How To Make Nutrient Agar Plates At Home?

  1. Buy nutrient agar from Amazon or Ebay. One pack contains 12.5 grams of nutrient agar which is for 500ml water.
  2. Measure 500ml (17 fl. oz.) bottle water (tape water or filtered water will do) with measuring cup and pour it into a clean steel stock pot (you can add up to 550ml, which wouldn’t affect medium solidification).
  3. Dump the nutrient agar into the stock pot and gently stir  with a stainless steel spoon to mix nutrient agar with water.
  4. Slowly heat the stockpot to boil the water and gently stir until the media is completely clear (no visible agar particles). Don’t let agar sit at the bottom of the pot. You will fry the agar. Please keep stirring during heating. You may stop boil and let it sit for 5 min to check if it is clear or not. This step may take longer than 15 minutes. Just be patient. Incompletely dissolved nutrient agar will give you unsolid medium or the medium is fragile. If too much water is evaporated just add some extra water in the pot. You can add a little bit more than 500ml, there is no any problem, but don’t add too much water (over 550ml).
  5. Once the liquid medium is clear pour it into your petri dishes one by one. Just let medium cover the bottom which is enough to grow microorganisms (around 20ml for one 90x15mm petri dish). The medium contains enriched nutrients which are excess for bacteria growth.
  6. Cover each lid immediately after pouring to avoid the bacteria in the air fall into your petri dishes. You can pile up the petri dishes but you have to be very careful since you can flip over the light petri dishes.
  7. After 3 hours (best overnight) the liquid medium should become solid now. If you see excessive condensate water on the lid, gently take off lid and drip water off the lid, and put it back to the dish.
  8. If you don’t use it right away, just pile agar plates up and wrap them with food wrapping film/membrane and store them in your refrigerator (To avoid contamination and water dripping to the medium, please put them upside down (medium on the top)). These agar plates should be used as soon as possible. Bacteria can grow on the plates even you store them at fridge since the medium contains enriched nutrients.

Don’t have time to prepare the LB nutrient agar plates by yourself? You can purchase pre-made nutrient agar plates. For the instruction on how to culture bacteria with premade nutrient agar plates please click here.

Should you have any questions please feel free to contact us at Good luck with your biological science fair project.