About — updated 2026-07

About The Garden Ledger

Search for "companion planting chart" and you will find hundreds of results that are, on inspection, the same chart. The same pairings, the same claimed benefits, in the same order — copied from site to site with no source and no indication that anyone ever checked whether they work. Most of them trace back, at some remove, to a single 1975 book containing no experiments and no citations.

That bothered us enough to do the work. We went through the literature crop by crop — extension publications first, peer-reviewed studies where extension coverage was thin — and graded every pairing we could find. The result is less satisfying than the charts: most companion planting advice has simply never been tested. But a real core of it holds up beautifully, and knowing which is which changes what you actually do in a garden.

A ledger records what happened, entry by entry, with the source of each figure written beside it. That is the design principle for the whole site. Every number you see — spacing, planting dates, per-square counts — derives from one dataset rather than being written by hand into pages that then drift apart. Every evidence grade carries a link to the publication it came from. And where a figure is an estimate rather than a sourced fact, we say so on the methodology page instead of letting it pass as research.

• Present folklore as fact. "Traditional" is the most common stamp on this site. That is an honest description of the field, not a failure of research, and we would rather publish it than pad the research column.
• Sell a grade. Evidence stamps are assigned from the literature before anything is linked. We don't take payment for a grade, a chart placement, or a mention.
• Gate the useful parts. The companion chart prints for free with no email wall. The tools need no account.
• Invent authority. We are not a university and don't pretend to be. The value here is in the sourcing and the grading being transparent enough that you can check our work — every claim links out to the publication behind it.

Display advertising and affiliate links on seeds, soil and garden equipment. Neither influences an evidence grade — several of the products most commonly sold on companion planting claims are ones whose premise we grade as unsupported. Full disclosure here.

We would genuinely rather be corrected than be wrong, and this is a field where new trials keep appearing. If you know of a study that would move a pairing from traditional to research, or from research to myth, we want it. Likewise if a spacing figure or a planting date looks off against your local extension service.

Write to corrections@thegardenledger.com with the crop, the claim, and the source. Corrections go into the dataset, which updates every page that uses the figure at once, and each record shows the month it was last compiled.