Not a startup idea, but more of an open source idea. If I had 50-100k, I would hands-down quit my job and begin testing/logging ideal seeding/growing techniques for hydroponic herbs.
There already exists a plethora of information in regards to this for soil farming, but nearly no information exists out there for hydroponics. The main reason is because there's so many variants in the process. I would like to break down these variants and list the proper growing conditions and techniques for each variation in seeding techniques in order to pave the way forward for future startups in this field. I have worked with 2 highly funded hydroponic startups, and in both a huge capital expense went towards this research since since it isn't currently available. This is sad because all capital is burnt stuck in the research phase before any real progress can be made past that. Once the ground-work in terms of germination and growth can be establish, it will allow for much innovation to occur through efficiency, density, and cost.
If by any chance there is somebody out there whom would like to sponsor this research, feel free to reach out for further discussion. My email is in my profile.