Simple, show pros of why you want one.
Step-by-step explanation:
Convincing a parent is quite easy, but everyone's parent(s) are different. They key is trying to make a point in why it could put a better outlook on maybe say the kitchen, plants allow more oxygen in areas, so maybe it will be easier to breath, or maybe you like the look, say it'll be better for a more peaceful house. There are many variables into how you can persuade your parents. Maybe make a list of pros. Prove you can take care of plants by putting on in the kitchen and taking acre of it over time!