How to Harvest Seeds from Cut Sunflowers String of Pearls Plant 'Care and Growers Guide' Everything You Need to Know Planet Desert Plant your poppies when it's cold! Poppy seeds require a period of cold to germinate and grow, so they generally do best when planted in the late fall or early spring. Plant Parents Rejoice: IKEA's DAKSJUS Collection! Brit + Co Green Flower Seeds at Lowes.com