Roots Calendar

a 13 month calendar app

Free · Designed for iPad. Not verified for macOS.

Reconnect with natural time. Track your days by the ancient Celtic Tree Calendar — 13 months, each named for a sacred tree. Moon phases, sun times & events. Roots Calendar reimagines how you experience time. Built on the Beth-Luis-Nion system, a 13-month calendar where every month has exactly 28 days and bears the name of a tree. Roots Calendar runs alongside your Gregorian life while offering a quieter, more seasonal rhythm beneath it. 13 MONTHS OF 28 DAYS Every month is identical in shape: always exactly 4 weeks, always starting on the same weekday. No more irregular months, no more counting days on your fingers. Beth (Birch) through Ruis (Elder), each with its own tree, its own keyword, its own character. YEAR DAY Between the last month and the first lies a single nameless day — Year Day. A threshold. A pause. A moment outside the normal count. YOUR CALENDAR, YOUR EVENTS Add events to any day. Color-code them. They stay on your device — nothing is sent anywhere. GOOGLE CALENDAR SYNC Optionally sync with your existing Google Calendar. Your Roots events appear alongside your regular appointments, mapped by Gregorian date. MOON PHASES See the current moon phase for any day, calculated locally with no external API. CELTIC FESTIVALS Samhain, Imbolc, Beltane, Lughnasadh and the solar festivals appear automatically as read-only markers in your calendar. MULTIPLE VIEWS Month grid, week, 3-day, day, and schedule views. Switch instantly from the menu. PRIVACY FIRST All event data is stored locally on your device using SQLite. No account required. No data collection. OPEN SOURCE Roots Calendar is open source (GPL-3.0). The full source is available on GitHub. — The Beth-Luis-Nion calendar is a 20th-century poetic and spiritual tradition, drawing on genuine Celtic materials — the Ogham alphabet, medieval Irish tree-lore, and the lunisolar Coligny Calendar. It was articulated in its modern form by Robert Graves in The White Goddess (1948). It is not a recovered ancient Druidic system, but a living practice with its own rich lineage.

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Home screen with moon phases Recurring events for x days or x weeks Improved contrast dark mode

Version 1.0.2

The developer, Sebastiaan Castenmiller, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

    The developer does not collect any data from this app.

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    Accessibility

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    Information

    Seller
    • Sebastiaan Castenmiller
    Size
    • 31 MB
    Category
    • Lifestyle
    Compatibility
    Requires iOS 13.0 or later.
    • iPhone
      Requires iOS 13.0 or later.
    • iPad
      Requires iPadOS 13.0 or later.
    • iPod touch
      Requires iOS 13.0 or later.
    • Mac
      Requires macOS 11.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 1.0 or later.
    Languages
    • English
    Age Rating
    4+
    Copyright
    • © 2025 Sebastiaan Castenmiller
  • Developer Website
  • Privacy Policy

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