How do I test the Brix of my marijuana plants?

Brix can help determine the health of your plants and is an easy test to complete.

For testing the Brix of your cannabis plants you will need:

  • A refractometer (we recommend a digital refractometer such as the HI96800)
  • A disposable pipette or small dropper bottle
  • Deionized water (or distilled water, or RO water)
  • Microfiber cloth
  • Your plant sample


  1. Turn on the refractometer by pressing the ON/OFF button.
  2. Once on, add a drop of deionized or distilled water (RO water can work in a pinch as well) to the the sample well. (The sample well is the small circular prism in the middle of the metal plate.)
  3. ZERO the instrument by pressing the ZERO button. *TESTING TIP! If you are in a brightly lit area, cup your hand over the sample well to block out excess light!*
  4. Wipe off the prism using a microfiber cloth or kimwipe.
  5. Take several leaves off of the plant you wish to test. Ball them up and squeeze the sap onto the sample well until the little prism circle is covered. (You can also take a small dish and use a spoon to mash the leaves until they release sap).
  6. Press the READ button. *Again, you can cup your hand over the sample well to block out excess light!*
  7. Record your reading.
  8. Wipe the prism off using a microfiber cloth or kimwipe. If sap gets stuck, simply flush the area with some extra water you used for calibration, and then wipe it dry.
  9. You are ready to measure your next sample!


For more information on Brix and cannabis, check out our blog by clicking HERE.