When can you transplant a flowering poppy?

Poppies are notorious for being impossible to transplant.

However, if you've planted starts in peat moss, you may have more luck planting them than digging flowering poppies out of the ground and transplanting them to a new location.

If you want to re-arrange your poppies, you could seed the area where you want the poppies to bloom and simply dig up the old stand.