Growing high brix plants

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Maximum Yield - for Growing Professionals

Building up the Brix for Healthier, Nutrient-Dense Crops
Harley Smith | March 10, 2014
Building up the Brix for Healthier, Nutrient-Dense Crops
Source: Gyuszko / Dreamstime.com

Takeaway: As a measurement of the sugar content in the sap, brix is an important indicator of both a healthy plant and a flavorful, nutrient-dense crop. Here’s how to boost the brix to grow the best of the best.

The best organic farmers often boast about growing nutrient-dense, high-brix plants. But brix is still a foreign concept to many indoor growers. Brix is a measurement of the sugar content in the sap, expressed as a percentage. Generally speaking, the higher the brix, the healthier the plant. In fact, some organic gardeners claim that if you can achieve a brix level of 12% or higher, sucking insects won’t even recognize the plant as food! Furthermore, there is a direct proportional relationship between brix and the quality of the finished produce. High-brix plants are healthier, tastier and higher in nutrients than low-brix plants, and brix offers an objective measurement of how well your plants are doing. So if you want to consistently grow the best of the best, taking regular brix readings will help you reach your goal.

Brix measurements are taken with the aid of a brix refractometer. The more sugars and dissolved solids in a sap sample, the more the mixture bends the light that passes through it. A brix refractometer reads how much the light bends (refracts), and displays the results as a percentage of sugars in the sap. And it’s easy to use—just take a leaf sample, roll it into a ball and squeeze a couple of drops onto the glass slide of the refractometer. Then look through the hand-held device towards a light source, and read the brix number on a graduated scale. If you want an even more accurate measurement, digital refractometers are also available. Check with your local hydroponics store for your best options.

The more efficiently your plants take up water and nutrients, the higher the brix. Since organic biostimulants improve the uptake of minerals, the judicious use of additives such as amino acids, humic and fulvic acids, and seaweed extracts can help improve brix. The proper balance of minerals in the nutrient solution can also have a positive effect, particularly the potassium-to-nitrate ratio. Here are some suggestions for improving the brix of your favorite crops.

Increase the Potassium-to-Nitrate Ratio

Taking a brix measurement is standard operating procedure for hydroponic crop advisors in Europe. For example, if a leaf sample in a hydroponic tomato greenhouse shows low brix, often the first thing the consultant will recommend is raising the potassium-to-nitrate ratio until the brix reaches the target level. That way, nutrient problems can be avoided before the first signs of deficiency appear. Once visual nutrient deficiencies appear, the plant is already suffering and may not ever be able to reach its true genetic potential. Taking brix readings and making adjustments will help prevent problems before they happen.

Excessive nitrates burn carbohydrates and reduce brix. In fact, nearly 30% of the energy of photosynthesis is used just to assimilate the nitrates. So to ensure high brix, don’t give plants more nitrates than they need. Excessive nitrates produce large cells with thin cell walls, making them a target for pests and diseases. And since the sugars are burned to produce more top growth, root growth can become restricted and fruit and flower production can be delayed. A brix refractometer can show the signs of excess nitrates before it’s too late.

If nitrates are adequate but brix is still too low, it may be beneficial to increase the potassium levels. Potassium is a catalyst for carbohydrate metabolism, helping to increase brix. A grower has three choices for increasing the potassium-to-nitrate ratio: lower the nitrates, increase the potassium or do a little of both. Once you find the sweet spot, no pun intended, the brix should start to improve.
Use Humic and Fulvic Acids

Humic and fulvic acids are intermediate chelators, helping plants take up important trace elements. Since trace elements activate enzymes in the plant, the plant is able to do more chemical reactions per second, resulting in higher brix. Iron uptake is especially important. In nature, humic and fulvic acids hold onto iron ions like a claw and make them more available to the plant. Iron is a catalyst for chlorophyll synthesis, the green pigment in plants that actually manufactures sugars during photosynthesis. In fact, if iron availability is at optimal levels, plant genes will be activated to produce more chloroplasts to hold the extra chlorophyll, turning the plant into a more efficient sugar-making machine. The result? Higher brix.

Fulvic acid can be used as a foliar spray. The fulvic acid molecules transport the iron and other trace elements through the cell membranes, and release them inside the cell where they are needed the most. The carbon skeletons can then be metabolized by the plant. For best results, use a natural surfactant such as yucca extracts when using fulvic acid as a foliar feed. The surfactant prevents water from beading up on the waxy leaf surfaces, so the foliar spray spreads out in a thin film for better absorption by the leaf. Better absorption of iron results in higher brix.
Use Amino Acid Blends

Amino acids are also intermediate chelators, improving the uptake of minerals. In particular, amino acids improve the uptake of calcium. Certain amino acids stimulate root cells to open up calcium ion channels, allowing calcium to be taken up many times faster than simple osmosis. Calcium strengthens the stems and vascular system of the plant, allowing water and minerals to be taken up more efficiently. The more efficiently water and minerals are assimilated by the plant, the higher the brix.

I discovered the relationship between amino acids and brix when growing romaine lettuce one summer in an outdoor NFT system. I had just purchased my first brix refractometer, and I was taking brix tests on everything I could get my hands on and comparing the readings with brix charts. Brix charts indicate quality, either low, medium or premium quality, depending on how high the brix is. After I started using amino acids in my nutrient solution, the brix in the leaf tissue of my lettuce was off the charts. In fact, the brix level was so far above premium quality that statistically I’d have to create a new category for it. Every store and every restaurant that tasted the produce bought it at 20% above premium cost. We also went through three hard frosts without losing a single leaf. I found out later that for every 1% increase in brix, there is a half-degree lower freezing temperature. So the improved calcium uptake provided by the amino acid blend resulted in higher brix, better flavors, longer shelf life and higher sales prices.
Use Seaweed Extracts

Seaweed extracts also have a positive effect on brix. Seaweed extracts include mannitol, a natural sugar that chelates micronutrients and makes them more available to the plant. Seaweed extracts are also loaded with natural plant growth hormones that stimulate cell division. When used at the root zone, seaweed extracts stimulate cell division of root cells, resulting in more lateral root growth and greater root mass. Improved root growth creates more surface area for the uptake of water and minerals, further improving the brix of the plant. Seaweed extracts are synergistic with other organic biostimulants, so using a combination of additives is better than using any single additive alone.

Remember, plant growth is part of a complex system with many variables, so don’t expect a magic bullet to increase your brix overnight. Instead, use your refractometer along with other management tools in your garden. Light levels, air flow, pH, electrical conductivity and nutrient balance all affect brix in one way or another, and continuous improvement is the goal. I suggest you start by testing the brix of your healthiest, most productive plants and using the reading as a gold standard. Then take small steps to see if you can raise the brix in subsequent crops. As your brix goes up, you will soon see the relationship between brix and quality, and you will better enjoy the fruits of your labors.
Written by Harley Smith
Profile Picture of Harley Smith
Harley Smith is the director of research for NPK Industries. A veteran in the hydroponics industry, Harley has more than 18 years of consulting and educating experience. He is regarded as an expert on plant nutrition and organic bio-stimulants, performing research and new product development in the US and Europe.

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Maximum Yield - for Growing Professionals

Fix Your Brix: Grow Top Quality Crops with High Brix Gardening
Monica Mansfield | December 1, 2015
Fix Your Brix: Grow Top Quality Crops with High Brix Gardening

Takeaway: Growing food is good. Growing food full of nutrition and flavor is better. Often overlooked by gardeners, high brix levels are important to get the most out of your fruits and veggies. Monica Rakowski explains why high brix is good and how to increase its levels in your plants.

What is brix? As gardeners, we strive to grow a delicious, nutritious, pest-free harvest. We buy the right fertilizers and pesticides, measure pH and PPMs, prune, stake and monitor our environment. Even with all of this effort, there is one measurement that many indoor gardeners overlook: the brix. Increasing this one measurement will improve the flavor, nutrition and shelf- life of your produce. It will also keep pests at bay.

Brix measures the total dissolved solids in the sap of a plant, which includes sugars, organic acids, vitamins, minerals, amino acids and phytonutrients. The higher your brix value, the sweeter and more nutritious your plant is. Brix has traditionally been used in the wine, sugar, carbonated beverage, fruit juice and honey industries. However, brix can be used with any crop.

Brix values can be measured with an instrument called a refractometer, which measures the refractive index of a liquid. A couple drops of sap or juice from the plant is squeezed onto the tool. When light strikes the carbohydrates, salts and molecules in the liquid, it bends or refracts. The more dissolved solids there are in the liquid, the greater the refraction, and the higher the brix value. If the fruit, vegetable or leaf does not produce juice easily, the best way to extract it is to use a mortar and pestle to smash them and then strain it through a mesh screen onto the instrument. You could also use a garlic press.

Dr. Carey Reams, who was a leader in high brix gardening, developed a chart of the poor, average, good and excellent brix levels in a variety of fruits and vegetables. By using this chart in conjunction with a refractometer, you can judge the produce you buy. Armed with these tools, you can find the highest quality farmers to buy from, or push your own garden to new limits.

You’ll find that produce from the grocery store is consistently on the mediocre side of the chart (and we wonder why kids don’t like to eat their veggies). In fact, our taste buds are an even better tool than the refractometer for measuring sugar content and nutrient density in our food. Sugar and mineral content are responsible for the sweetness tingling your taste buds, and if you start tracking the food you measure, you’ll find the tastiest, most nutrient-dense fruit and veggies have the highest brix levels.

Low brix values mean poor nutrition, which leads to pests. Pests are nature’s clean-up crew. They ensure natural selection in plants. Only the strong survive. Plants with a brix value over 12 per cent are much less likely to have pest issues, if they have them at all. It’s only when a plant is weak and sick that bugs attack to clean up the mess. When a plant has deficiencies, simple sugars and incomplete proteins leak out to the surface of the leaves and stems, drawing the bugs in for lunch.

There is a story of two farmers whose fields were right next to each other. One farmer took care of his soil so that his brix levels were high, and the other one didn’t. One terrible year, an infestation of grasshoppers attacked the farmer’s crops who had the low brix. If he stood in his field, swarms of grasshoppers swirled about him. However, if he took just a few steps over to his neighbor’s field, there wasn’t a grasshopper to be found. The farmer with the high brix levels had such healthy crops that the grasshoppers barely noticed them.

Not only will your harvest be better for you, but it will last much longer. Fruits and veggies with high brix levels will not rot and mold. They simply dehydrate. This is news to most people who are used to grocery store produce going bad within a few days of buying it. It may lose enzymes and vitamins with time, however, the mineral content remains the same. Even if you can or freeze your produce, you will still gain the same exceptional nutritional benefit a year later.

Higher brix levels also mean your plants will have a lower freezing point, which means they will be tolerant of extreme temperatures. Outdoors, this can be helpful when dealing with first and last frost.

Now that you see the value of high brix levels in your fruits and veggies, you’re probably wondering how to get those higher levels. As always, it starts with the soil.
How to Increase Your Brix

The key to increasing your brix levels is to increase the mineral uptake so the plants can produce more sugars. You do this by focusing on building your soil so that it is full of organic matter, beneficial bacteria and fungi, and the proper nutrient ratios. It can take four to five years to build truly healthy soil. Indoors, you can build a soil with the proper amendments that will do the job quickly.

A simple soil recipe would be to mix one-third compost, one-third peat or coco coir, and one-third vermiculate as your base. Then add beneficial microbes, and food for those microbes. Earthworm castings, mycorrhizal inoculants, compost teas, humus, amino acids, humic and fulvic acids, rock dus, and seaweed are the best soil additives to use if you want higher brix.

Beneficial microbes have a symbiotic relationship with plants. They attach to the roots, eat the root exudates, and then feed their waste back to the plant in a form that is more readily available. Sunlight plays an important role in a plant’s ability to produce sugars. In fact, harvesting on a cloudy day can result in lower sugar content, and therefore lower brix levels. The benefit of growing indoors is that you have plenty of light.

Iron uptake is also important for this reason. Chlorophyll, the green pigment, manufactures sugars during photosynthesis, and iron acts as the catalyst. If iron is readily available, plants will efficiently produce sugar. Add humic and fulvic acids to the soil to make iron more readily available to your plants.

Seaweed is excellent for increasing root mass, chelating micronutrients to make them more available, and stimulating cell division. The increased root mass offers more surface area for minerals to be taken up into the plant. Amino acids improve the uptake of minerals, specifically calcium. Calcium allows water and minerals to be taken up easily by strengthening the stem and vascular system of the plant.

Be cautious not to give your plants too many nitrates. They burn carbohydrates and reduce brix. Too many nitrates will result in large cells with thin cell walls, which attract pests.

If your goal is to increase brix, use minimal bottled fertilizers. Their salts can disrupt the soil environment and the microbes that live there. It is not overly complicated to create the soil that produces a high brix. Following a few good soil practices will deliver a delicious reward.
Written by Monica Mansfield
Profile Picture of Monica Mansfield

Monica Mansfield is an avid gardener and the former owner of KP Indoor Garden Supply in Lakebay, Washington. She is passionate about gardening, sustainable living, and holistic health. Monica writes about these topics in a column for her local newspaper and on her blog, The Nature Life Project. Full Bio

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Thanks @Dewb, those were 2 very interesting reads. I use a Brix refractometer for homebrewing, I’m using Flora Micro & Bloom, roughly following the Lucas Ratio. It’ll be interesting to see where the plants score. I’ll test a few plants throughout this current grow of @LED_Seedz Strawberry Cream. I might learn something and be able to share with OG.

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Some high brix sap from today :heart_eyes:


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Great reading right there. That’s one reason I love the Nectar For The Gods nutrient line. High brix!!

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Inspiring articles, thx for the share. I absolutly need to get one refractometer now lol

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I am gonna start collecting this to put it on my pancakes. ,:yum::rofl:

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@Viva_Mexico what’s the strain?

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That is cookies kush from Barney’s farm.

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I bought one, never used it. :grin::rofl:

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On my side i can say the same for ec meters and ph meters ^^ trade ? lol

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Do cannabis leaves have enough moisture to place a drop on a refractometer?

Can’t say I’ve ever tried the leaves. If you use several thoroughly shredded/crushed leaves and squeeze some between 2 spoons, it should work. I squish the petiole with hemostats over the sample area of the refractometer.

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Found these today. Went out of town for spring break came back and found sap and powder mildew

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Neato. I had a purple orange kush that did the exact same thing. You’d find little balls of orange resin buried in buds.

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Anybody got any information relating Brix measurements to optimal harvest time in cannabis?

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