Anemones and ranunculus like a very long, cool establishment period to develop a robust root system and lots of foliage to support an explosion of blooms in the few months of cool spring weather around here. The plant also goes dormant in excessive heat. The bloom time for ranunculus seeds planted in the fall is around march, and when planted in the early spring, the bloom time is in. October 13, 2018 january 15, 2019 categories uncategorized annual, container gardening,. In zones 7 and warmer, there are two planting windows — late fall and again in late winter or early spring.