Reconstructing the substance gruit: an experiment

As part of the Experimental Archaeology Conference EAC12 hosted by EXARC this spring, I ran a handful of gruit experiments. Many gruit-beer experiments concern themselves with flavor and herbal components. They do not consider how or why the gruit substance may contribute to a longer shelf life, nor the reason its reputation as an essential element in brewing persisted for centuries even after hops came into common use. The consistent occurrence of grain in the surviving medieval tax records indicates that the grain aspect of the malt could be considerably more important than previously thought.

My experiments examine how the gruit substance affects fermentation and alcohol content, and therefore shelf life, leading to greater economic possibilities. In this blog post I will show you behind the scenes, so to speak, and share with you a bit more context and explanation than I was able to squeeze into my 5-minute video poster presentation. The experiments do not discuss gruit in the modern obsession of brewing with whatever herb one can get their hands on; to capture the essence of terroir, preferably in defiance of the hops establishment. While being much fun in its own right, it is not a very historic practice. My interest is in the medieval product itself: the substance of gruit and its herbal additives, and how this relates to the increased economics of the produced beer.

Contrary to what many modern publications would like us to believe, the historical sources are quite persistent that gruit is something more than just a collection of regionally unique herbs. A closer look at the etymology of the word gruit indicates an intimate connection with malt, in the form of coarsely ground grain. Even with variable medieval spelling, the different variants of the word are consistent with each other, and mean either the substance gruit, the beer brewed with it, coarsely ground grain, and the porridge made with such. Several Latin deeds use the words frumentum and polenta to describe the substance gruit, both words indicating a grain product. (Doorman 1955, 72; Ebbing 1994, 26-27; Kieft 1964, 165; Verberg 2018, 69)

If Low Country gruit indeed consisted of a concentrated malt porridge fortified with preserving botanicals and possibly yeast-rich chaff, then this would also explain several other Latin terms associated with the gruit product. When concentrated malt is added to the wort at the time of pitching, the boost of fermentable sugars would significantly enhance yeast fermentation. This would result in visible fermentation signs, giving the impression the gruit caused the “ferment” to happen. This effect resulted in the term levarentur for gruit, which is the Latin for leaven, or rising, and is also used for leavened or risen bread. As the concentrated paste caramelizes during the cooking down, adding this concentrate could darken the color of the wort as well, as suggested with the term pigmentum. The increase in fermentable sugars would raise the alcohol by volume, which combined with the preserving herbs and postponed spoilage just long enough for local commerce to be possible.

Two of the term definitions — gruit from the Low Countries, and grout from the British Isles — are connected to brewing. In the case of Low Country gruit, its connection with herbal ingredients is undisputed, while its connection with malted grain is questioned. In the case of British grout, a partially fermented cooked malt extract used to strengthen wort, interestingly, its connection with malted grain is undisputed – it is a known yeast-malt concentrate. It is not clear whether herbs played a role in medieval production, but they are not mentioned in early-modern grout descriptions. (Dodoaeus 1644, 813; Karkeek 1877, 196-97; Verberg 2018, 52)

If the substance of gruit indeed consisted of two parts – something produced with malt and heating equipment, and a combination of preservative botanicals – then it would stand to reason the malt portion is comparable to the malt product of British grout. And while there are no medieval recipes or process descriptions for medieval gruit, we are lucky with a couple post-period instructions for a similar product with a shared background.

I had located three publications which shared recipes on how to make grout. (Know of any others? Please share!) The 17th century publication quotes the 16th century source, and all three are about British grout. This is not unexpected, as by the 16th century, although in some areas the taxation is still active, the production and sale of the gruit substance had just about died out without a trace.

The first to publish a recipe for grout is the Dutch botanist Matthias l’Obel, also known as Lobelius, in his herbal Kruydtboeck oft beschrijvinghe van allerleye ghewassen, kruyderen, hesteren ende gheboomten First published in 1551, the edition that is freely available today, and from which I quote, is from 1581.

Graut wordt aldus ghemaeckt. Neemt ses of acht ponden ghemalen Mouts / siende heet water xij. oft xv. pont / de welcke tsaemen gheroert en wel onder een ghemengt zijnde ses mael sdaeghs / en met cleedere en stroo zeer we ghedeckt zijnde soo langhe tsaemen in een schoon vat sal staen weycken tot dat soo dicke wordt als een syroop. Daer nae salt voorts metten viere opghesoden worden / alleneen zeer neerstich roerende op dat niet aen en berne / tot dat soo dicke als pap gheworden is.” Graut is made thus. Take six or eight pounds of ground malt / seething hot water 12 to 15 pounds / the which is stirred together and is well mixed six times a day / and with cloths and straw well covered, shall soak so long in a barrel until it becomes thick as syrup. After that shall it quickly be heated with fire/ only stir very well as that it does not burn / until it is as thick as porridge.

L’Obel 1581

This recipe is reiterated by another Dutch herbalist, Rembert Dodoens (latinized as Rembertus Dodonaeus) in his herbal Herbarius oft Cruydt-Boeck. The 1554 edition titled the Cruijdeboeckonly lists botanical detail, which in the 1644 edition is updated and expanded upon to include product history as well as the occasional practical recipes.

Graut of Naerbier wordt aldus ghemaeckt / seyde Lobel: Neemt sex of acht ponden gemalen Mouts / twaelf oft vijftien ponded siedende heet water: Roert dit tsamen wel onder een / zes mael daegs: Decket seer well met cleederen ende stroo: ende laetet tsamen soo lange in een schoon vat staen weycken tot dattet soo dick wort als eenen Stroop. Daer nae suldij dat voorts metten viere opsieden / alleen seer naerstich roerende / op dat niet aen een berne / to dattet soo dick als pap geworden is.” Graut or Naerbier is made thus / said Lobel: Take six or eight pounds of ground malt / twelve or fifteen pounds seething hot water: Mix this together well / six times a day: Cover it very well with cloths and straw: and let it soak together for so long in a clean barrel that is becomes as thick as a syrup. After that cook it up again with fire / only stir very well / as that it does not burn / until it becomes as thick as porridge.

Dodonaeus 1644, page 813

A much later version, associated with the infamous White Ale, is published by Samuel Gray in The Operative Chemist (1828):

“Pale ale wort 25 gall, hops 2 handfuls, yeast 3lb, grouts 6 or 8lb. When the fermentation is at its height, bottle in strong stone half pints, well corked and wired; it effervesces when opened. The grouts here mentioned are made by infusing 6 or 8lb of malt in a gallon and a half of water, covering it warm by the fire side, stirring it often: when in full fermentation it is to be boiled down to a thick paste.”

Gray 1828

The etymology of the British word grout is very similar to that for continental gruit, and points back to the shared Latin term grut. It is entirely possible British grout and Low Country gruit shared common ancestry, but evolved separately. But how likely it would be for the two products, used in a similar way, to deviate so much, so quickly, is debatable. It is more likely the two shared more than their names, their use as additive in brewing, their reputation of a potent ferment – they probably also shared their base ingredient: the grain. Dutch historian Irsigler came to a similar conclusion: “What is certain is that a porridge was prepared from the various basic ingredients, especially from bog myrtle, ground malt, laurel berries and laserwort, which was heated, and then dried again.” (Alberts 2017, 52; Dodoaeus 1644, 813; Ebbing 1994, 29-30; Hornsey 2003, 530; Irsigler 1973, 84; Verberg 2018, 58-59)

With this in mind, I choose to run a small experiment and brew three interpretations of gruit to test several variables:

  • Could the gruit paste and gruit porridge, as instructed by the post-period recipes, adequately emulate the medieval gruit substance descriptions?
  • Does the addition of this gruit paste or porridge significantly change the specific gravity (SG) of the wort and thus the resulting alcohol by volume (ABV)?
  • Does gruit-porridge & syrup wort sour less quickly than the herbed, and/or plain wort?

For this I needed four samples:

  • Sample 1: plain wort
  • Sample 2: wort, plus the herbal & resin additive
  • Sample 3: wort, plus a malt syrup with the herbal & resin additives
  • Sample 4: wort, plus a grain-in malt porridge, with the herbal & resin additives

The wort was made by diluting a can of brewing malt extract to a SG of 1.05 (as advised for the brewing of standard 5% beer) and dividing the resulting wort over 4 one-gallon glass carboys.

I used a bread yeast as the more period-appropriate kveik starter was delayed in activation (our wood heated house might be too cold for its liking).

Producing the gruit substance

Version one:
Taking inspiration from the above-mentioned recipes, in specific the one by Lobelius (1554), I devised the following process for the first trial gruit: the porridge.

Process: Add 8 lbs of ground malt and 1.5 gallon of boiling water to my copper brewing kettle. Cover well, stir often, for a day. The next day, place on wood fired stove and slowly cook down to a thick porridge. Stir well to prevent burning.

Result: This indeed produces a sticky, dry porridge. It caramelizes well but is difficult not to burn at the bottom. It is easy to incorporate the crushed dry herbs and heated resin.

Version two:
As none of the recipes indicate whether the mash would be lautered (the liquid wort is filtered off the spent grains) and the wording is ambiguous (is it a syrup, or a porridge), I opted to make two versions, a grain-in and a filtered extract. The recipe for the porridge version did not generate much liquid, so for the syrup version I slightly tweaked the liquid volume to make sure there would be enough volume to concentrate (as the instructions do not suggest to sparge). The additives added later were adjusted accordingly.

Process: Add 6 lbs of ground malt (contained within a brew-bag) and 15 lbs (nearly 1.5 gallon) boiling water to the copper brewing kettle. Cover well, stir often, for a day. The next day, remove the brew-bag and thereby the grains (in lieu of a lauter tun). Place the kettle and the drained wort on the wood fired stove, and slowly cook this down to the consistency of syrup.

Result: This process produced a beautiful thick caramelized syrup. The evaporation did not require a lot of attention (unlike version one) and anyone with experience making jams and maple syrup will have no trouble recreating this. Be aware that hot syrup is more liquid than syrup at room temperature, without experience one could be tempted to overcook and burn.

The herbal additives

As suggested by the medieval gruithuis purchase accounts, I used the following herbs in the herbal mixture:

  • Bog myrtle; leaves and catkins
  • Laurel berries
  • Caraway (substituted for the unavailable laserwort)
  • Pine resin (colophon)

There are nearly no records available for the specific amounts of these herbs and spices in the gruit mixture. The one post-period recipe for Gruytbier uses very small amounts of herbs, and no malt (it does mention chaff; a gruit grain alternative, and something for another experiment).

“Om Gruyt, ende Gruytbier te maken. Neemt tegen eenen pot een koren bakelaer, ende alsoo veel aipoys, ende wat haveren doppen, ende twee saykens van gagel. Ende maeckt dit bier alleen van gherstenmoute, ende set dit dan met ghiste.” To make gruit and gruit beer. Take against one pot (half a gallon) a laurel berry, and also much resin, and some oat bran, and two seeds of bog myrtle. And make this beer only of barley malt, and set it with yeast.

The gruithuis accounts seem to indicate bog myrtle to be used most, and that laserwort was the most expensive ingredient. Modern science found that 2 grams per liter would inhibit lactobacillus souring (introduced 20 minutes before flame-out). Bog myrtle can have an overpowering flavor. The amount of herbs is adjusted according to the amount of malt used for the base gruit.

Gruit 1 (porridge) adjuncts: 30 grams of bog myrtle (20 gr leaves and 10 gr catkins), 30 gr of laurel berries and 5 gr of caraway seeds; as well as 42.5 gr (1.5 oz) of distilled pine resin. The herbs were crushed using a mortar and pestle.

Gruit 2 (paste) adjuncts: 22.5 gr of bog myrtle (15/7.5), 22.5 gr of laurel berries and 3.75 gr of caraway; 42.5 gr (1.5 oz) of distilled pine resin. The herbs were crushed using a mortar and pestle.

The four fermentation vessels are started as follows:

  • Wort 1 (porridge) includes a half gallon of plain wort, fortified with 9 ounces of gruit porridge.
  • Wort 2 (paste) includes a half gallon of plain wort, fortified with 4.25 ounces of gruit paste.
  • Wort 3 (herbed) was fortified with 3.75 gr of bog myrtle (2.5/1.25), 3.75 gr of laurel berries, and 0.6 gr of caraway seeds; 5 gr (? oz) of distilled pine resin. The herbs were crushed using a mortar and pestle.
  • Wort 4 (plain tester) is not fortified.

The carboys are capped with airlocks filled with star-san which will create bubbles to indicate active fermentation. They are then placed on a heating mat and wrapped with a blanket as the ideal fermentation temperature for bread yeast is 70-80 F (21-27 C).

At regular intervals, the specific gravity (SG) of the wort was tested. The addition of the gruit paste and porridge significantly raised the amounts of sugars in solution, raising the specific gravity and thus the alcohol by volume (ABV). The addition of extra sugars to a grain wort is also found in Farmhouse brewing, and is thought to have originated with the brewing with oats instead of barley. Oats do not saccharify as efficiently as barley and wheat, and to still make a strong beer, the Farmhouse brewers would add extra sugars. Oats are easier to grow, and in much of the Low Countries oats were the norm.

The table below indicates the starting or original gravity of the four different wort samples, as well as the final gravity reading at three weeks. The alcohol by volume is calculated as follows: (FG – OG) x 131.25 = ABV % The readings of the herbed and plain samples are identical, as expected, while the porridge levels are slightly higher than the paste. This is likely due to the spent grains not being sparged, or rinsed.

      Original Gravity               Final Gravity              ABV %
Porridge                      1.068                           1.024               5.775%
Paste                            1.062                           1.026               4.725%
Herbed                        1.052                           1.020               4.2%
Plain                            1.052                           1.020               4.2%

The readings of this proof-of-concept experiment indicates that, yes, adding gruit paste makes for a stronger beer. This supports the theory that the gruit substance positively affects fermentation including alcohol content and thus shelf life, leading to greater economic possibilities.

Question: If the shelf life of the brew is extended, either through raising the ABV % or by adding preservative herbs, can this be tasted in the resulting brew? How fast do the different samples sour?

  • Day 1: Pitched the yeast.
  • Day 6: all samples are effervescent, and sweet.
  • Day 12: The plain sample went sour (badly).
  • Day 16: The herbed sample is going (nicely) sour.
  • Day 20: The two gruit paste/resinated samples are still going strong, but unclear if this is due to the increased ABV or the potent resin.

Question: Can chaff (grain hulls) function as a source of spontaneous fermentation?

My experiment was not able to answer this specific question at this time as the local mill used to source fresh chaff in the past was closed to walk-ins due to the pandemic. But: the significant difference in the ABV % between the porridge (which includes the naturally yeasty chaff) and syrup might indicate there is validity to this: instead of providing active yeast, perhaps the chaff provides yeast nutrients and promotes vigorous fermentation. Happy yeast results in a quicker and potentially higher sugar to alcohol conversion. English grout uses dead yeast for a similar purpose.

Unanticipated Question: Does resin alone have a noticeable preservative effect, does the manner how it is added to the gruit paste matter?

The gruit syrup had a slightly higher amount of resin than the porridge due to oversight (did not account for the 2lbs difference between the two). The syrup brew stopped showing signs of active fermentation (bubbles) within a few days, unlike the other two, and it also tasted much more resiny (an unpleasant, antiseptic, mouth numbing taste). The heated liquid resin was poured into all three samples, but unlike my previous brewing with resin experiences where it was added to room temperature wort, it now was added to hot porridge and syrup as well. Presumably, the resin dissolved much more completely, dispersed much more finely, which significantly enhanced its preservative effect, as well as its unusual flavor. The resin flavor, while initially very sharp, did mellow out over time (now, two months later, it still has not soured and while it does not drink well, it does work great as a cooking beer).

The addition of herbs to plain wort somewhat slowed down the souring process. The addition of grain paste to raise the SG slowed down souring even more, and the use of resin boosts this protection further. Concentrating gruit porridge takes more effort to prevent burning than concentrating into syrup, but unexpectedly, the benefits of a higher OG (no wort lost by removing the spent grains) and possible yeast nutrients could make up for this inconvenience. The addition of resin might be more important in connection to the preservative function of gruit than previously assumed.

Food Drinks for thought…
That the ABV percentage would be higher after adding concentrated malt (gruit paste) was assumed, but the difference is more significant than initially expected. Porridge gruit could be a viable option: syrup seemed to be the obvious choice but the experiment seems to indicate porridge to be more efficient. The difference in application between adding hot resin to cold substrate as opposed to adding hot resin to hot substrate is significant. The unexpected effect seems reminiscent of my wax comb mead experiments, where the hot wax dispersed into the wort but did not re-solidify when cooled, and further investigation is warranted.

Poster presentation at the Experimental Archaeology Conference #EAC12, Wednesday March 31st, Session 12. After the presentations follows a one-hour live session with Questions & Answers. Please Join us.

Overview of Session 12:


  • Alberts, Leen. 2017. Brouwen aan de Eem: Amersfoort, een Stichtse bierstad in de late middeleeuwen. Hilversum: Uitgeverij Verloren.
  • Arnold, John P. 1911. Origin and History of Beer and Brewing. Reprint Edition 2005. Cleveland, Ohio: Beer Books.
  • Dodonaeus, Rembertus (Rembert Doedesz Joenckema). 1644. Herbarius oft Cruydt-Boeck. Leiden: Inde Plantijnsche Druckerije van Francoys van Ravelingen. Plantaardigheden.
  • Doorman, G. 1955. De Middeleeuwse Brouwerij en de Gruit. (The Mediaeval Brewery and the Gruit). Den Haag: Martinus Nijhoff.
  • Ebbing, Hans. 1994. Gruytgeld ende Hoppenbier. Een onderzoek naar de samenstelling van de gruit en de opkomst van de Hollandse bierbrouwerij van circa 1000-1500. Doctoraalscriptie middeleeuwse geschiedenis. Amsterdam: Universiteit van Amsterdam.
  • Gray, Samuel Frederick. 1828.  The Operative Chemist. London: Hurst, Chance, and Co.
  • Hasselt, Gerard van. 1804. Arnhemsche oudheden, Volume 2. Arnhem: J. H. Moeleman Junior.
  • Hornsey, Ian Spencer. 2003. A History of Beer and Brewing. RSC Paperbacks. Cambridge: Royal Society of Chemistry.
  • Irsigler, Franz. 1973. “Hermann von Goch als Kölner Grutpächter.” In Aus Geschichte und Volkskunde von Stadt und Raum Bonn: Festschrift Josef Dietz zum 80. Geburtstag am 8. April 1973, ed. Edith Ennen and Dietrich Höroldt, 79-88. Bonn: Röhrscheid.
  • Karkeek, Paul Q. 1877. “White Ale.” Reports and Transactions of the Devonshire Association for the Advancement of Science, Literature and Art 9:188-197.
  • Kieft, C. van de. 1964. “Gruit en ban.” Tijdschrift voor de geschiedenis 77: 158-168.
  • Matthias Lobelius (l’Obel). Kruydtboeck oft beschrijvinghe van allerleye ghewassen, kruyderen, hesteren ende gheboomten. Christoffel Plantijn, 1581.
  • Schiller, Karl & Lübben, August. 1876. Mittelniederdeutsches Wörterbuch. Zweiter Band G-L. Bremen: Kühtmann’s Buchhandlung.
  • Runde, Justus F. 1788. Aus führliche Darstellung der gerechten Ansprüche des Grafen zu Bentheim Tecklenburg auf die Herrschaft Bedbur, gegen den Grafen von SalmReiferscheid.
  • Verberg, Susan. 2018. “The Rise and Fall of Gruit.” Brewery History Journal. 174: 46-78. ResearchGate.


Gruit contains bog myrtle, marsh rosemary – and yarrow?

One of the better-known historic beers, gruit beer might just as well be also the one most misunderstood. The importance of gruit beer within the socio-economic and political structure of medieval Europe meant much is written about the taxation system surrounding gruit. But the product gruit did not receive much attention, at least not until very recent times (see my publication “The Rise and Fall of Gruit”). Gruit beer is enjoying a resurgence as an alternative to hopped beers. This craft beer revival has many brewers taking a closer look at recreating historic beers, including gruit beer. What they will find is the idea that the identity of Low Country gruit is unclear and unlikely to ever be solved. But that the best guess is that the herbs used were bog myrtle, marsh rosemary – and yarrow. And no matter how hard I look, I cannot find an “historical link” between gruit and yarrow.

To be clear, this story is about historic gruit beer, not modern gruit ale which can use any type of botanical additive as long as it is not hops. Historic gruit beer is much more narrowly defined, mostly using the same three kinds of herbs, pine resin and a grain product. There are many websites discussing modern gruit ale, but only a few talk about historic gruit beer. Alexandre Bessette of says the following on the historic gruit beer ingredients:

Bessette: “Gruit ale is historically linked with these 3 herbs. Delicious and satisfying beers can be brewed from either of these on their own, but a true gruit will usually contains all three.”

The three main herbs used in historic gruit beer are bog myrtle or marsh rosemary, laurel berries and laserwort. The data from nine different gruit brewing city accounts show these purchases consistently and without much variation. But those are not the three herbs Bessette referred to: he meant bog myrtle, as well as marsh rosemary – and yarrow. Bessette is mentioned by Richard Unger in his article “Gruit and the preservation of beer in the Middle Ages” and he said about Bessette’s work on reviving the interest in a drink made with that combination that:

Unger: “… he is performing a valuable service in creating a range of experiments which set out to create something like the medieval drink. His own experience harvesting bog myrtle, yarrow and marsh rosemary in eastern Quebec to create a marketable gruit have yielded information about the process of creating what he and many others conclude is the additive. His posting of various recipes ad requests for reports on what brewers found when they have made various forms of herbal beer has already expanded the range of experimental archaeology.”

Kevin Cullen, an experimental archaeologist from the Discovery World in Milwaukee, Wisconsin, was involved in a similar brewing experiment as part of the “Ale Through the Ages” brewing seminar hosted in 2011. Cullen brewed a Belgian Gruit Ale based on the same three botanicals as Bessette mentioned, as well as juniper.

Cullen: “The three most common herbs were Bog Myrtle (Miricia gale), Yarrow (Achillea milleflolium) and Wild Rosemary (Ledum palustr).  Other later gruit additions often included: Cardamom, Caraway, Ginger, etc. Therefore, this all-grain recipe is true to the pre-14th Century Belgian Gruit style, which combined bog myrtle, yarrow, wild rosemary and juniper berries.”

The mention of pre-14th century by Cullen reminded me of a collection of supposed historic beer recipes published in “Old British Beers Book” by beer historian John Harrison, member of the Durden Park Beer Circle which he may or may not have been aware of. It lists two “Gruit Ale (ca. 1300)” recipes which, to the common brewer, seem to suggest they are based on an actual historical recipe. Both recipes again advise using bog myrtle, marsh rosemary and yarrow. They reference to Jeffrey Patton’s “Additives in Beer: Adulterants and Contaminants.” As Patton does not list any recipes, presumably Harrison’s recipes are his best guesses based on Patton’s information, not on any literal recipe (and this makes sense, as the grain bill is modern). Patton, again, reiterates the same three botanicals.

Patton: “The three major ingredients of gruit were:
1. Myrica gale, also known as sweet gale, pors, porze or porst.
2. Ledum palustre, also known as marsh or wild rosemary.
3. Achillea millefolium, also known as milfoil or yarrow.”

He does not cite his information but his bibliography shows he is familiar with Corran (1975) and Arnold (1911). He goes on to say the composition did vary from region to region and refers to the 1393 Cologne accounts, which list similar alternative herbal ingredients as Cullen mentioned. This is correct, but only partially, as from all the city accounts that survived the years, only the Cologne accounts suggests botanical variety.

But first, let’s take a closer look at the botanicals. Why these three? The first two, bog myrtle and marsh rosemary are easy. They are both found in the city accounts although there is a bit of a trick as both marsh rosemary and bog myrtle are known as pors. The properties and function of the two plants is so similar that they could be used interchangeably. It seems that the gruit producers bought bog myrtle and marsh rosemary at trade markets but that the two were not traded long-distance. Bog myrtle and marsh rosemary grow in mostly separate habitats with marsh rosemary more northern (circumpolar). This means the Belgium and Dutch regions of the Low Countries would use native bog myrtle, and the northern German region would use native marsh rosemary. Both bog myrtle and marsh rosemary were gruit ingredients, but not as two separate ingredients used in combination, in the way modern brewers envision.

The third ingredient, yarrow, is a bit of a mystery. So, what about the cardamom, caraway, ginger and juniper berries as mentioned by Cullen? The connection with cardamom is a bit unclear, but caraway, ginger and juniper come from the 1391/93 city accounts from Cologne, Germany. The accounts list the purchases of caraway, cumin, anise and juniper, as well as the actually common gruit ingredient laurel berries and bog myrtle of course (ginger is a likely mistranslation of juniper). What they also list are two ingredients they apparently wanted, but did not have: the laserwort and resin.

Laserwort is part of the plant family Apiaceae, as are caraway, cumin and anise, and juniper could potentially stand in for the missing resin. It looks like the gruit producer in Cologne was trying his best to emulate the product of his peers. Even though he used different ingredients, apparently he wanted his product to fit in, not stand out. He was not alone in this sentiment. By 1408, the gruit from Neuss was thought to be “much better than that from Cologne.” So… how “gruit” are these ingredients? If the brewer preferred the standard bunch, and the locals preferred the gruit from somewhere else, then my guess is not so much.

backyard yarrow

Then again, what about the yarrow? I am not sure. Out of the city accounts of nine Dutch and German cities spanning from 1339 to 1530, not a single one mentions yarrow. The accounts do consistently mention bog myrtle, marsh rosemary (but only for Munster and Wesel), laurel berries, laserwort, resin and some sort of grain product, in the form of malt, flour or chaff. If the information in the city accounts does not match the description of gruit found in popular publications, are modern publications consistently reprinting misinformation?

According to Ann Hagen in her expansive tome “Anglo-Saxon Food and Drink” (1992/2010), yarrow is found in connection with Anglo-Saxon English brewing. Odd Nordland in his well-researched “Brewing and Beer Traditions in Norway” (1969) found that yarrow, although not as often as bog myrtle by far, was part of Nordic historic brewing. But as gruit was only brewed in the Low Countries, which covered what is now the Netherlands, Belgium, northern France and western Germany, this does not mean yarrow therefore was part of gruit. The assumption that the growing range of bog myrtle was synonymous with the production of gruit and gruit beer by for instance Richard Unger would explain why these sources are absorbed into the history of gruit. Or perhaps modern researchers also had trouble connecting yarrow with gruit, and went with the assumption that if neighboring countries would use it, then surely the Low Countries would too?

The Scandinavian author Nils von Hofsten, who wrote extensively on the use of herbs in Scandinavian brewing, believes the use of yarrow in gruit “is very questionable.” Mika Laitinen voices a similar sentiment in his “Viking Age Brew: The Craft of Brewing Sahti Farmhouse Ale”

Laitinen: “Many sources claim that yarrow (Achillea millefolium) was a typical constituent of gruit, but that is perhaps a misconception. I think the claim is rooted in another misconception, that the gruit region extended to the Nordic area.”

Tracking gruit – and in its wake, yarrow – through many publications I noticed an interesting pattern: the same books would show up in the bibliographies, books which perpetuated the connection of gruit and yarrow. Unfortunately, many of these books do not cite their sources (well) and several are dead ends. Hagen (2010) for instance referenced “A History of Brewing” by Corran (1975) but Corran does not cite his source.

Corran: “Before hopped beer became customary in German, a mixture of herbs, including bog myrtle, rosemary and yarrow, among others, was employed; this mixture was known as gruit, and the product as gruit beer.”

A bit more round-about, Harrison (1993) referenced Patton (1989) which has no references but does have a bibliography. Patton is familiar with both Corran and the “Origin and History of Beer and Brewing” by Arnold (1911) but unfortunately both Corran and Arnold are dead ends.

Arnold: “Opinions as to what went into the composition of gruit differed formerly, and even to-day, somewhat. However, to judge from the scan information that has come down to us at this point, it must have been chiefly three plants which formed the stock of the gruit, namely:

1. Myrica Gale, sweet gale, called in Westphalia Pors, Porze, Porst, and the same in Danish, as well as Swedish; well-known also in the moors and bogs of Scotland and elsewhere.
2. Ledum Palustre, marsh or wild rosemary, in German Sumpfporst, porst, wilder Rosmarin, Bienen-, Brauerkraut, also Wanzen- or Mottenkraut (moth or bug herb).
3. Achillea Millefolium, milfoil, yarrow; German Schafgarbe.”

Unger (2011) references “The Mediaeval Brewery and the gruit” by Doorman (1955), among others, and even though Doorman worked from primary sources and lists the correct herbal ingredients of bog myrtle, marsh rosemary, laurel berries, laserwort and resin., he also added yarrow. But without citation this is another dead-end. Doorman did list “Beer has a History” by Frank King (1947) in his bibliography, which might explain why he felt the need to add yarrow even though his historical sources do not support it.

King: “Gruit was a mixture of herbs which included sweet gall or bog-myrtle, marsh or wild rosemary, and yarrow or milfoil and probably other ingredients.”

Unger also cites “A History of Beer and Brewing” by Hornsey (2003), who in turn (probably) cites the dead-end Corran (1975). Before it gets too confusing, let’s put the most influential authors in order of publishing: Unger (2011), followed by Hornsey (2009), Buhner (1998), Hagen (1992), Harrison (1993), Corran (1975), Doorman (1955), King (1947) and finally Arnold (1911). It seems that most of the English language popular publications refer back to either Corran or Arnold. Neither Corran nor Arnold left any hint of where they themselves came across the information.

Without having anything more to go on, for now, Arnold (1911) is as far back I’ve been able to track the use of yarrow in Low Country gruit. I had high hopes for John Bickerdyke’s “The Curiosities of Ale & Beer: An Entertaining History” (1889) but it does not mention gruit (or yarrow) at all. Perhaps the gruit/yarrow connection originated in a non-English source? It is a non-English drink, so that would make sense. Either way, I am rather impressed by how solidly this one ingredient attached itself to the history of gruit and will definitely keep an eye out for any new leads. Whomever first wrote down the idea must have presented it with gusto for it to have become such a solid fact.

My question to you, the reader: do you have any old and obscure brewing books on your physical or virtual book shelves? Can you take a look and see what is to be found in there? I just know Arnold is citing from another source, and wouldn’t it be cool if together we could find out from where. Proost!


  • Arnold, John P. 1911. Origin and History of Beer and Brewing. Reprint Edition 2005. Cleveland, Ohio: Beer Books.
  • Bessette, Alexandre.
  • Buhner, Stephen Harrod. 1998. Sacred Herbal and Healing Beers. Boulder, Colorado: Brewers Publications.
  • Corran, H. S. 1975. A history of brewing. David and Charles.
  • Cullen, Kevin.
  • Doorman, G. 1955. De Middeleeuwse Brouwerij en de Gruit. (The Mediaeval Brewery and the gruit). Den Haag: Martinus Nijhoff.
  • Hagen, Ann. 2010. Anglo-Saxon Food and Drink. Combined version of: A handbook of Anglo-Saxon food: processing and consumption, published in 1992, and A second handbook of Anglo-Saxon food & drink: production & distribution, published in 1995. Hockwold cum Wilton, Norfolk, England: Anglo-Saxon Books.
  • Harrison, John. 1993. Old British Beers and How to Make Them. Durden Park Beer Circle.
  • Hofsten, Nils von. 1960. Pors och andra Humleersättningar och ölkryddor i äldre tider (Bog Myrtle (Myrica gale) and Other Substitutes for Hops in Former Times). Acta Academie Regie Gustavi Adolphi Vol. 36. Copenhaven: Lundequistska Bokhandeln.
  • Hornsey, Ian Spencer. 2003. A History of Beer and Brewing. Royal Society of Chemistry. Cambridge, UK: RSC Paperbacks. Academia.
  • Laitinen, Mika. 2019. Viking Age Brew: The Craft of Brewing Sahti Farmhouse Ale. Chicago: Chicago Review Press.
  • Nordland, Odd. 1969. Brewing and Beer Traditions in Norway. The Norwegian Brewery Association, Universiteitsforlaget. Norway: Mariendals Boktrykkeri A/S.
  • Patton, Jeffrey. 1989. Additives in Beer: Adulterants and Contaminants. Exeter, Great Britain: Patton publications.
  • Unger, Richard W. 2011. “Gruit and the preservation of beer in the middle ages.” Special Topic Issue: Medieval Brewing. AVISTA Forum Journal. 22: 1/2: 48-54
  • Verberg, Susan. 2018. “The Rise and Fall of Gruit.” Brewery History Journal. The Brewery History Society 174: 46-78. ResearchGate.