Plant can take 75 to 90 days to mature. If you want a fast growing plant that will mature in a short time then plant radishes. Some radish varieties can be ready to harvest in 22 or 23 days.
If you plant seeds they grow rather fast 40-65 days most are close to maturity. Keep them moist with water.
sunflower
they get 500 tons of water
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
the roots of the sunflower grow rapidly so this can cause it to store rain to grow even tho being chopped in half
In cluster
If you put a cut stem in the soil, it is unlikely the sunflower would grow. It would need to grow from seed.
You need to be growing the proper species. Not all of them will grow that tall. Look for "Giant" sunflower seeds.