5000 cleome seeds - mixed white, pink, purple - spider plantss - nectar flower for monarch butterflies marde ross & company cold stratification: the process of subjecting seeds to both cold and moist conditions. seed of many trees, shrubs and perennials, and flower seeds require these conditions before germination will ensue. soak the seeds in cold water for 6–12 hours immediately before placing them in a sealed plastic bag with moistened vermiculite ,or sand, or even a moistened paper towel for 2 weeks. plant 1/4" deep.