Gardening is near and dear to me, so I love to see it show up on HN. Thanks for sharing :).

A couple points of feedback that I noticed so far:

1. I wrote a comment here in response to what you said about the tradeoff between growth rate and growth quality: https://news.ycombinator.com/item?id=50415982

2. In your section on photoperiodism (https://jrcpl.us/contrib/2020/gardening-for-engineers/#photo...), it seems the examples are backwards. Ie, lettuce is a long-day plant that flowers when days are long, mung bean is a short-day plant that flowers when days are short.