Depends on the type of sunflower. The bigger the sunflower the longer it will take to bloom. In other words for example, the Mammoth sunflower stands 6-10' tall so will take until fall to bloom, the teddy bear sunflower stands about 2-3' tall and will bloom probably in August, possibly late July. So it just depends. If you have the seed packet it would tell you on there, if you don't and you really want to know, then go to a walmart or kmart that still has seed packets and see what it says on there. If you have neither then try to remember the size of the seed, little ones are smaller plants, bigger seeds are the bigger plants. Hope this helps!!