Nenrin

A calendar does not look at the tree

Most care calendars say which month to prune. A bonsai does not read the calendar. What a tree needs depends on its species, on the stage you are training it through, and on what the tree is doing right now. Two black pines in the same month need different work if one is being thickened and the other is being refined.

Nenrin takes those three as its input and works forward from the tree, rather than backward from the month.

Timed by stage, not just by species

Each tree is set to one of four stages — development, structural, refinement, maintenance. Work is attached to stages, so jobs that do not apply to the stage you are in never appear. Candle cutting shows on trees in refinement; hard cutback shows on trees in structural work.

The date you change a stage is kept. Past records hold the stage they were made in, so moving a tree forward never rewrites the meaning of its history.

What you see corrects the timing

Record that the buds are moving, that the shoots have extended, or that the foliage has hardened off, and the next job re-anchors to your tree instead of to an average date. Not "repot in March" but "repot when the buds move".

Trees with no observations run on the standard timing derived from your region settings (hemisphere and climate zone). Observations are never required — the more you add, the closer the schedule sits to your tree.

30 species, keyed to their Latin names

The species guide ships with 30 entries. Every one is keyed to its Latin binomial, so names never drift when you change language. Search matches both the Latin name and the common name in your language.

International bonsai terms such as jin, shari, nebari and yamadori are kept as they are, with a short gloss in your language in brackets. Translating them away would break the link to books and to practitioners in other countries.

The interface is available in 34 languages, including right-to-left layout for Arabic and Hebrew.

This week, and the year

This week gathers every tree you keep and lists the work that can be done now, one card per job, with the window it is best done in. Log it, or push it to later. Anything overdue is shown separately.

The year is a seasonal calendar showing which tree is due for what. Internally the seasons are held as phases — dormancy, pre bud break, early spring and so on — and mapped to months from your hemisphere and climate zone. The southern hemisphere is a setting, not a workaround.

Climate adjustment, and frost warnings

With Premium, timings shift with the weather where the tree stands. A season warmer or colder than the same period last year is converted into a number of days, and the schedule moves by that much. Forecast overnight lows produce a frost warning.

When this is on, Nenrin sends the tree's coordinates to Apple's WeatherKit and receives the weather for that point. That exchange is with Apple, not with the developer. Frost warnings are built by Nenrin from forecast minimum temperatures — they are not a republication of any meteorological service's alert.

With climate adjustment off, none of that traffic happens, and the standard calendar from your region settings still runs on the free tier.

Free and Premium

Nenrin Premium is an auto-renewing subscription, offered monthly or yearly. The yearly plan starts with a 7-day free trial. Prices are shown in the App Store and on the purchase screen in the app.

Nothing is deleted if your subscription ends. Trees beyond the third are not removed: they stay readable, exportable and deletable, and only new entries beyond the free limits are paused.

Three kinds of export, and what each can do

The ledger export is free, so your records stay available as a table even after a subscription ends. A ledger is not a backup — there is no path that reads it back, and the app says so where it offers it.

How your data is handled

Nenrin has no account. There is no advertising SDK and no analytics or tracking SDK, so the developer has no way of knowing how the app is used. Trees, records and photos are stored on your device and are not sent to the developer, who runs no server.

Two things do go over the network. One is climate adjustment, described above (Apple WeatherKit). The other is Premium iCloud sync, which stores your trees and records in your own iCloud private database, where the developer cannot read them. Both are optional.

Location permission is optional. Set the hemisphere and climate zone by hand and every calendar still works.

What it does not do

• It does not identify species or diagnose health from photographs.
• It does not recommend soils, fertilisers or products.
• It does not tell you that you should do a job. It shows the window the job usually falls in.
• It does not translate the notes you write.
• It does not republish meteorological alerts. Frost warnings are built from forecast minimum temperatures.
• It carries no advertising.

Please note

Bonsai practice varies by school, by region and by practitioner. The job names, the stage divisions and the seasonal windows in this app record that such practices exist; they are not a guarantee of accuracy and they are not horticultural advice.

Timings are a starting point. Always judge against the tree in front of you.

Requirements

iPhone and iPad running iOS 17.0 or later. On iPad in landscape the tree list and the detail view are shown as two columns. Available in 34 languages. Weather data is provided by Apple Weather.