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Great! We love sunflowers,Great! We love sunflowers, too.  There are many varieties with different heights and bloom time. It's perfectly normal for sunflowers to be late bloomers. Check the seed pack to see the "days to maturity" to know when they'll bloom. As a first-timer, it may also help you to read the comments below.

2015 Special Edition Garden GuideCooking Fresh with The Old Farmer's AlmanacThe Almanac Monthly Digital MagazineWhat the heck is a Garden Hod?