- Zone: 4-9. - Bloom- Summer-Fall. - Light: Sun- Part Shade. - Heat Tolerant. - Who doesn?t love the no-drama hydrangea in the corner of the garden that quietly produces waves of big blossoms in summer? These easy-care plants are perfect for garden beginners and experts alike. If you are looking for a new garden challenge, try growing hydrangeas from seed. Read on for information on planting hydrangea seeds and tips on how to grow hydrangea from seed. - It?s pretty easy to clone a hydrangea cultivar by rooting a cutting from that plant. But you can also propagate hydrangeas by collecting and sowing hydrangea seeds. Growing hydrangeas from seed is exciting because seed grown hydrangeas are unique. They are not clones of their parent plants and you don?t really know how a seed will turn out. Each of your seed grown hydrangeas will be considered a new cultivar. - You can start sowing hydrangea seeds immediately after you harvest them. Alternatively, save them in a cool place until spring and start sowing them then. In either case, surface sow the seeds in a flat filled with potting soil. Keep the soil moist and protect the seeds from cold and wind. They normally germinate in about 14 days.