First is May 15 to 31 depending on how much a risk take you are and I would say end of Sept first part of Oct for last. Or vice versa. I had blue poppies for several years but the clumps rot from the middle and then they are unsightly. So after the newness wore off I let them go. I did plant some yellow meconopsis and they self seeded cute little yellow poppies in a shady area with foam flowers and such. I am okay with them. Kind like a ground cover.
