Watering is easy but one can overcomplicate it. Each plant has different water needs. Screw it up, you get likely get root rot or dry soil.

An engineer might analyse the soil and the plant water needs. Inject water to right levels, or set a timer. These settings need to be readjusted constantly without a hydrometer.

I found an ancient solution that worked incredibly efficient and required no electricity and far cheaper than spending hundreds on electronics. Ollas. The science is called capillary action.

I went a step further as an engineer, and did DIY terracotta pots + silicone. Added a testing stage, of course. Filled pots and sealed it over night. If leaking from seal, more silicone. For filling them up, I used irrigation fittings hooked up to a tank. If I wanted to, I could use rain water into tank (with overflow). That way watering is a fully automated pipeline.

I don't have a picture on hand but others have done it like this: https://www.abc.net.au/gardening/how-to/olla-watering-pots/1...

Other fun topics I looked into:

- Companion plants (avoid spending on pesticides)

- Crop rotation (avoid spending on fertilisers)

- Composting (for compost)

Those are not easy to automate but other topics to make it far cheaper to grow crops without trips to nurseries.