In the green house of the botanical garden of the University of Erlangen I saw a bamboo plant, whose stalks had grown 38 centimetres a day.

I wanted to see this myself.
So I bought some seeds of dendrocalamus strictus and documented its growth in an animation.
I soaked the seed, which looks like oats, for two days in warm water. About four days after sowing the first sprouts appeared, with only one in ten seeds sprouting.
As you can easily see in the animation, 38 cm a day are impossible. Perhaps this might happen if the plant is older and new stalks grow out of the roots.
Provided that the thing doesn't commit suicide beforehand, since the stalk only grows longer but doesn't become thicker.

Seeds of the Giant Bamboo Dendrocalamus strictusafter 3 weeks - height 40cmafter 4 weeks - height 41cm

I would like to add that exactly four weeks afterwards a second, thicker stalk appeared. In the picture on the right you can see it as a small green point on the floor.
Herewith I'm going to finish my documentation of dendrocalamus strictus and turn to dendrocalamus moso. The seeds are just soaking. If the sprouting rate is more than 0 % a second animation might follow.

  Giant Bamboo