Asparagus growth speed is different during the day and at night.
During the day the average growth speed is 0.37 cm/hr.
At night it is 0.18 cm/hr.
So basically, the growth speed is doubled during the day compared with that at night.
The summary:
The sources:
1). 13.8 cm
2). 12.0 cm
3). 17 cm
4). 15.5 cm
5). 20.1 cm
6). 17.3 cm