Russian Mammoth Organic sunflower seeds are CERTIFIED ORGANIC! Russian Mammoth heirloom sunflowers mature a little later in summer, but grow to an impressive 3m (10′) tall, with heavy heads that average 50cm (20″) in diameter. Plants benefit from staking as the heads get BIG. The seeds are large, tasty and edible, with the distinctive grey stripe seen on confectionery sunflower seeds. Just pick them, dry roast them in the oven and add optional sea salt. You will know the seeds are mature when chickadees start clinging to the downward pointing faces of the enormous flower heads. This is a fun plant to grow with young people as it becomes truly massive in just a couple of months. The seeds are large and easy to handle for little hands.