Posted: 07/06/2014 at 16:01
For oriental poppies, I wait until they have all finished in a particular patch then cut the whole plant including leaves and stems down to the ground. New leaves soon appear which overwinter. I don't think oriental poppies will send up more flowering stems in the same season, even if you cut the flowered ones out immediately.
With opium poppies I snip the heads off and they usually keep forming new buds from the lower leaf joints for a few weeks but eventually they become rather tatty and either die off of I pull them up.