The plant life cycle begins with a seed. This seed will sprout and produce a tiny immature plant (seedling) which will further mature. This maturation would result to reproduce again and start a new life cycle. These information are necessary to be known in order to have a definite time for harvest and/or to prevent wastage of time. Same as for the knowledge of the mode of reproduction, it could also save money.
Plants may grow annually, biennially, and perennially, and may produce sexually and asexually. It is more practical to know what type of behaviour that your plant exhibits. One good example is the Oryza sativa. This cereal crop reproduces sexually and grows/ can be harvested annually. For an instance, that the farmer thought that this crop could be harvested as soon as possible, he might ended up harvesting unripe products resulting to the loss of income and wastage of time and his effort. What if this farmer thought that the crop he grew could be appropriate to undergo asexual methods of reproduction? This phenomena could only be just a waste of time and effort.
In some cases, knowledge of the growth habit could greatly affect the production of a given crop. It is essential to determine whether the crop you are going to grow is a vine, herb, shrub or a tree. One main reason could probably be, to know how to properly take care of this crop and to efficiently maintain its health. Let us use the example above. Rice is an herb type of plant. It could not grow as tall as a tree. But what if the farmer knew that a rice plant could grow as tall as a coconut tree? He might be putting fertilizers over and over again to obtain his desires.