How to take brix measurements

Graytail;2129400 said:

I've been taking weekly brix readings from my flowering plants for a year now, so I decided to post a DIY for it.

Brix measurements can be tricky. You're measuring the percentage of "dissolved solids" in the sap of the plant, so if you test a crusty old leaf you'll get an artificially high reading. Less moisture=higher percentage of stuff in the fluid. Brix doesn't vary much across the plant, so it's not terribly important where the healthy leaf came from. It's more important to take the same sort of leaf from the same sort of place on every plant every time. I take a typical small 5-bladed leaf from mid-canopy. They're usually fairly plentiful - pretty crowded in there - lots to choose from.

Good brix readings for cannabis are 10-12.
Very good readings are in the 12-14 range.
Excellent readings are 14-16.
Spectacular readings can occasionally top 18.

If your results are especially high, be sure you're taking fair measurements.


Here's what I start with - vicegrips, a couple of thick metal slugs, a refractometer, and a typical healthy 5 bladed leaf.

I start by tucking the pertiole against the leaf and rolling/twisting it together.

Tuck it again, twist some more ...

I put the wad between the slugs and squish it carefully around the disks without releasing any juice ...

I reroll it, squish it for real and let a drop touch the prism ...

Flip it closed and take a reading ...

Reroll it, clean off the prism, and take another reading.

This is from a Carnival Cut I ran. I'll take a 17/17 any day.

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