Planting Season For Sunflowers in Michigan

I've been waiting for the beginning of May because I had planned to get some giant sunflowers planted around the pool this year. The seed packets said to plant no sooner than May in Michigan, so I waited and waited. Yesterday was planting day. Here is what I hope to see in just a couple of short months. These "giant" sunflower seeds promise to grow to a height of 12 feet. They are lined up against the back fence of the pool area, so that they will provide the perfect backdrop. By the estimate on the package, they take approximately 75 days to reach their height.