Rain grows.
From 1 mm every plant in its growing season grows one stage – two from 10 mm – and the stream rises.
≥ 1 mm · 10 mm counts twice
Behind this card: the simulated garden on 1 Jun 2026 – real weather of that day.
Day 38 · 5 Nov 2026 · Heilbronn
A garden that grows with the weather.
Every morning at 08:53 a Claude routine reads yesterday's weather in Heilbronn. Rain grows, sun ripens, frost stops, storm fells – then the gardener makes one choice, and exactly one commit.
The four rules
Rain grows. Sun ripens. Frost stops. Storm fells.
Every morning the routine records yesterday's real weather in Heilbronn and boils it down to one condition. The condition acts on the garden first – only then does the gardener get a turn.
Sun ripens.
6 hours of sunshine on a dry day open blossoms and ripen fruit. The stream sinks and the sand bank grows.
≥ 6 h of sunshine, dry
Behind this card: the simulated garden on 3 Aug 2026 – real weather of that day.
Frost stops.
A night below 0 °C stops all growth, freezes the stream and makes the annual flowers wilt. Nothing can be planted in frozen ground.
night below 0 °C
Behind this card: the simulated garden on 2 Dec 2025 – real weather of that day.
Storm fells.
Gusts of 62 km/h or more blow away blossoms and fruit. A grown tree may fall (at most one every 60 days) – otherwise a paper boat strands on the sand bank.
gusts ≥ 62 km/h
Behind this card: the simulated garden on 17 Mar 2026 – real weather of that day.
Snow covers the garden and makes snowmen possible; a grey day changes nothing – a good day to water. All rules of the garden →
Timelapse · the real garden
Day000
28 Sep 2026
Genesis an empty bed
Scroll to replay every day since the empty bed.
Day 0
An empty garden bed by a stream
Dark soil, a trickle of water and one question: what will the weather in Heilbronn make of it?
The weather so far
Heilbronn is the gardener's only boss.
Every value below is the real weather in Heilbronn on the day before each commit – fetched from Open-Meteo by the routine and stored in world.json.
- Rain days1072 mm in total
- Sunny days21217 hours of sunshine
- Frost and snow00 of them with snow
- Storm days0gusts up to 54 km/h
- Warmest30.0 °C28 Sep 2026
- Coldest0.1 °C2 Nov 2026
Hover a day – or focus the calendar and use the arrow keys.
How it grows
Tended by a routine, one commit at a time.
The weather is real and nobody controls it. The gardener is a scheduled Claude routine – inside a strict frame of code, tests and continuous integration. Everything it does is public.
- 08:53
The routine wakes up
A Claude routine starts in the cloud, every day at 08:53 in Heilbronn.
- 01
Is today already done?
If there is a commit for today it stops. Running twice changes nothing.
- 02
Ask the sky
npm run day -- weather fetches yesterday in Heilbronn from Open-Meteo – or repeats the last day, marked.
- 03
Let nature act
npm run day -- plan shows what the weather does to the garden and every choice that is left.
- 04
Choose and write
Claude plants, builds, waters, harvests or rests – and writes one line of lore.
- 05
Exactly one commit
A pull request with one commit – once CI is green it is merged into main.
- 06
The site grows too
The merge redeploys this website. The garden you see is the commit of today.
Today's commit
$ npm run day -- status { "day": 38, "done": true } $ git log -1 --format=%s Day 38: Watering the young pine (grey 9.7 °C) # one day of weather · one choice · one commit
The routine's instructions are a file in the repository – versioned, reviewable, open.
Logbook
A chronicle, one line per day.
Every day gets a line: yesterday's weather, what it did, and the gardener's one choice. Read backwards, the lines become the garden's history.
- DAY 038Watering the young pine
5 Nov 2026 · ☁️ 6°/10° · Another grey, breezy day passes without a drop of rain, so the gardener fills a can at the rain barrel and waters the young pine by the sundial. - DAY 037Tulip bulbs beneath the apple tree
4 Nov 2026 · ☁️ 6°/8° · Under a low grey sky and a gusty wind, the gardener kneels beneath the young apple tree and tucks a tulip bulb into the cool soil. - DAY 036Watering the young pine
3 Nov 2026 · ☀️ 7.0 h · The night comes close to freezing and the stream stays dry, so the gardener carries a can from the rain barrel to the young pine beside the sundial. - DAY 035A sundial beneath the pine
2 Nov 2026 · ☀️ 7.8 h · After twenty sunny days on record, the gardener sets a stone sundial beneath the pine, and its shadow creeps across the hours of a clear, cold afternoon. - DAY 034Tulip bulbs in the west of the garden
1 Nov 2026 · ☀️ 6.2 h · A cold, clear day keeps the ground firm, and the gardener sets a tulip bulb in the west of the garden, close beside the shed, to wait for spring. - DAY 033Watering the young willow
31 Oct 2026 · ☀️ 8.0 h · The stream bed lies dry for the first time, so the gardener draws water from the rain barrel and carries it to the willow in the middle of the garden.
Chapters
How it works, in four short stories.
CHAPTER 01 · 3 MIN
Why let the weather decide?
A garden nobody controls: one real day of Heilbronn weather, one choice, one commit – forever.
CHAPTER 02 · 5 MIN
Plants from grammars
Lindenmayer systems, a 3D turtle and growth levels: why every rain day adds a ring of branches.
CHAPTER 03 · 5 MIN
Rain grows, sun ripens
Six conditions, a stream that widens, ice, snowmen and storms that fell trees – the rules of nature.
CHAPTER 04 · 4 MIN
A day in the life of the routine
What happens between 08:53 and the merge: the weather call, the plan, one pull request, one commit.
Archipelago
One garden is a mechanic. Three are an archipelago.
This garden grows with the weather. Two sister islands grow by other forces – their own rules, and the wishes of strangers. Same routine, same one commit a day.
