How we research guidance
Every task Gardenplanner suggests comes from a written rule, and every rule lists the sources it relies on. Here is where those sources come from, how the rules are checked, and what we can't know from here.
Where the guidance comes from
Our crop rules and guides are based on publications from US university extension services, the public advice services run by land-grant universities. Weather rules also use the National Weather Service (NOAA) for forecasts and station observations, NOAA's 1991–2020 US climate normals for typical conditions, and the USDA 2023 Plant Hardiness Zone Map for winter cold.
Each rule cites its sources, and each public guide numbers them, so you can read the original advice. You can see the sources for any task in the app under "Why this appeared", and on its public task explanation page.
How rules and guides are checked
We research rules and guides with the help of AI tools. A person then checks every threshold and timing claim against the cited sources before it ships. Our pages call this "Sources checked", with the month it was done.
None of our guidance has been reviewed by an extension-qualified expert yet. We are looking for reviewers such as extension educators and Master Gardeners. When a rule or guide is reviewed, its page will say "Reviewed by" with the reviewer's name and credential. Until then, treat thresholds as approximate, and check with your county extension office when timing matters.
Content is due for another check 18 months after it was last checked, and every page shows when that was.
Detailed and general guidance
Some crops (tomato, cucumber, sweet pepper, green bean, carrot, summer squash, onion, hot pepper, lettuce, pea, zucchini, snap pea, snow pea, fava bean, apple, lemon) have detailed guidance: researched rules written for that crop. Every other plant, including custom plants you add yourself, gets general guidance: we still tell you about frost, heat, and dry spells, based on how well that kind of plant tolerates cold, but we never promise crop-specific timing.
What the weather data can't tell us
- The nearest weather station can be several miles away and measures open ground. Your garden may be warmer, cooler, wetter, or drier.
- Rain at the station doesn't mean your beds got the same amount, and forecast rain hasn't fallen yet. We never treat forecast rain as watering.
- Frost can form even when the forecast low is a few degrees above freezing, especially on clear, calm nights and in low spots.
- We can't see your soil, shade, or plants. When a task depends on them, we ask you to check instead of guessing.
- Your hardiness zone describes typical winter lows. It helps with trees and perennials. It doesn't set vegetable planting dates.
When your own notes disagree with the station, we go with your notes.
If something looks wrong
Tap "Doesn't apply" and choose "Seems wrong for my area". We review those answers by region. You can also write to us at hello@gardenplanner.app.