How to culture Effective Microorganisms

Today I’m excited to teach you all about these good microbes and how to make effective microorganisms.

They improve the soil, increase plant health and yield, help keep pests away, and are some of the most important beneficial bacteria and yeasts in the world.

Effective microorganisms (occasionally called efficient microbes) can be purchased as a “mother culture,” which is a liquid that contains the specific species mixed at specific ratios.

This is done in a lab – you can’t make it from scratch – but you can get this mother culture and then make 20 times that amount. This not only saves money but also wakes up the dormant microbes, making them more effective.

That process is called activating the effective microorganisms. It’s a fermentation, like wine and yogurt, and today I’m going to give you my own effective microorganisms recipe.

I’m not going to get into the details of what it is and why you should make it because this post is just about how to make effective microorganism solution (I’ll give you a link to more info at the end of the post), but I will just say that I believe this is the most important thing for most people to bring into most gardens. I’ve seen seemingly miraculous results with it.

Now, EM Effective Microorganisms® (it’s called EM or EM1 for short) is actually a brand name. I tend to use the term generically like ‘Band-aid’ although I don’t even use the EM product. I actually use a similar product made by SCD Probiotics.

But both brands are great, so go with whichever you can get your hands on.

The Steps For Making Effective Microorganisms

1. Mother culture. First, you need a mother culture. The one I’ve been using for 10 years (and eventually started selling) is called ‘ProBio Balance’ (you can get it here).

2. Molasses. Get some unsulfured blackstrap molasses, from me or from the grocery store. Unsulfured is important because sulfur is used in molasses to actually kill microorganisms, while we’re trying to multiply them. Blackstrap is important because it’s lower in sugar and higher in nutrients. Organic is not all that important for this but certainly doesn’t hurt.

3. Container. Find a used plastic container with a tight lid, like a water or soda bottle. Any size will do, but I usually make batches in 1-quart, 2-quart or 1-gallon containers. If you’re lucky enough to have a carboy (pictured above), that will work too because it allows the gases to escape that are formed during fermentation. But if you don’t have that, the reason plastic is nice is that it has some flexibility and can handle the gas pressure better than a regular glass container.

4. Water. Fill the bottle approximately half full with hot water – not boiling, but something that’s slightly too hot to take a bath in. If you can use spring water or dechlorinated water, that’s great, but I’ve made this plenty of times with city water with chlorine or chloramine in it and it works fine as long as it’s not over-chlorinated – the microbes probably even clean that up because some of them are detoxifiers.

5. Mix in the molasses. Add the unsulfured blackstrap molasses to the water at 4% of the container’s volume (table below). The heat coupled with your swishing (which you can commence forthwith) will help dissolve it.

6. Mix in the mother culture. Add the EM1 or ProBio Balance at 5% of the container’s volume (table below).

7. Nutrition. This is a bonus step. You don’t have to do it, but it will add some more nutrients in there. If you have sea salt or kelp powder or sea minerals, add one of those in at 0.25% of the container’s volume.

The percentages don’t add up to 100% because I leave a 5-10% air space on top. Also note that while I’ve given fairly exact numbers below, you don’t have to be nearly that exact. Just try to use a little more EM than molasses.

8. More water. Fill the rest of the bottle up with more hot water, leaving an inch or two of space on top.

Container Size

Hot Water (80-85%)

Molasses (4%)

Mother Culture (5%)

Sea Minerals (0.25%)

1 pint

1 ¼ Cups

1 ¼ Tbsp

1.5 Tbsp

¼ tsp

1 quart

2.5 Cups

2.5 Tbsp

3 Tbsp

½ tsp

2 quart

5 cups

5 Tbsp

6 Tbsp

1 tsp

1 gallon

10 Cups

9. Shake. Gently, but firmly, like you’re playing shaker in a Sergio Mendes song – not like you’re a machine that shakes paint cans.

10. Warmth. It will do best to sit somewhere between 90-110 degrees Fahrenheit, so put it in the warmest part of your house. I actually put mine in my oven with just the oven light on, and a post-it note on the ‘Bake’ button as a reminder that it needs to be removed if any cookies are to be made (learned this one the hard way). It will work okay at 70F but will take a lot longer.

11. Leave it. I leave the cap off for the first 24 hours, but after that, I screw it on tight because this is a fermentation (without air). It will take at least 1 week until it’s okay to start using, and more like 2-4 weeks until it’s really good (or 6-8 weeks if you can’t find a warm place for it to sit). Even at a warm temperature, it’s nice to give it 1-3 months to reach peak perfection.

12. Burp it. If you don’t have a carboy, you’ll eventually want to ‘burp’ it daily by simply unscrewing and screwing the lid back on, to release the gases that will start forming after 2-5 days depending on the temperature.

13. Test it. Once you’ve been doing this for a while, you can get a feel for when it’s done by smell and taste, but I still like to do a test with pH paper (or a pH meter) that gives readings in the 2.5-4 range. Anything below 3.8 and above 2.7 is okay, with 3.0-3.5 being ideal. 3.8 and above are no good.

14. Use it. I use it monthly as a spray on my plants, soil, and compost, at 1/2 cup per 1000 square feet, mixed with at least 8 gallons of water (that’s a 1:250 ratio).

15. Store it. At room temperature, not in direct sunlight, but not necessarily in the dark either, as it seems to prefer a little indirect light. The mother culture has an expiry date, but in my experience will last a year beyond that. Your homemade activation is most effective within the first month after the pH drops below 3.8, but will store for months after that. If you make a few bottles, once the activation is done, you can use one bottle to fill the rest up to the brim so as to store them without air, and then just use that bottle first. A little air is okay during the fermentation, but not during storage if you want it to last a long time.

By the way, if you order the ProBio Balance mother culture from me, I’ll give you free access to the course in my Smiling Gardener Academy that gives a more advanced, detailed process for how to make effective microorganisms (plus it’s all on video).

For more info on all of this, check out my SCD Probiotics post.

And if you have any questions, feel free to ask down below, too.

⅔ Cup