The accompanying photograph shows my Sunflower crop this year. It is very disappointing because of the height. This variety of Sunflower is supposed to reach heights of 8 to 10 feet but, as you can see, my plants are nowhere near that. This is why I came here. I need advice on how to maximize the height of my Sunflowers next year. How can I improve the probability of adding 4 to 5 feet to the height of my Sunflower plants next year? I live in Coastal San Diego.