The reproductive phase of a sunflower begins in June and ends in July or August, and the blooming phase lasts around 20 days. You can tell the seeds are ripening when the back of the sunflower head turns yellow. The bud may initially have a star-like appearance, but once the reproductive phase is complete, you’ll see your bud transform into the tall-stemmed, yellow-bloomed plant you know so well.

Sunflower Yet to Bloom

Sunflower Waiting to Bloom

Sunflower Almost Ready to Bloom