Answer: Planting them later won't help. The problem is the potential for frost and the fact that sunflowers begin to fade about that time. I suppose you could try a planting with a variety of sunflower types--especially those that form multiple heads--and hope for the best. But I would have a backup plan in place. It's really chancy. I grew sunflowers for my wedding last summer, and they were at their peak in late August (in Vermont). By October they had all gone by.
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