The Ogham tree calendar is a system that assigns each of the 13 lunar months to a specific tree from the Ogham alphabet, creating a year-long cycle of tree energies. It was popularized by Robert Graves in The White Goddess (1948), though its historical basis is debated.
The Months
- Birch (Beth) — Dec 24 - Jan 20: New beginnings, purification
- Rowan (Luis) — Jan 21 - Feb 17: Protection, vision
- Ash (Nuin) — Feb 18 - Mar 17: Connection, the World Tree
- Alder (Fearn) — Mar 18 - Apr 14: Foundations, oracular sight
- Willow (Saille) — Apr 15 - May 12: Intuition, lunar energy
- Hawthorn (hÚath) — May 13 - Jun 9: Cleansing, restraint
- Oak (Duir) — Jun 10 - Jul 7: Strength, doors opening
- Holly (Tinne) — Jul 8 - Aug 4: Challenge, balance
- Hazel (Coll) — Aug 5 - Sep 1: Wisdom, creativity
- Vine (Muin) — Sep 2 - Sep 29: Prophecy, harvest
- Ivy (Gort) — Sep 30 - Oct 27: Tenacity, spiral growth
- Reed (nGétal) — Oct 28 - Nov 24: Direction, harmony
- Elder (Ruis) — Nov 25 - Dec 22: Endings, transformation
Whether historically authentic or a modern reconstruction, the tree calendar provides a useful framework for seasonal divination practice — drawing the month's associated Ogham fid and reflecting on its themes as a regular practice.