You don't mention what kind of poppies (oriental, bread seed, California, etc…), but it might not matter too much anyway. Where I am California and oriental poppies both tend to germinate in spring, which means they seem to be cool season plants. The orientals green up before the trees leaf out, grow quickly, and then flower and turn brown as soon as things heat up. California poppies are self-seeding annuals here, and continue blooming into the summer with continuous moisture. I'm in zone 6, Northern NM.

They should germinate if you keep the planters moist. Calif poppies are blooming now. You can also distribute seeds in the fall and given the right conditions, they will germinate on their own in spring.

My California poppies are done. They came up in Feb and pretty much finished 2 weeks ago. Camp Verde AZ

Quite a few different types of poppies. Prickly poppies (wild high desert),Oriental (many varieties),Turkish,German,Californian, and more,they all pretty much are surface sown and need direct sunlight on seeds to germinate,seeds need to be kept moist but not wet. Seeds can be washed away easily if planted outside so starting them in peat pots works well and reduces seedling shock when transplanted. Peat pots can go directly into ground instead of actually transplanting seedlings. Poppies need a lot of sunlight.Best to know exactly what kind you are trying to grow then look up on line (Google) to read about what is best for the type your are trying to grow.Many flower seeds need to go thru a stratification process, sowing/planting them one season but they won't actually grow until the following season.They need to go thru cold weather,need to be soaked, or other stratification processes.Example.... Since I am in Arizona when I grow sweet peas I put them in ice cube tray fill with water freeze then just plant ice cubes makes them start really fast. Poppies are one of my favorite flowers.