In cluster
A sunflower can grow about 4.5 in. in two weeks.
1. is a sunflower hard to grow
it takes about 80 to 120 days (all summer) for a sunflower to grow.
they usually grow any were you want them to grow
They grow
sunflower
Yes, you can replant sunflower seeds to grow new sunflowers.
They grow in clusters.
If you put a cut stem in the soil, it is unlikely the sunflower would grow. It would need to grow from seed.
No, you cannot plant a cut sunflower and expect it to grow because it needs to be planted with its roots intact in order to survive and grow.
You need to be growing the proper species. Not all of them will grow that tall. Look for "Giant" sunflower seeds.
A sunflower typically requires about 1 to 2 square feet of space to grow effectively.