“We went on Craigslist and started saying 'hey, we're looking for people to weigh their plants every day twice per day for a couple months.' We had hundreds of responses. People thought it was cool to be doing citizen science — we ended up with people in Berlin and Sydney.”

Crowdsource training data on Craigslist — citizen-science weight-tracking

Greg needed global plant water-loss data to train its ML model. Rather than build a warehouse, Alex hit Craigslist and got hundreds of volunteers — including across hemispheres (which mattered for solar-radiation modeling). The product's ML core was trained on data they didn't pay for, contributed by people who liked the mission.