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Image by Frantisek Duris


A refractometer is a prism/type tool where light is refracted through the plant sap juices. The more "content" in the sap, the higher the "Brix" reading will be.​

A plant's Brix reading directly correlates with its general health, stress resistance ability, and nutritional density.


Brix is a Term Popularized by Carey Reams.

When used on plant sap it is primarily a measure of the carbohydrate level in plant juices. The instrument used to obtain a brix reading is the refractometer. Refractometers come in two basic styles, optical and digital. Both types work great. Here is how a refractometer is used: squeeze out some sap from a plant, put 2 drops of the juice on the prism, close the prism cover, point to a light source, focus the eye piece, and read the measurement. The brix reading is indicated where the light and dark fields intersect.  

What part of the plant is used for taking a brix reading? Whatever part you eat if it is ripe. If it is not ripe take the most recent mature leaves that have had full sunlight for at least 2 hours. Ideally measurements should be taken at the same time of day as you compare throughout the growing season.

A refractometer measures the amount of bend or refraction in the rays of light as they pass through the plant sap.

What causes light to refract as it passes through plant sap?

  1. The amount of carbohydrates in the juice.

  2. The amount of dissolved minerals in the plant sap.

  3. The amount of covalent bonding.

The above information belongs to High Brix Gardens. Further information about Brix can be viewed on their website at


"Picky-eater Insects Pass on High

Brix Plants." See Research Article...

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