What is the Celtic Tree Calendar?

by Linda Kerr

Copyright 1999 by Linda Kerr

The Beth-Luis-Nion Celtic Lunar Tree Calendar/alphabet consists of 13 lunar trees and five solar trees. The calendar is based on a lunar year as opposed to a solar one, and begins after the Winter Solstice. There are roughly 13 lunar months, which begin and end with the new moon; each lunar month is represented by a tree. The five solar trees represent the 4 seasons of the year, plus the Winter Solstice. The five solar trees are like 'umbrella' trees; they cover a larger portion of the year than the lunar trees do; usually about 2-3 months each.

The system is also used as an alphabet; using the Gaelic names for the trees, the first letters of the lunar trees are the consonants, and the five solar trees are the vowels. This alphabet, when written, is put down in marks, usually on a twig or branch, called ogham. This is an ancient system of writing, and there are almost as many ogham alphabets as there are rune systems.

This entire system; the lunar months, the solar seasons, the trees in both their English and Gaelic names, and the ogham, is the Celtic Lunar Tree Calendar. There seem to be two major Celtic Tree systems; the one that we, the Faerie Faith, use, is called the Beth-Luis-Nion system. Its calendar begins on the Winter Solstice, the months run from new moon to new moon, and the trees are Birch, Rowan, Ash, etc., as listed in the table below. The other system is called the Beth-Luis-Fearn. Its calendar begins at Samhain, November 1, the months go from full moon to fill moon, and the order of its trees is slightly different: Birch, Rowan, Alder, Willow, Ash, Hawthorn, Oak, etc.

Lunar Trees (Consonants):
Tree # English Name Gaelic Name Letter Glyph
1 Birch Beth B I am a stag of seven tines, or I am an ox of seven fights
2 Rowan Luis L I am a wide flood on a plain
3 Ash Nion N I am a wind on the deep waters
4 Alder Fearn F I am a shining tear of the sun
5 Willow Saille S I am a hawk on a cliff
6 Hawthorn Huath H I am fair among flowers
7 Oak Duir D I am a god who sets the head afire with smoke
8 Holly Tinne T I am a battle-waging spear
9 Hazel Coll C I am a salmon in the pool
10 Vine Muir M I am a hill of poetry
11 Ivy Gort G I am a ruthless boar
12 Reed Ngetal Ng I am a threatening noise of the sea
13 Elder Ruis R I am a wave of the sea
Winter Solstice Who but I knows the secrets of the unhewn dolmen?

Solar Trees (Vowels):
Tree # English Name Gaelic Name Letter Glyph
1 Silver Fir Ailim A
2 Gorse Ohn O
3 Heather Ur U
4 Aspen Eadha E
5 Yew Ioho I

Each of the 13 lunar months and 5 solar seasons also has its own particular 'glyph,' or line, from the Song of Amergin, an ancient poem said to have been chanted by the chief bard of the Milesian invaders of Ireland as he first set foot to the island in 1268 BC. This poem was reconstructed by Robert Graves in The White Goddess and related to the Beth-Luis-Nion alphabet, as shown in the table above.

Each of these lines speak of a particular essence of the lunar energies, and when studied in-depth, can help lead to a greater understanding of the tree month.

Using The Lunar Calendar With The Gregorian Calendar

Some may feel that the moon names, Birch, Rowan, Ash, Alder, etc., are just alternative names for the secular months of our modern-day Gregorian calendar. This is no more accurate than saying it doesn't make any difference whether someone was born under the sign of Scorpio or Libra, as they're both just names for that particular time of year, and don't have any bearing on the person involved.

The Lunar Tree Calendar, as practiced by the Faerie Faith, is more than simply a system of alternative names for the 12-13 cycles of the moon that occur in a solar year of 364 days. Each of the 13 moons in the calendar is named after a tree. The Birch moon is always the first, and they proceed in the order as shown in the table, with Elder always falling last. The calendar begins within a few days after the Winter Solstice, and always ends on the Winter Solstice, never going past that date. This is a fixed solar date: by fixed, I mean that this is the day when the night is longest and day is shortest. After this day, usually on December 21 or 22, the days will begin getting longer, and we enter a new solar cycle. This fact is recognized by our Gregorian calendar, which begins on January 1, 8-9 days after the Winter Solstice. Part of the reason for this brief delay in the Gregorian calendar lies in the 10 days lost when we converted over to the Gregorian calendar from the Julian calendar, in 1582 in parts of Europe, in 1700 by the Protestant German states, and in 1750 in America and Great Britain.

The date of the Winter Solstice is just about the only fixed point in the Celtic Lunar Tree Calendar, but we can approximate several other dates along the calendar. Let's talk about the length of the lunations: folklore tell us that a lunar cycle is 28 days, the same as a woman's monthly cycle. If you multiply 28 days x 13 lunations, and add in one extra day, you would conveniently get a 365 day year, which is a standard year in the Gregorian calendar (the true length of the solar year is 365.2422 days). But nature doesn't work in accordance with a set 365- day year. In actuality, a lunar cycle can range anywhere from 28 days to 30 days. If you have 13 moons of 29 days each, not even including any of the renegade 30-day moons, you'll have a year of 377 days (actually there are 12.368 lunar months in a solar year. Obviously, if you're trying to fit this lunar calendar system into the confines of the solar year as marked by the Winter Solstice, it just is not going to work.

So what do we do? Instead of trying to begin with Birch after the Winter Solstice and continue faithfully through to the end of Elder before ending the year, and thus having an Elder moon that continues into the next January, and having all sorts of problems with the calendar the next year, we end the year at the Winter Solstice, regardless of where in the lunar cycle we happen to be. No, it doesn't make for a nice neat calendar with exactly 13 moons of 28 days each, but we are trying to work with the natural system of things, rather than a man-made contrivance. Even the Gregorian calendar allows for the fluctuation of days over a period of time with its Leap Day.

That's the easy part. Now the hard part -- when do we begin the next lunar year? Well, obviously it's going to be shortly after the Winter Solstice. I'll give you a hint that pretty much takes care of the guess work. February 2, or Imbolc, always falls with Rowan moon, the 2nd lunation. So find February 2, and follow the lunar cycle back to the new moon. That is the beginning of Rowan moon. It then follows that the day before that new moon was the last day of Birch. Now, follow that lunation backwards. If you get to the new moon before you get to December 21, then you have an entire lunation for Birch, and the days between Winter Solstice and that new moon are the Days Apart. If you get to December 21 before you get to the new moon (working backwards, remember), then you've just got a short lunation for Birch, which starts the day after the Winter Solstice. You'll probably have to find a calendar that lists the moon phases for this to really make sense, which is a great reason to buy the Lunar Calendar: Dedicated to the Goddess in Her Many Guises!

To fully understand the tree calendar, and make it relevant to your life, you should consider yourself a student of the calendar. Study it, research it, learn about it. Most of all, make it an active part of your life. You won't understand the trees by just reading this article, or by any one thing. Look into the mysteries and myths attached to each tree. Read Robert Graves' The White Goddess and Celtic myths and fairy tales. Read all the "Lunar Energies and Esoterica," "Bach Flowers," and "Folklore and Practical Uses" columns in The Hazel Nut. Look at the rituals in Pattalee Glass-Koentop's Year of Moons, Season of Trees, (see review in #14) and write and perform a lunar ritual for yourself based on her rituals and what you've learned from Robert Graves. Make contact with a tree; meet it, talk to it, and especially, listen to it.

Each lunation, each tree, when taken separately, can teach us about ourselves, and help us get more in tune with nature's cycles. Taken as a whole, a study of the tree system can help us integrate our personalities, broaden our intellectual horizons, and open ourselves spiritually to the cosmos, going beyond the physical world. That is, after all, the point of being on the path in the first place, isn't it?

Blessed be, and happy searching!