How we work
Where our data comes from, how we label it, and what we will not claim.
Last updated August 2026
Where the data comes from
We build from manufacturer documentation and specification sheets, product manuals, retailer listings and shipping terms, publicly observable pricing recorded over time, and — as this launches — reports from people who actually own the greenhouse.
Where we can point a specification back to the document it came from, we do. Where two sources disagree — and they often do — we would rather show you the disagreement than quietly pick a winner.
Where a manufacturer publishes nothing, we say so. A missing wind rating is recorded as not publicly documented. It does not get filled in with an estimate, a competitor's number, or a plausible-sounding guess.
The four labels
Not all information is the same kind of thing, and blurring the difference is how buyers end up trusting a marketing claim. We keep these separate:
| Label | Meaning |
|---|---|
| Manufacturer specification | Published by the manufacturer. We are reporting their claim, not endorsing it. |
| Owner reported | Submitted by an identified owner about a greenhouse they installed. |
| Tested by GreenhouseGrid | Something we physically tested. Used only when literally true. |
| Editorial analysis | Our interpretation of sourced information. Opinion, marked as opinion. |
Prices, shipping and total cost
For large freight items the advertised price is often the wrong number, so we work toward the delivered price — what it costs to get the greenhouse to your address. Where a retailer only quotes freight at checkout, we say quote required rather than treating it as free, because assuming zero would flatter whichever seller hides its shipping cost.
Total project costs are estimates presented as ranges, not quotes. Real costs vary enormously with site conditions, region, and how much you do yourself.
Price history reflects what we observed and when. Our record starts when we started recording, not when the product launched — and where we have too little history to say anything meaningful, we say that rather than dressing up two data points as a trend.
Independence
Commission rate is not an input into any ranking, comparison, score or specification. We will list retailers who pay us nothing when they have the better delivered price or the better fulfillment record, and any paid placement will be labeled as paid and kept out of editorial ordering.
What we will not claim
- We do not provide engineering certification.
- We do not confirm local building-code or permit compliance.
- We do not convert a manufacturer's wind rating into a safety guarantee for your site.
- We do not describe a product as tested unless we tested it.
Corrections
We will get things wrong. Specifications change between product generations, retailers revise shipping terms, and manuals get updated without notice. If you find an error — especially if you are a manufacturer or retailer looking at your own product — tell us and we will fix it.