Every niche is worthy & profitable if you can find out super low competitive keywords. As you mentioned your niche is plant, I want to add that many people are fascinated in that particular niche. That can be for business or decorating their houses. You can not only target plants, you can target planting tools, plant maintaining tools, medicines, fertilizers etc related to plants.
As I do keyword research from long period of time, I suggest you not to only focus on KD and determine it's easy to rank. You can search manually and see if there are any opportunity to be in the list even if KD is higher of the keyword. This is called in-depth research. Hope you got some decent ideas and now you can move on with that niche.
Earning opportunities: Google Adsense, Amazon, E-commerce etc