Yes, “mammoth” is definitely a good word to describe this flower, since it grows over 6 feet tall and sometimes up to 12 feet! The flowers alone, atop their towering stems, can grow to be a foot across.
Mammoth Grey Sunflowers require full sun and can handle dry conditions. They do well in zones 3-9 and are quite easy to grow—they also aren’t picky about soil quality.
A big plus of these flowers is that they can provide a delicious snack, either for you or birds you want to attract to your yard. You can remove the seeds from the sunflower heads once they have drooped and dried out by scraping seeds off with a spoon or a gloved hand and into a paper bag or tray.