GRDN
Several gardens, real weather, and jobs that come from an agronomic model rather than a timer. Coming soon to the App Store.
Several gardens, real weather, and jobs that come from an agronomic model rather than a timer. Coming soon to the App Store.
Most gardening apps water on a schedule. That is the wrong model: a schedule cannot know that it rained on Tuesday, that the bed faces north, or that the greenhouse never gets rained on at all. GRDN keeps a soil water balance for every planting — how much water the soil holds, how much the weather has taken out of it since it last rained, and how deep that particular plant's roots go — and only asks you to water when the number says the plants have genuinely run short.
A kitchen bed, a greenhouse and a windowsill are three different places with three different needs, and lumping them together is what makes generic advice useless. Each garden in GRDN carries its own environment — open ground, raised bed, container, cold frame, greenhouse or indoors — and these are not labels. They change the maths. Rain counts for the open bed and not for the greenhouse. A container dries faster and freezes from every side, so it is colder than open ground, not warmer.
Each garden has an aspect and a slope. A south-facing wall gathers more sun through the day, runs warmer at night and dries faster than a north-facing bed twenty metres away — so it gets more water and a different frost risk. Below the equator this flips, and GRDN flips with it: south-facing is the shady side in São Paulo.
GRDN knows what each plant can take, and what tonight is going to do. When those disagree it tells you the evening before, while fetching a fleece or bringing the citrus in is still a thing you can do — not the next morning, when it is a post-mortem. Your last and first frost dates are computed from fifteen years of weather at your own location rather than read off a hardiness zone drawn across half a country. In Oslo that lands on the 17th of May, which is where Norwegian gardeners have always put it.
"60–85 days" on a seed packet assumes an average summer. GRDN accumulates growing degree days from the temperatures your plants have actually had, so a cold fortnight pushes the harvest back and a warm spell pulls it forward. If you look at a plant and disagree with the model, tell it what stage the plant is really at — your eyes outrank the arithmetic, and the clock re-anchors to what you saw.
Over 41,000 plants by name across twelve languages, in the app, working with no signal at all. Search in Polish and GRDN searches Polish; if it finds nothing, it says so and offers to look under the botanical name or another language rather than quietly showing you Norwegian results. A smaller, hand-written care layer carries the real horticultural data — crop coefficients, rooting depth, frost tolerance, degree-day thresholds — and where a plant has no care guide yet, GRDN says exactly that instead of inventing advice.
Nothing horticultural in GRDN is made up. Crop coefficients, depletion fractions and rooting depths come from FAO-56, the UN's irrigation and drainage standard. Degree-day thresholds come from university extension services, recorded with the base temperature they were derived at. Reference evapotranspiration is computed with Hargreaves–Samani, which is FAO-56's own documented method when radiation and humidity are unavailable. Plant names come from GBIF and Wikidata; frost dates from NASA POWER; weather from Apple Weather. Every curated value carries a source, and the whole curated dataset is published under CC-BY-SA.
No account. No analytics. No trackers. No third-party SDKs. Your gardens, what you planted and everything you have done to them live in a single file on your device. The only thing that goes anywhere is a coordinate handed to Apple's weather service to ask what the weather is doing — captured to the nearest kilometre, because a garden is not a street address.
GRDN is free, and the free version is the whole engine: real watering advice, real frost warnings, the entire plant catalogue, and the frost alert on your phone the evening before. Withholding a frost warning until someone subscribes would be letting plants die for money, so we do not. The free tier covers one garden and ten plants — a balcony with six pots never needs to pay us anything.
GRDN Pro adds: