Effective Microorganisms (EM) can be activated so that you end up with approximately 20 times the original amount.

This isn’t necessary, but it is often done to save money. Application rates are the same either way.

Ingredients (per 1L)

1 part EM (40ml)
1 part Unsulfured Blackstrap Molasses (40ml)
20 parts dechlorinated water*, not distilled or reverse osmosis (800ml)
Clean, airtight bottle (1L), generally plastic with screw-on lid (not glass) – can use bigger jugs, too
pH paper is useful to determine if your batch is good

Optional (I currently sell the last 3 in 1L bottles):
1/2 Tbsp rock dust for minerals
1/2 tsp sea minerals for many good things
1/2 tsp liquid kelp for many good things
1/2 tsp liquid fish for many good things

*Dechlorinated water isn’t necessary, but worthwhile because chlorine can kill microorganisms. Tap water can be dechlorinated by letting it sit out for 24 hours. If the tap water has chloramine (such as in Victoria), a small amount of humic acids will help to tie it up (1/2 tsp per litre).


  1. Heat some of the water to 100-120F
  2. Pour water into your bottle and dissolve molasses
  3. Mix in any of the optional ingredients and then mix in the EM
  4. Add the remaining water and stir and/or shake.
  5. Tighten lid and keep warm (80-100F is optimal)* for at least 1 week
  6. After the first few days, the container needs to be burped every day or two, as gases are formed that will expand the bottle.
  7. Can be used when pH is below 3.8. It should also have a sweet smell (it may smell a bit when you initially take off the cap, but if that persists for more than 10 minutes of the cap being off, or if the pH is 3.8 or over, it should not be used; note that if you add fish and/or kelp, it may have a smell to it, but that is okay).

*Can be kept warm in an oven with the oven light on (put a note on the oven), in a cooler with a terrarium heater or some other heat source, or many other ways. The whole process can be done at 70F, but it will take 6-8 weeks, and the odds of failure are higher. Even keeping it warm for the first few days is helpful.


EM Mother Culture stores for 18-24 months, or potentially a few years.

Activated EM stores for a month or two, or potentially 2 or more years if it’s a good batch.

Cooler room temperatures will keep it longer (10-20C is optimal). Store it in the dark or indirect light with the lid on tight.