the answer but the experts will tell you. Anyway I have cut mine down as usual because the foliage has splayed out all around, taking up a lot of space. I did the same thing last year and it came back and made a lovely show this year.

Penny is right. They sprawl about. so chop em back, a bit of feed and water and the leaves come up nice and tidy. Having said that they hate my garden and I am jealous of anyone who grows whopping great poppies year after year.

Cut off the seed heads unless you want to ripen them and if the foliage is really untidy then you can cut it back and the plant should produce new growth. They are pretty tough plants and fairly resiliant.

I cut all mine down today

I cut mine back last year and planted nicotiana plants inthe gaps left. They came back healthy and happy this year. I've still got a few flowers.

I cut my foliage back every year, it comes back fairly quickly. Mines have yet to flower but I have plenty of big juicy buds just waiting!