Stir it Up! Yeast Starters and Stir Plates

Having had my last two batches of beer turn out not so great, Dave finally convinced me to make a starter. He knows that the majority of home brewers who come into Noble Hop to get liquid yeast are not making starters. This is a big concern for him because it is highly likely that most people are under-pitching and although it may not have such obvious consequences as mine, their beer could turn out so much better with just a little forethought. We decided that it would be beneficial for me to write this blog post about my first starter to show how little effort is required to massively bring up the quality of your beer.

Note: This post is for liquid yeast. Dry yeast packets store for longer and need only to be rehydrated. In John Palmer’s 3rd edition of “How to Brew” he explains that most dry yeast contains all the nutrient needed to pitch into the wort, if a starter is made, these nutrients might be prematurely exhausted.

If you’re like me then you decide on a brew day, do almost nothing in advance, grab your ingredients and end up having a fun, yet long day. The yeast will do its thing as long as the temperatures are right…right? Wrong! If you are trying to make a high gravity beer or “big beer” as they are sometimes called, or a lager, then 100 billion cells is just not going to cut it. Not to mention the fact that there WERE 100 billion cells on the day the yeast left the lab, over time the cell count will naturally decline which is why yeast that is 6 months old is basically useless. Yeast has a “made on” date stamped on the package, ideally the yeast you buy will be under 3 months old. See this fancy chart I took from the most reliable source, the Internet.


I can hear you saying the same things to yourself that I have already said, “but my beer has turned out decent, even good every time!” and “the yeast package says it’s good for a 5 gallon batch, how could they deceive me?” Now listen, I don’t doubt that your beer tastes good but here are some of the things that can come as a result of under-pitching and believe me, its not worth the risk (plus your beer can be better than good!)

Off flavours that can develop include: buttery (diacetyl), alcoholic, cooked corn, solvent-like, sulfuric compounds, cloudiness and increased ester production. If those things aren’t bad enough there is also a significant increase in the chance of infection because without sufficient yeast the fermentation is slowed and there is a longer lag time (time it takes for the yeast to start producing alcohol). The lag time is where infection most often occurs and so the shorter the better. After I pitched my yeast starter the airlock was bubbling within 7 hours!

Now that you are thoroughly convinced that a starter is the only way to give your yeast a fighting chance it is time to introduce to you the stir plate. This device was invented to make your starter basically fool proof. If you are going to spend the extra time making a starter you might as well make the best starter you can, did I mention that it takes a lot of responsibility off of your shoulders? Here’s why: Yeast needs oxygen to grow (this is why we aerate our wort before pitching our yeast on brew day) the stir plate literally stirs your starter constantly so oxygen is always flowing through it. This increases the rate of growth immensely. In John Palmer’s book, “How to Brew” he explains making a starter with an airlock, and recommends making it 4-5 days before you plan on brewing, with a stir plate and no airlock (we want the oxygen) you only need 1-2 days to get sufficient yeast growth and it only takes 20-30 minutes max! Here is another very scientific graph to further illustrate my point:


Graph taken from

How to Make a Yeast Starter
You will need:

  • 1 or 2L Erlenmeyer flask
  • DME (dry malt extract)
  • Sanitizer
  • Liquid Yeast Packet (100 Billion Cells)
  • Stir plate with magnet
  • Bottle brush for stirring
  • Aluminum Foil

Step 1:
Measure out your DME. Depending on the gravity of the beer you are making you will need to adjust the amount of extract you use.  A big beer may even require a 5L starter. Use brewer’s friend calculator to help figure it out.

For a basic starter at 1.040 O.G. you can use 2 cups water to ½ cup DME.

Step 2:
activate your smack pack

Step 3:
Clean and sanitize your flask

Step 4:
Fill flask with measured amount of water (I used 2L).

Step 5:
Add DME and stir bar, heat will not affect the magnet. The Erlenmeyer flask can go directly onto the stovetop.



Step 6:
Bring to a boil, and boil for 10 minutes.


Step 7:

Cool to 70F in ice bath


Step 8:

Pitch yeast


Step 9:
Cover with sanitized foil


Step 10:
Place flask on stir plate, turn stir plate on, leave on for 1-3 days

Step 11:
Cool flask in refrigerator to separate beer from yeast


Step 12: pour off beer using the provided keeper magnet to avoid pouring out the magnet

Step 13: On brew day pitch yeast to cooled, aerated wort. Use keeper magnet to avoid pouring out magnet.

And there you have it! It is super easy and extremely effective. Your beer will go from good to great. Happy Brewing!

Here are a couple shots of the stir plate using just water.



1 thought on “Stir it Up! Yeast Starters and Stir Plates

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