This is my crop of giant sunflowers. I measured two of the sunflowers to be 12.5 and 12.6 feet tall before the blooms bent the stalks over. I planted the plants to create a tunnel that my son could walk through. Since the flowers were close together, they competed for sunlight creating thin tall stalks. Thin stalks are not able to hold the flowering seeds as well and will break the stalks as they mature. Next time I will allow more space between plants.