Celtic Astrology 101

Depending on which source you believe, Celtic Astrology is either an ancient Druid form of divination based on the thirteen signs of their sacred Tree Calendar, or the comparatively recent invention of noted author Robert Graves, who first discussed the subject in his book, The White Goddess, published in 1948. Either way, the question is not whether Graves reconstituted an old system, or created a new one. What’s important is whether or not the system works. It is only through continued use and repeated empirical testing that we can actually prove an astrological method’s validity. In the meantime, if Celtic Astrology works for you, and adds something valuable to your understanding of yourself and others, it really doesn’t matter if it was founded by the ancient Druids in 500 B.C.E., or by a modern “Druid” in the 20th century.

The Druids were the priests, philosophers, educators, historians, judges, astronomers, astrologers, poets, and storytellers of the Celtic tribes that inhabited the British Isles from the second millennium B.C.E. to the first century B.C.E. The Celtic people revered and respected nature. Their priests were known as “the wise men of the trees”, and it’s said that the Druids believed that the human race was descended from trees. They envisioned the universe in the form of a tree, with roots deep in the ground and branches that reached into the heavens.

The Celtic Tree Calendar, also referred to as The Beth-Luis-Nion, consists of thirteen lunar months of twenty-eight days each, plus an intercalary day, The Nameless Day. The thirteen months and one day comprise the proverbial “year and a day” so often mentioned in legal documents, folk legends, and fairy tales.

The Druids encoded much of their knowledge in a mystical runic alphabet known as the Ogham. It is made up of simple strokes centered on or branching off a single line, each stroke corresponding to a letter of the alphabet. According to Robert Graves, the thirteen consonants of the Beth-Luis-Nion version of the Ogham alphabet correlate to the thirteen months in the Celtic calendar. Each month bears the name of a tree. Thus Beth is the birch month, Luis the rowan month, Nion the ash month, and so on. This calendar of “tree magic” was part of the religious system of the Celts, and was passed down by the Druids from generation to generation.

The word zodiac comes from the Greek zidoakos, and means “a circle of animals”. The zodiac in traditional astrology is a circle of twelve constellations that lie on or near the ecliptic (the path that the sun travels in the course of a year). People born during the days ruled by a specific zodiacal sign tend to exhibit characteristics associated with that sign.

As James Vogh points out in his revolutionary work Arachne Rising, a book that explores the possibility of a thirteen sign zodiac, “Above all astrology is a study of man in time, and time is what the zodiac (any zodiac) is meant to measure. Besides being a circle of animals, or signs, or constellations, the zodiac is a calendar.” In Celtic Astrology, the thirteen calendar months are each represented by a tree sign. People born during the days ruled by a specific tree tend to exhibit characteristics associated with that tree.

Tree Sign Chart

To determine your tree sign find your birth date in the following chart:

Birch (Beth) December 24 to January 20
Rowan (Luis) January 21 to February 17
Ash (Nion) February 18 to March 17
Alder (Fearn) March 18 to April 14
Willow (Saille) April 15 to May 12
Hawthorn (Uath) May 13 to June 9
Oak (Duir) June 10 to July 7
Holly (Tinne) July 8 to August 4
Hazel (Coll) August 5 to September 1
Vine (Muin) September 2 to September 29
Ivy (Gort) September 30 to October 27
Reed (Ngetal) October 28 to November 24
Elder (Ruis) November 25 to December 22
The Nameless Day December 23

Tree Sign Analysis


Tree Sign Dates: 24 December - 20 January
Ogham Letter: Beth
Ruling Deity: Lugh,
Druic Animal: The White Stag
Keywords: tenacious, hard-working, ambitious, loyal

To the Druids, the Birch represented renewal and rebirth because it was one of the first trees in leaf after winter. The outstanding characteristics of Birch natives are 0ambition, determination, resiliency, and the persistence to overcome setbacks. Birches are extremely loyal, and they are always ready to make sacrifices and take on responsibilities above and beyond that which their position demands. Where family is concerned the Birch individual often assumes obligations that should rightfully fall to others, even if it means that his/her own personal relationships suffer.


Tree Sign Dates: January 21- February 17
Ogham Letter: Luis
Ruling Deity: Brigid
Druic Animal: The Dragon
Keywords: far-sighted, inventive, humanitarian, eccentric

Rowan people are individualists who hate conformity and resent any authority other than their own. Their most outstanding characteristics are idealism, progressive ideas, humanitarian principles, and eccentricity. More than anything these far-sighted, imaginative folks need a mission in life, and they often dream of reaching out to help others solve their problems. The typical Rowan tends to see things from a different perspective than members of other tree signs, has an unusual imagination, and often comes up with original ideas that other people may view as odd or eccentric.


Tree Sign Dates: February 18 – March 17
Orgham Letter: Nion
Ruling Deity: Manannan mac Lir
Druic Animal: The Tern
Keywords: sensitive, spiritual, dual-natured, artistic

Deeply caring, sensitive, spiritual, psychic, dreamy, and artistic by nature, Ash people can also be pragmatic, practical, and business-like when the occasion demands it. Although neither financial success nor fame are attributes that come immediately to mind when you think of this tree sign, Ash natives have an instinct for combining their creativity with a genius for success and money making. Ashes are born healers, actors, writers, filmmakers, sailors, spiritual leaders, psychics, philanthropists, and dreamers, but they also know how to harness their talents, sensitivity, and compassion and hitch them to a rising star.


Tree Sign Dates: March 18 – April 14
Orgham Letter: Fearn
Ruling Deity: Bran
Druic Animal: The Raven
Keywords: courageous, energetic, passionate, impatient

The courageous, adventurous, impatient individuals born under this tree sign can usually be found in the forefront of any action. Naturally competitive, they need to excel. When Alders take charge, it is not because they seek power, but because they need to always be first. If you want to get an Alder native to do something, just tell him/her that it can’t be done; Alder won’t rest until your proven wrong. In business Alders often have difficulty delegating authority. Their minds are fairly bursting with fabulous ideas for new projects, but instead of asking others for help and input they try to do everything themselves.


Tree sign Dates: April 15 – May 12
Ogham Letter: Saille
Ruling Deity: Cerridwen
Druic Animal: The Serpent
Keywords: practical, resourceful, enigmatic, resilient.

The practical idealists born under this sign are strong-willed, intelligent and articulate, with powerful memories and tons of common sense. They are also intuitive, imaginative dreamers, and spiritual seekers. Although Willows generally prefer to keep controversial beliefs to themselves, at times they feel impelled to share their experience of the unknown with others. The typical Willow native is shrewd, ambitious, and sensible, but can also be quite emotional and rather mysterious. In fact Willows can be difficult people to get to know because of an enigmatic aspect to their character that generally remains hidden below the surface of the rational public persona.


Tree sign Dates: May 13 – June 9
Ogham Letter: Uath
Ruling Deity: Olwen
Druic Animal: The Owl
Keywords: communicative, mercurial, multi-talented, shrewd

Hawthorn natives are bight, innovative, creative, and confident. Gifted speakers, writers, teachers, and performers, the eloquent, charismatic people born under this tree sign are multi-talented, spontaneous, likeable, and adaptable. The Hawthorn person is mercurial and craves constant mental stimulation. Communication and study are his/her forte. These quick-witted individuals usually have a variety of interests, but a relatively short attention span that can keep them fluttering from one thing to another, without taking the time to learn any one subject in depth. They are, however, clever strategists, who know how to make a plan and stick to it when it suits their purposes.


Tree Sign Dates: June 10 – July 7
Ogham Letter: Duir
Ruling Deity: Dagda
Druic Animal: The Wren
Keywords: enthusiastic, optimistic, determined, royal

Oak is the sign of enterprise, generosity, and nobility of feeling. Individuals born under the sign of this tree are generally enthusiastic, determined and self-motivated. Natural leaders, Oaks generally seek the spotlight and are at their best in positions of power and responsibility. The typical Oak person is courageous and competitive, enjoys contests and confrontations of all types, and makes a formidable rival in business, sports, politics, or love. Proud yet gracious in victory, Oaks are magnanimous in defeat. Although they have the willpower to overcome most obstacles and setbacks, their ability to succeed is tempered by a high moral code and sense of fair play.


Tree Sign Dates: July 8 to August 4
Ogham Letter: Tinne
Ruling Deity: Danu
Druic Animal: The Unicorn
Keywords: trustworthy, capable, generous, compassionate

People born under the tree sign Holly have artistic temperaments and powerful, vivid imaginations. Considering Holly’s innate sensitivity and creativity, it is small wonder that this sign has produced some of our best writers, actors, painters, filmmakers, and musicians. Holly’s creativity is rooted in common sense and sound business principles that allows them to manage and promote themselves, and their creations, in a way that assures success in the real world. Whether he/she works in an artistic, professional, or business medium, at heart the imaginative Holly individual is a realist, with his/her feet planted solidly on the ground.


Tree Sign Dates: August 5 – September 1
Ogham Letter: Coll
Ruling Deity: Fionn mac Cumhaill
Druic Animal: The Salmon
Keywords: intelligent, strong-willed, perceptive, idealistic

Hazel is sometimes referred to as, “the tree that wants to be first”, because on the European continent it is the first to flower in the spring; those born under its influence also want to be first. Although strong and resolute on the inside, they hide their determination under a ton of charm and charisma. Generally gifted with artistic and creative ability and a decided flair for the dramatic, they have the personal potential to succeed where others might fail because they have the will power to finish whatever they start. Basically loyal, noble, and trustworthy, those born under the tree sign Hazel don’t like having their honesty questioned or their dignity undermined.


Tree Sign Dates: September 2 – September 29
Ogham Letter: Muin
Ruling Deity: Etain
Druic Animal: The Swan
Keywords: methodical, analytical, sensitive, compassionate

Individuals born under Vine’s influence tend to be more serious in outlook and modest in demeanor than natives of summer’s Oak, Holly, and Hazel. Vine people invariably strive to “do the right thing”, but sometimes they come off as overly critical idealists, more interested in organizing and analyzing life than living it. Because of their need to be of help and service to others, Vines often take on extra responsibility for their family and friends; they feel impelled to try and “fix” whatever is wrong in other people’s lives. In personal relationships Vines set extremely high standards. Although outwardly cool and seemingly unemotional, beneath the façade the vine type is sensitive and much more vulnerable than he/she appears.


Ogham Letter: Gort
Tree Sign Dates: September 30 – October 27
Ruling Deity: Arianrhod
Druic Animal: The Butterfly
Keywords: artistic, sociable, romantic, conciliatory

Ivy natives are among the most civilized of all the tree signs, and the epitome of elegance, charm, and good taste. These lovers of beauty and harmony are romantic and sociable by nature, and they don’t like being alone. Although Ivies crave partnership, they tend to love more with their heads, than their hearts. Those born under this tree sign are idealistic and they refuse to be emotionally compromised. They would rather let go of a relationship, than continue under less than ideal circumstances. However, should his/her partner decide that the relationship is over when Ivy is not ready to end it, he/she can become as possessive and clingy as the plant that rules this sign.


Ogham Letter: Ngetal
Tree Sign Dates: October 28 – November 24
Ruling Deity: Pwyll
Druic Animal: The Hound
Keywords: complex, mysterious, forceful, uncompromising

Reed individuals are born survivors with a strong sense of purpose and the independence of spirit essential to overcoming impossible odds. No other tree sign is blessed (or cursed) with their indomitable character and ability to take charge and control a situation. Their great inner strength and uncompromising tenacity makes it possible for Reeds to focus totally on a chosen task until their objective has been reached. Their judgment is shrewd and accurate, and their phenomenal memories can be of great help in their work, but also causes them to brood and jealously hang onto emotional wounds and slights. Those born under Reed have an innate belief in their own destiny and capacity to play an important part in transforming the world around them.


Ogham Letter: Ruis
Tree Sign Dates: November 25 – December 22
Ruling Deity: Pryderi
Druic Animal: The White Horse
Keywords: independent, adventurous, philosophical, outspoken

The Elder individual is optimistic, enthusiastic, and eager to expand his horizons and experience everything that life has to offer. Typically Elder believes that variety is the spice of life, and is always on the lookout for new challenges and adventures. Elder’s adaptable nature allows him/her to bend according to the situation and company. However, their restless temperament makes them dislike tedious schedules and repetitive routine, and they will generally resist any attempt to box them in or pressure them into doing things they don’t want to do. Although at times Elder may appear somewhat shallow or superficial, he/she is actually deeply philosophical. Elder’s tendency to move from experience to experience is part of an ongoing search for a higher truth.

The Nameless Day

Date: December 23
Plant Association: Mistletoe
Keywords: dedicated, responsible, persistent, devoted

The “missing day” in the Celtic Tree Calendar is the intercalary day, December 23. Although The Nameless Day has no Ogham symbol, and is not ruled by any tree, the Druids associated it with the mythology of the Mistletoe. Individuals born on the Nameless Day seem to function best when forced to deal with setbacks and adversity. Motivated by ambition and the desire to succeed, Nameless Day people absolutely refuse to give up on anything they consider important, and their natural aptitude for combining hard work with steely determination helps them attain their objectives. Although often tormented by fear of failure, those born on the Nameless Day somehow manage to overcome their insecurities and hang on until their goals have been reached.

Phyllis Vega is the author of Celtic Astrology: How the Mystical Power of the Druid Tree Signs Can Transform Your Life, New Page Books (July 2002). This article was originally published in Sydney Omarr’s Astrological Guide for You in 2005, Copyright 2004 © Phyllis Vega, The Estate of Sydney Omarr, and Writer’s House LLC. All Rights Reserved.