About Sprout & Spectrum
An independent grow light publisher that compiles published specifications, does the arithmetic in view, and says plainly what it has not tested.
What this site is
Sprout & Spectrum covers one category exhaustively: grow lights for people growing indoors at home. Seed trays in a basement, houseplants on a windowsill in January, herbs on a kitchen shelf. Not commercial horticulture, not tents, not production.
The category is well served by two kinds of publisher and badly served in between. On one side are sites that will tell you a light is “full spectrum” and stop. On the other are the manufacturers themselves, who publish real specifications and have every reason to present them favorably. What almost nobody does is take the published numbers, divide them, and report what the result actually means for a shelf in a spare room.
That is the whole job here.
What we refuse to claim
Everyone in this category says they tested twenty lights. We have not tested any, and we say so on every page rather than in a disclaimer nobody reads.
We have not owned, unboxed, plugged in or measured any fixture on this site. We have no test lab, no quantum sensor and no integrating sphere. Claiming otherwise would be the easiest thing in the world to write and the easiest thing in the world for a competitor to disprove.
We also accept no free products, take no sponsored placements, and have no relationship with any manufacturer we cover. There is nothing to sell in those categories, which is why zero is the right number in all of them.
What we do instead
Four things, and every one of them is reproducible by a reader with the same source pages:
- Compile every published specification from the manufacturer’s own product page, not from a retail listing. Retail listings inflate wattage and omit photon figures; brand pages usually do not.
- Divide the numbers against each other. When a brand publishes both photon output and efficacy, one should produce the other from the wattage. Sometimes it does. That check is the single most useful thing we do.
- Compute coverage and running cost in view. Every arithmetic step appears on the page in a box, so you can re-run it or catch us getting it wrong.
- Report what is missing. Three of the nine fixtures we cover publish no photon data at all, and two of those are best-sellers. We name that on every page they appear on, including the ones we recommend.
The full procedure, including the formulas and the one assumption we make, is on the methodology page.
Who writes it
That framing is deliberate and it is the honest one. I am not a horticultural scientist, I hold no certification in lighting or plant physiology, and I have not spent a decade in the industry. What I have is an interest in the category, a willingness to read spec sheets nobody else reads, and a rule against writing down a number I cannot attribute.
Plenty of sites in this space lead with credentials. Some of those credentials are real. The ones that are not are the reason we describe the byline this way instead of dressing it up — a claim you cannot verify is worth less than an admission you can.
Where the authority actually comes from
Not from us. From University of Minnesota Extension, University of New Hampshire Extension, Iowa State University Extension, Virginia Cooperative Extension, the peer-reviewed literature on light spectrum and plant growth, the US Energy Information Administration for electricity rates, and the manufacturers’ own published specifications.
Every one of those is named and linked in the sources block at the bottom of the page where it is used, with the date we consulted it. If we cannot attribute a number, it does not go on the site.
How it is funded
Amazon Associates commission on qualifying purchases made through links on this site, at no extra cost to you. That disclosure sits at the top of every page that carries a buy link, above the first link rather than in the footer. The complete arrangement — including what it does not influence — is on the affiliate disclosure page, and the rules we hold ourselves to are in the editorial policy.
Getting in touch
If a number on this site is wrong, tell us and we will correct it and say that we did. If a manufacturer has published a figure we reported as missing, send the link and we will update the page. Email info@sproutandspectrum.com or use the contact page.
Sprout & Spectrum is published by Slate Mill Group.