A lot of credit for the methods followed here are due to Bootleg Biology and Andrew “Gus” Addkison’s post on Craft Commander with a lot of inspiration also coming from a The Mad Fermentationist and the Jester King Blog.

Forage and propagate yeast

  • Collect edible flowers and place them directly from the plant into sanitised centrifuge tubes with lids. Scissors and tweezers were used to prevent contamination from my skin. I used no rinse sanitiser but rinsed it off. Six samples collected per flower.


  • Prepare wort at 1.025-1.030 SG. 1g DME per 10ml. 30g used in 300ml. 100ml evaporated. With 200ml remaining the SG was 1056. To reach the preferred gravity:

56 x 200/30 = 373ml
To be cautious 150ml was added. SG was now 1033.
33 x 350/30 = 385ml

  • This was sometimes hopped wort in 2017. I will omit hops in 2018 to encourage bacteria, accepting that I will have a lower success rate.
  • Wort cooled to room temperature and aerated.­
  • 25ml of wort added to each tube. Lids were fitted and each tube was shaken to further aerate.
  • Left in dark at room temperature and waited for bubbles and yeast sediment. Shake occasionally.
  • Once fermentation had started, after 2-3 days, flowers removed using aseptic techniques. A spirit lamp was used. The test tube was held close to the flame and tweezers wafted through the flame. Lid and opening of the tube also wafted through the flame before closure, without melting the plastic.
  • Once fermentation activity had finished the most lively and healthy smelling were used to inoculate conical Erlenmeyer flasks with 250ml of aerated wort at 1.040 S.G. If promising but different smelling tubes resulted from the same flower type they were propagated in seperate flasks.  In 2018 hopping will be minimal, below 5 IBU. Acidifying the wort will be further researched as an alternative way to discourage unpleasant bacteria.
  • Flasks left for two weeks to ferment out and, where the aromatics were promising, stepped up in quantity and alcohol tolerance with 500ml at SG 1.045-1.050. As above, hopping will be kept lower in 2018.
  • If the pH is less than 4.7 botulism causing bacteria, which are rare, are inhibited and tasting it should be safe but do at own risk. pH, final gravity recorded. Sniff and taste test.
  • Where multiple successful flasks remain for one flower type, blend together.

Base beer brewing

My aim is to produce a saison type base beer.  The recipe for the initial brew is shown below. Generally, the strength will be around 6% ABV and the colour will be around 6-8 SRM.  I will tweak the quantities for pilsner, Vienna, wheat malt and honey and tweak, switch or omit the cara Munich. I only want a subtle hop character and may reduce the IBU further to encourage bacteria. In 2018 I will keep hopping between 7-15 IBU. I will use various European hops. For the control sample various commercial saison yeasts will be used.


OG 1.062      FG 1.012      ABV 6.4      SRM 8      IBU 20

  • 55% Pilsner malt
  • 25% Vienna malt
  • 10% Pale wheat malt
  • 8.5% Sussex honey
  • 1.5% Cara Munich (45L)
  • 27g East Kent Golding (AA 5.85%) at 60mins
  • 27g Saaz (AA 3.07%) at 20mins
  • 23g Styrian Golding (AA 2.00%) at 0mins
  • WLP 565 Belgian Saison Yeast

mash at 66C for 1 hour. Boil for 1 hour. Honey 5mins from end of boil.

Once cooled and aerated, single source wild yeast added to a 1 galon demijohn.  Commercial yeast added to remaining wort as a benchmark.

A summary of all base beers brewed so far are shown below:

recipe summary table

Once cooled and aerated, single source wild yeast added to a 1 galon demijohn. Commercial yeast added to remaining wort as a benchmark.

The demijohns were left until fermentation was complete. After 5-6 months the airlock was stationary, no bubbles were rising in the demijohn and the gravity was below 1.010. In this way they were conditioned on the yeast cake (with no ill effects on flavour).

Next year I will treat fast acting yeast strains differently to encourage their natural behaviour, racking off the ale and reusing the yeast as soon as the gravity is below 1.010. This might allow a fast acting house strain to develop for more sessionable everyday ales alongside the slowly aged ales. I will take more gravity readings in 2018 having shied away from this in 2017 to avoid oxidation. Others recommend racking once gravity readings are stable. If I take more gravity readings I could follow this approach. Flushing with carbon dioxide is an option if I am worried about oxidation.

The finished ales were either bottled, with priming sugar added, or blended with other single flower source ales.  pH and gravity reading were taken and sensory testing notes recorded (here). The ales were blended to taste but some unblended ale was bottled for comparison and to bank the yeast.

the yeast cake from the demijohns was then blended and reused for subsequent brews. Quantities of yeast slurry were not very scientific. I’m not counting cells under a microscope at this stage. My logic was that healthy yeast can step up in volume 1:10 so the yeast cake from a 4.5l demijohn could inoculate 45l. I’m assuming it’s not very healthy after 6 months so doubling that ratio (1:5).