Hi MM, I have grown two different breeders version of Russian Mammoth sunflower seeds.
Burpees and Park Seeds…they both grow very fast. They get to about 10 to 12 feet tall. Their flowers are as big as a very large dinner platter! They look spectacular when mature. Be aware that any strong wind will easily snap the stem because of the weight of the huge flowers. I use stakes on some of mine so they can withstand storms.
I also like to grow smaller varieties in containers. Here is one of my favorites: Chianti sunflower
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