543 figures and statements about indoor light, transcribed one at a time from 80 publishers. Units left exactly as each one writes them. Every row links to the page it was read on.
Writing anything about how much light a houseplant needs means reading a lot of extension services, and they do not agree. This file is that reading, done once and written down: one row per published statement, with the figure in the unit the source uses, the sentence as it was published, a link to the page it came from, and the date it was read.
Nothing here is converted. A source that writes foot-candles stays in foot-candles; one that writes lux stays in lux. Converting is where provenance goes to die, and a reader who wants both can convert once, knowingly.
A collection like this is worth having because the sources contradict each other, and the contradictions are invisible if you only ever read one of them:
| The same question | One publisher | Another |
|---|---|---|
| Coldest a ZZ plant should get | 60 °F | 50 °F |
| Coldest a peace lily should get | 60 °F | 40 °F |
| Where a “low light” band starts | 25 fc | 75 fc, and 100 |
| Humidity a houseplant wants | 40–50% | 70–80% |
| What a north windowsill measures | 200 ft-c | 75 foot-candles |
Every figure in that table is current, published, land-grant extension advice, and each line is two or three of them answering the same question differently. The file lets you see how wide the published band actually is before you quote any single figure from inside it.
It is not a survey of the literature. The rows were collected because our own guide pages needed them, so the coverage follows our questions rather than a sampling frame, and a publisher that says something we never had to ask about is simply absent. It carries no weighting, no quality score and no attempt to reconcile anything: two rows that contradict each other both stay.
It is also not our own measurements. Those are a separate file — readings we took with a meter in real rooms — and the two are deliberately kept apart, because what somebody published and what a meter said in a living room are different kinds of claim.
The compilation is published under Creative Commons Attribution 4.0: which sources were read, how the rows are structured, and the links. Use it, reprint it, build on it, commercially or not. The one condition is attribution, and this line covers it:
The file is archived with a DOI on Zenodo and mirrored on Kaggle and Hugging Face, alongside our species light tiers and measured readings.
The quoted sentences are not ours to license. Each one remains the property of the publisher named in its row. They are short excerpts, reproduced so a claim can be identified and checked, and every row carries the link back. If you republish the file, keep the source_url column with it.
source_url plus value_as_published is usually what you want to group on.value_as_published is a string, not a number, because “800–2,000+ lux” and “four or more hours of direct sun” are both answers people publish.This is the third open file we publish. The other two are our own light-meter readings from real rooms and the light tier we file each species under. Between them: what others published, what we measured, and what we concluded.