About Plant Porch

What it does

Plant Porch turns the numbers indoor gardeners meet, such as PPFD, lux, DLI, VPD and the N-P-K on a fertiliser label, into plain answers: how much light your plants get, how long to run a grow light, how much feed to mix, whether the air is too dry, and how much seed to sow.

How it works

Every calculation runs in your browser. Nothing you type is sent to Plant Porch or anyone else, and once a page has loaded its calculator keeps working offline. There is no sign-up and there are no ads.

Where the numbers come from

Each formula, conversion factor and target range comes from a named source, listed at the foot of the page that uses it: university extension publications from Virginia Tech, Purdue, Missouri, Iowa State, Utah State, Michigan State, Wisconsin, Penn State and UC IPM, the FAO's vapour pressure equations, Apogee Instruments' light conversion tables and Johnny's Selected Seeds' microgreens trial. Where we could not find a source, we left the number out.

What it is not

The results are estimates for typical plants and lights. A PAR meter beats any lux conversion, your plants' growth is the final test of any light or feeding plan, and a fertiliser's own label directions come first.

Page-view counts

The site uses Cloudflare Web Analytics to count page views. It does not use cookies or track you across sites, and it never receives what you type into the calculators. The privacy page has the details.