Sugar is our jam!
Well, here at Hanna it really is! But what does jam have to do with cannabis? Not too much, unless you are talking about sugar. Sugar is found everywhere: sodas, cakes, fruit, and even cannabis! Measuring sugar content is not hard or time consuming. Taking a few extra minutes here and there will help you to not only assess the health of your crop, but you will reap the benefits come harvest time.
First of All, Let's Talk About Brix
People check how sweet products are all the time while cooking. Does it taste sweet enough? No? Add more sugar. But what if you need to put an actual measurement on the amount of sugar in something? AND what if you can't taste the product that you need to test the sugar content of? Well, that's where Brix comes in. Brix is the measurement of sucrose (a simple sugar) in a substance. The actual unit is shown as % Brix. This is representing sucrose as a percentage of mass (weight, 100g). Brix is a measurement unit used throughout the food industry for measuring things such as jams, and in the agricultural industry to see if fruit is ripe to pick. Many people have heard of Brix if they have taken a tour of a winery and/or vineyard: the Brix of the wine grapes is tested as they get close to harvest time to determine the perfect time to harvest.
Growing Marijuana? You Should Care About Brix Too!
All plants perform photosynthesis, and because of that, they all produce sugar. You may be thinking, but if I bite a piece of celery it doesn't taste very sweet...and how can cannabis have enough sugar to measure?
When you get down to it, all living things use sugar to produce energy to live. Plants do the same thing. While they aren't eating cakes and cookies, plants use sugars to grow and thrive. Instead of just consuming sugar, plants produce it, and then store it until they need the sugar. Younger plants will typically have a lower Brix than mature plants simply because they are actively growing (and therefore using the sugars for energy).
Brix Can Help You Determine the Health of Your Plants
The quality and quantity of buds are key to have a successful harvest. In order to achieve this, the plants must perform photosynthesis at peak efficiency. This efficiency and the production of sugars can tell you if the plants are ready for harvest, or if they could be deficient in some of their growth needs (light, temperature, air, nutrients). In order to have bountiful buds, your cannabis plants will need plenty of sugar! Colors, aromatic properties, time to maturity, taste, and terpene profiles can all be affected by insufficient Brix. This can be very detrimental if you are trying to produce specific marijuana strains with specific looks and effects. Adequate Brix also indicates that the sap and immune system of the plant are performing well. The highest concentrations of sugar will be in the leaves of the cannabis plant - they tend to store sugar in the same area they produce it!
So, How High Should The Brix Be?
If you are looking to harvest your marijuana, you would want to wait until your plants measure between 12%-15% Brix. There are some cannabis strains available that are said to have higher Brix content (20% +). Anything below 12% indicates that either the plant is not mature yet, or that the plants are missing something crucial to thriving and survival. Adult plants with a Brix below 12% can easily be affected by pests and diseases, and have stunted growth.
How To Measure Brix
Measuring Brix can be done with either a mechanical Brix refractometer, or a digital Brix refractometer. A refractometer utilizes the way that light goes through a substance and then bends. That refraction is measured and then able to be correlated to characterize many different substances, including sugars. This simply means that refractometers are able to help you to determine the concentration of substances such as sugars in a sample.
Which Refractometer Should I Use?
There are two types of refractometers that you can consider for your testing needs: mechanical (also known as optical), and digital. Both types of refractometers are portable and able to be carried with you to wherever you need to do your testing. Mechanical refractometers tend to be less expensive than digital refractometers; they also tend to be smaller. Unfortunately, mechanical refractometers depend on your own eyes to determine the shadow line in the viewfinder. Have you ever used a kaleidoscope or a small kids telescope? It's a similar idea in terms of that you hold it up to the light after applying the sample, and you have to see where a dark line falls. Digital refractometers can have measurement curves built in for specific sample types (ie. Brix), to compensate for temperature differences. This gives you a much greater degree of accuracy. Plus, digital refractometers do the reading for you, and give you a readout on the screen,
|Mechanical Refractometer||Digital Refractometer|
|Simplest Design||Extended Range|
|Visually Determine The Shadow Line in a View Finder||Improved Resolution|
|Dedicated Meters for Specific Ranges||Removes Visual Uncertainty With Digital Readouts|
|Temperature Compensation for Measurements is Tricky||Automatic Temperature Compensation is Available|
|Resolution Can Be Poor||Some Models Are Extremely Accurate|
How To Measure Brix With a Digital Refractometer
Measuring Brix of cannabis is quick and easy with a digital refractometer such as the HI96800. When taking measurements, keep in mind that you do not have to, nor do you need to, check the Brix of every plant. Try dividing up your plants by quadrant and batch test (that way you have a representative plant from each area of the growing operation).
- Turn on the refractometer by pressing the ON/OFF button.
- 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.)
- 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!*
- Wipe off the prism using a microfiber cloth or kimwipe.
- 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).
- Press the READ button. *Again, you can cup your hand over the sample well to block out excess light!*
- Record your reading.
- 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.
- You are ready to measure your next sample!
The Brix Testing is Done - Now What?
It depends on what your Brix readings were at! Were they on par with being at least 12-15% Brix? Did you test when you suspected that the plants were ready for harvest? Then you should be good to go. If your Brix numbers aren't where they should be, there are some remedial steps you can take.
How to Boost Brix in Cannabis Plants
Low Brix in mature plants typically points to the cannabis missing a key growth factor - air, light, temperature, and nutrients. Strong grow lights can help stimulate higher levels of photosynthesis. The amount of light used should be tailored throughout the growth cycle to stimulate flowering as well. Keeping humidity and temperature levels up can aid in boosting Brix. In addition to tailoring the light schedule, the same should be done for watering and feeding the plants.
Commercial soil and hydroponic supplements are available to aid in the nutrition realm of growing cannabis. Some growers even add some molasses to their grow mixture ahead of the flowering time to boost Brix. Remineralization of soils can help your cannabis uptake trace minerals as well as key nutrients. Trace elements help lay the basis for successful photosynthesis. Checking your potassium to nitrate ratio could be key to keeping your plants well fed. If you have too many nitrates, the cannabis plants will actually have to use their stored sugars to process the excess nitrates. Humic, fulvic, and amino acids are known as activators, and can influence how your plants uptake nutrients such as iron and calcium (these are needed for photosynthesis to happen). Seaweed extracts can boost the micronutrients plants need to stimulate their cell growth.
Test the Brix in one plant, or in one area, apply a treatment, and then recheck the Brix later on in the day. If the treatment has a positive influence, then you know it is safe to apply to the rest of the crop.
Take your time and get to know the strains of cannabis that you are growing. Every varietal is different!
Charting your results can help you not only know when to harvest, but it can help you to troubleshoot issues. For example, did you apply a new nutrient solution, and then you saw a drop in Brix? Then maybe that solution isn't quite right for your crop.
For more information regarding how Hanna Instruments can help you with your testing needs, contact us, as firstname.lastname@example.org or 1-800-426-6287.
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Allison graduated from Bryant University with a Master’s Degree in Global Environmental Studies. She is passionate about nature, and how science is connected to the world around us. At Hanna, she provides an array of content and support to customers through the Hanna Blog, SOPs, and Data Sets.
Allison may be reached at email@example.com.