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Search for the history of hemp in Ireland and you’ll find the same story told again and again. An ancient Celtic crop. Druids and bronze age fields. A plant woven into Irish life since before Christianity arrived.
It’s a good story. The evidence doesn’t support it.
What the evidence does support is stranger and, we’d argue, more interesting: hemp seems to have arrived in Ireland with Christian monasteries, somewhere around the eighth century. The men who first grew it here were most likely monks.
The Word That Gives It Away
Start with language, because language is unusually honest about this kind of thing.
The Irish word for hemp is cnáib. It is not an old Irish word. It is a loanword, borrowed from Clerical Latin — from canapis or canabus — and it arrived with the Church.
We can be fairly precise about when it shows up. In a 2024 review published in Cannabis and Cannabinoid Research, John McPartland and Saoirse O’Sullivan traced the word’s first appearances in Irish texts to manuscripts written in 1060 and between 1127 and 1134. Before that, nothing. The word is absent from the Old Irish glossaries, and absent from the epics and mythologies composed between roughly 600 and 900 CE.
This matters more than it might seem. Irish is a language with deep roots and a long memory. It has inherited words for the plants and animals that mattered to the people who spoke it — for oak, for apple, for salmon, for cattle. If hemp had been grown and used in Ireland for centuries before Christianity, there would almost certainly be an inherited Irish word for it.
There isn’t. And the pattern holds across the Celtic languages. As the researchers put it, words for hemp in Celtic languages are loanwords, not cognates. Every one of them was borrowed from somewhere else.
What the Bogs Remember
The second line of evidence comes from pollen.
Irish bogs and lake beds are remarkable archives. Pollen settles, gets buried, and sits there in datable layers for thousands of years. Core down through a bog and you are reading a record of what grew nearby, century by century.
In Irish cores, pollen consistent with cultivated cannabis begins appearing around 700 CE. Not before. And it appears in a telling pattern — in the vicinity of monastic sites. McPartland and O’Sullivan concluded that the onset of hemp cultivation correlated, both in time and in place, with the founding of Romano-British monasteries in Ireland.
A note on precision here, because it matters. Cannabis pollen is genuinely difficult to distinguish from hop pollen under a microscope — the two plants are closely related and their grains look much alike. Researchers use indirect methods to tell them apart, which is why the careful phrasing is “pollen consistent with cultivated cannabis” rather than “cannabis pollen.” The correlation with monasteries is a correlation, not a signed confession. It is strong evidence. It is not proof of who first put seed in Irish soil.
The Things People Actually Dug Up
Then there is the archaeology: the physical hemp, as opposed to its pollen or its name.
Hemp seeds and fibre have been recovered from Irish excavations — but from Norse-Viking and Anglo-Norman sites, which is to say from the tenth century onward. Not from Iron Age settlements. Not from the world of the Táin.
Put the three strands together and they point the same way. The word arrives with the Church. The pollen arrives around 700 CE beside monasteries. The physical remains arrive later still, in Viking and Norman towns.
Not druids. Monks.
Why Monks?
It makes practical sense once you picture it.
Early Irish monasteries were not just prayer houses. They were farms, workshops, schools and centres of administration — among the most organised economic units in the country. They had land, labour and a reason to produce their own materials rather than buy them.
Hemp is a fibre crop. It makes rope, cord, netting and coarse cloth. A monastery with boats, livestock, building projects and a scriptorium had constant use for all of those. These communities were also connected to a wider Latin-speaking European network, which is exactly how a new crop and its Latin name would travel together.
One honest caveat: we have no evidence that Irish monks used hemp as a medicine. References to hemp in Irish folk medicine are, in the words of one researcher, difficult to document. The one early medicinal mention sometimes cited — a hemp salve — comes from the Lacnunga, a tenth-century Anglo-Saxon text, not an Irish one. In Ireland, as far as the record goes, this was a fibre crop.
The Junior Partner
Hemp never became a major Irish crop, and the reason is a familiar one: flax.
Irish agriculture backed linen, and backed it hard. When the Huguenot expert Louis Crommelin published An Essay towards the Improving of the Hempen and Flaxen Manufactures in the Kingdom of Ireland in Dublin in 1705, hemp was in the title — but linen was what followed. The Irish Linen Board was established in 1711, bounties were paid, and Ulster linen went on to become world-famous. Hemp stayed in the margins.
That didn’t stop people arguing for it. Bishop George Berkeley, in The Querist in the 1730s, asked whether enterprising people might not raise hemp in the counties of Clare and Limerick — land he thought as fit for the purpose as any in the world. In 1816, Peter Besnard reported that a hemp sample grown at Bunratty, Co. Clare possessed all the qualities of the Italian.
And in 1866, a Tyrone-born physician named George Sigerson published a pamphlet in Dublin called Cannabiculture in Ireland: Its Profit and Possibility, making an economic case for hemp as an Irish crop — jobs, exports, and a reason for people to stay rather than emigrate.
One correction worth making while we’re here. You will often read that Tudor law forced Irish farmers to grow hemp. The statutes usually cited — Henry VIII’s of 1533 and Elizabeth I’s of 1563 — were English acts. We found no evidence that either was enacted for or enforced in Ireland. Irish legislation on hemp was promotional rather than compulsory: the Irish Parliament’s act of 1781, for instance, was framed as an act to promote the linen and hempen manufacture. Encouragement, not compulsion.
Where This Story Goes Next
Sigerson’s pamphlet is worth lingering on for one more reason. In it, he refers to a countryman of his who had first introduced cannabis as a medicine to Europe.
He meant William Brooke O’Shaughnessy — born in Limerick in 1809, educated in Dublin and Edinburgh, and the man who, working in Calcutta in 1838 and 1839, ran the first systematic Western clinical trials of cannabis.
And here the Irish story loops back on itself. O’Shaughnessy’s work did not stay in India. Within about five years it had reached Dublin. In 1845, Michael Donovan of the Apothecaries’ Hall published on Indian hemp in the Dublin Journal of Medical Science, opening by acknowledging his debt to O’Shaughnessy. Sir Dominic Corrigan published on it the same year. Fleetwood Churchill followed in 1849. Cases came from Robert Graves, Sir Philip Crampton and Abraham Colles — the leading names in Irish medicine at the time.
So Ireland has two distinct hemp histories, and they don’t connect in the way you’d expect. There is a fibre crop that came with the monasteries and never quite took hold. And there is a medicine that travelled from India to Dublin because a Limerick man published a paper in Calcutta.
Neither of them is Celtic.
Claims We Checked and Could Not Stand Over
While researching this, we came across several widely repeated claims about Irish hemp that we were unable to verify. In the interests of not adding to the pile:
The 850-year-old hemp cord in Dublin City Archives. The charter it hangs from is real. We found no record of the cord’s fibre ever being laboratory-tested.
Hemp growing in Limerick in 1188. This traces to a passage attributed to Gerald of Wales. We weren’t able to check the original Latin, so we can’t vouch for it.
Irish place names derived from hemp. We found no reputable source for any.
Tudor laws compelling Irish farmers to grow hemp. As above — English statutes, no evidence of Irish application.
Michael Donovan growing his own hemp. He tested tinctures made from locally available hemp and found them weak. He did not farm it.
We may be wrong about any of these, and we’d be glad to be corrected with a source.
This is a history article. It describes agricultural and medical practices of the past and is not evidence about any modern product or its effects.
Frequently Asked Questions
When did hemp arrive in Ireland?
Pollen consistent with cultivated cannabis appears in Irish cores from around 700 CE, concentrated near monastic sites. Physical remains — seeds and fibre — come from later Viking and Anglo-Norman excavations.
Did the Celts grow cannabis in Ireland?
There is no evidence that they did. The Irish word for hemp, cnáib, is borrowed from Latin and does not appear in Irish texts until the eleventh century.
Why do people say hemp is a Celtic crop?
Hemp was used by some Iron Age cultures in central Europe. The leap to pre-Christian Ireland is not supported by Irish pollen, language or archaeological evidence.
Was hemp ever a major Irish crop?
No. Flax and linen dominated. Hemp was promoted repeatedly — by Crommelin in 1705, Berkeley in the 1730s and Sigerson in 1866 — but never took hold at scale.
Were Irish farmers ever required by law to grow hemp?
We found no evidence of this. The Tudor statutes usually cited were English. Irish legislation encouraged hemp rather than compelling it.
Who was George Sigerson?
A physician, botanist, poet and later senator, born in Co. Tyrone, who published a pamphlet in 1866 arguing for hemp farming in Ireland.
What is the connection to William Brooke O’Shaughnessy?
O’Shaughnessy, born in Limerick in 1809, introduced cannabis to Western medicine through research conducted in Calcutta in 1838–39. Dublin physicians were publishing on it by 1845.
