I'd be wary of cutting them down in hopes of delaying/extending bloom. I watched the YouTube vid and I am not sure I trust the information....mostly because Papaver orientalis (the perennial poppy) is absolutely NOT the opium poppy (P. sominferous...not sure of spelling; this is an annual poppy). If the presenter is not sure of that fact, I don't think I'd trust her information. I'm always leery of those who don't get important facts right.
