A notebook with one column for each observation date can be rearranged into a table with one row per plant and date. The measurements need not change, but their layout does. A small invented example makes the relationship easy to check.
Start with two plants and two dates
Suppose plant A has heights of 10 and 12 centimetres on two stated dates, while plant B has 8 and 9. A wide table can place each plant on one row with separate date columns. A long table can use four rows and columns for plant, date, and height.
These values are illustrative, not experimental findings. In either arrangement, keep the unit explicit and retain the exact date rather than a label such as “later” whose meaning may be forgotten.
Verify the relationships after rearranging
Check that each plant-date pair still has the same measurement. Four values remaining in the file is not enough if one has become attached to the wrong plant. Also preserve any missing observations instead of dropping them without explanation.
Choose a layout according to the next task or the requirements of the analysis tool. Neither shape is automatically more truthful. The essential point is that restructuring changes organisation while preserving the relationship between each value and the observation it represents.