Ne’er cast a clout till May be out.
Garden planner & season journal · iPhone, iPad & AndroidThe last frost date your garden actually gets.
Most garden apps read your last frost off a map. Maythorn reads it from the weather station nearest you, out of 30 years of daily records, and tells you which station and how far away it is. Then it keeps the season journal you are currently keeping on paper.
€19.99 once · one garden and this season are free · no subscription · also coming to Google Play
Sow when it is safe where you are, not where the seed packet is.
A coastal station and an inland one can sit seven weeks apart. That gap is the whole reason this app exists.
Pick it yourself or let the app find the nearest one. It never quietly interpolates: the station name and its distance stay on screen, so you can judge the number yourself.
What is safe this week, crop by crop.
The month view of your station's dates, not a national average. The median last spring frost, the one-in-ten-year late frost that careful gardeners plan against, and the first night warm enough for tomatoes and beans, translated into sowing windows per crop.
A window that has already closed is marked as passed, so nothing is planted on hope.
Turn on reminders and a Monday-morning note arrives in the weeks when sowing windows open at your station, plus one on the frost-safe morning. They are planned on your phone, without a forecast service.
Each crop's page also lists its traditional good neighbours and the crops to keep apart, labelled as what it is: gardeners' experience, not a measured result.
The notebook you already keep, in a form that survives the winter.
Sowed, potted on, planted out, harvested, per bed or per plant. Every past season stays, so you can put this March beside last March instead of trusting memory.
Rhubarb, asparagus, apple, blackcurrant. The plants that stay in the ground for years, kept beside the annual beds instead of in a second notebook.
With the unlock, every crop you grew in two or more seasons sits side by side: first sowing, planting out and first harvest per year, with your own last spring frost next to them.
Weigh a harvest if you like, in kg, g, lb, oz or pieces, and the journal adds up each crop's season. A harvest you did not weigh stays blank rather than counting as zero.
Log the frost nights you see, and your plot gets its own measured record.
You see which station the app used and how far away it is, and you can pick a different one. On top of that, logging the frost nights you actually get builds your plot's own measured record, which beats any station once you have a few seasons in it.
This works in every country, whether or not its station records are open yet.
€19.99
One-time purchase · yours to keep
Free: one garden, full frost guidance, and reading and export of every saved season.
- ✓Unlimited gardens and beds
- ✓Your last-frost median from at least three logged spring seasons.
- ✓Your seasons side by side, crop by crop
- ✓Perennials and fruit trees
- ✓Export stays free in both
- ✓Family Sharing on the App Store
Google Play is a separate purchase at the same one-time price. No account, and your garden stays on your phone.
Questions people ask first.
Where do the frost dates come from?+
From the national weather services: 30 years of daily minimum temperatures per station, turned into the median last frost, the one-in-ten-year date and the first warm nights. Every station is credited in the app with its licence. Nothing is estimated between stations, which is why the app shows you the distance and lets you disagree with it.
Is my country covered?+
Nineteen are: the Netherlands, Belgium, Germany, Austria, Switzerland, France, the United Kingdom, Ireland, Spain, Poland, Czechia, Sweden, Norway, Denmark, Finland, the United States, Canada, Japan and South Korea. Where a country's records are not open for this, Italy and Mexico today, the app says so instead of showing a date it cannot stand behind. The journal, the crop catalogue, the export and your garden's own frost record work everywhere.
What if my garden sits between two stations?+
You see which one it used and how far away it is, and you can pick a different one. On top of that, logging the frost nights you actually get builds your plot's own measured record, which beats any station once you have a few seasons in it.
Is it a subscription?+
No. One purchase, €19.99, with Family Sharing. The free version is a real version: one garden, this season's journal, the full frost window, and export.
Does one purchase cover both iPhone and Android?+
One App Store purchase unlocks Maythorn on your iPhone and iPad, with Family Sharing. The Google Play version is a separate purchase at the same one-time price. Your garden travels between the two as the file you export.
Can I get my data out?+
Yes, in both the free and the paid version. Your whole garden exports as a file whenever you want it.
How Maythorn is made
We develop our apps with AI tools for programming and translation. We use automated checks and device tests. oomny is responsible for the result, and a person answers support requests.
AI and data processing in this app
Maythorn works nothing out with AI. The climate figures come precomputed from open weather data and ship inside the app, and your garden journal stays on your device. The crop illustrations were made in advance with an image model; nothing is generated while you use the app.