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How to Mix Nutrient Solutions

ByBC

For the best plant results, it’s crucial to follow particular steps when making a nutrient solution. You need to add nutrients to the water in a specific order and be able to adjust its strength and pH. This article gives detailed guidance on creating nutrient solutions. It ensures they have the right Nutrient Element Ratio (NER), reach the desired strength measured by Electrical Conductivity (EC), and maintain the correct pH levels. By sticking to these steps, you’ll create a well-rounded and effective nutrient mix that suits your plants’ needs.

Overview

To mix proper nutrient solutions, there are several things that matter!

  1. Nutrient Element Ratio (NER) Matters: Cannabis plants do best when given the correct ratios of nutrients. These ratios change during the course of the grow. Supplier feed charts allow you to get the correct NER. See our article, “Cannabis Fertilizers, Supplements, and pH“.
  2. Electrical Conductivity (EC) Matters: EC is a measure of the salinity of the water. It essentially is a measure of the overall strength of the solution. If the EC is too high, the plant cannot drink water and will show symptoms known as “nutrient burn”. Following supplier feed charts produces solutions that are too high in EC. See “Understanding Electrical Conductivity (EC) and Osmosis“.
  3. Order Matters: Adding nutrients in the wrong order can create lock out, which leaves the nutrients unavailable to the plant.
  4. pH Matters: The pH of the solution affects the solubility of the nutrients. If the pH is out of the recommended range then certain nutrients will not be available to the plant.

In this comprehensive tutorial, we’ll explore the vital aspects of blending nutrient solutions. You’ll acquire a deep comprehension of the critical elements involved and receive step-by-step guidance on crafting your nutrient concoctions with the right Nutrient Element Ratio (NER), Electrical Conductivity (EC), following the correct sequence of additions, and achieving the ideal pH levels. By sticking to these instructions, you’ll be equipped with the expertise and abilities to craft nutrient solutions that are both well-rounded and efficient for your plants.

The NER and EC

As we explain in “Cannabis Feeding Fundamentals”, maintaining a balance is crucial when it comes to fertigation. It is essential to mix nutrient solutions that possess the correct Nutrient Element Ratio (NER) and maintain an appropriate Electrical Conductivity (EC). To ensure the proper NER, it is advisable to consult the feed charts provided by your nutrient supplier, as most of them offer specific guidelines tailored for cannabis plants.

However, it’s important to note that following nutrient supplier feed charts blindly can result in a solution that has an excessively high EC. Measuring EC is vital to prevent the solution from becoming too salty. If the water has high salinity, it can hinder plant uptake and potentially lead to dehydration, similar to the effects of drinking seawater. Therefore, maintaining the correct EC level is crucial for the overall health and hydration of your plants.

To learn more about NER and Cannabis Fertilizers, read our article, “Cannabis Fertilizers, Supplements, and pH”.

To learn more about the importance of EC, read “Understanding Electrical Conductivity (EC) and Osmosis”, and to know what EC you should be aiming for, be sure to see our tutorial, “Setting EC Targets”.

Why do nutrient suppliers create recipes that are too strong?

Nutrient suppliers provide dosage recommendations with the intention that growers achieve the correct Nutrient Element Ratio (NER) and then dilute the solution to reach their target Electrical Conductivity (EC) or Parts Per Million (PPM) levels. The dosage recipes are intentionally formulated to be stronger than necessary, as this allows growers to adjust the strength of their solution by diluting it while still maintaining the desired NER.

By providing stronger recipes, growers have the flexibility to increase the strength of the solution without compromising the NER. This approach ensures that each grower can tailor the nutrient solution to their specific requirements without sacrificing the essential balance of nutrients.

When Mixing Nutrients, Always Remember:

  • The feed chart recipes allow you to get the correct NER
  • Measuring EC allows you to get the correct dose

Creating Personalized Recipes

Nutrient companies typically recommend mixing nutrients at full doses and then diluting the solution to achieve the desired Electrical Conductivity (EC) target. However, it’s important to note that the base nutrients have the most significant impact on EC, while supplements often have a smaller impact. When the solution is diluted, all nutrients and supplements are reduced proportionally, regardless of their individual EC impact.

To have more control over the nutrient composition, it is advisable to create your own nutrient recipe by adjusting the quantities of the base nutrients while maintaining their ratios. This approach allows you to maintain higher doses of specific supplements while reducing the overall EC of the solution. By customizing the nutrient recipe in this manner, you can achieve a more precise nutrient balance that meets the specific needs of your plants.

Always provide base nutrients at the ratio recommended by the feed chart: For example, if there is twice as much “Bloom” than “Grow” in the feed chart, there should be twice as much in your nutrient solution. The total amounts can vary to achieve your target EC, but the relationship among them should be the same.

When considering supplement doses, consider their EC impact: Some supplements, like humic acid, have a negligible impact on EC and they may be given at full the recommended dose. Other supplements, like bloom boosters, make a large impact on EC, and must be dosed carefully. Be sure to read our article, Nutrient Supplements That We Recommend” for a deeper look at supplements.

420 Grow Help Nutrient Recipe:

General Hydroponics Flora Series

My nutrient feed chart for the General Hydroponics Flora Series nutrients is provided. It is set for the standard EC targets, with no grow specific adjustments. Be sure to read our tutorial, “Setting EC Targets“

The doses for the base nutrients (Flora Micro, Flora Gro, and Flora Bloom) are about half the dose that General Hydroponics recommends in their feed chart. However, most supplements are at or near their full recommended dose. If you are using this nutrient line, then you can follow these recipes with only minor adjustments to arrive at your specific EC target.

General Hydroponics Feed Chart

How to Mix Nutrient Solutions

Starting Water

As I explain in the tutorial, “Setting EC Targets”, You may or may not be able to use untreated tap or well water to mix your nutrients. The key consideration is the EC. Starting water must be lower than EC 300. The lower the initial EC the better. Using distilled water or water filtered through reverse osmosis is best. However, tap and well water may be used if they start less than EC 300/0.3.

Measuring Doses

It is important to accurately measure the doses in order to maintain the correct NER. Because of this, when the EC target is very low, as it is during the seedling stage, it is better to mix a stronger blend and then dilute the solution to your EC targets. To accurately measure doses of nutrients I cannot recommend graduated oral syringes enough. I use 10ml oral syringes and they come in a pack of 10. That is more than enough to assign one to each nutrient. They are accurate to fractions of a milliliter and they also read in teaspoons.

Order Matters!

Nutrients should be added to the water in a specific order to prevent lock-out. Silicon should be added first and given time to dissolve. Cal/Mag is second and should be added before the base nutrients. At the other end, Rapidstart, which has no impact on EC or pH should be added at the absolute end. Rapid start and H2O2 (when used) can be added after the final pH adjustment.

The Order to Mix Nutrients
  1. Add Silicon and give solution at least one hour to dissolve.
  2. Add Cal/Mag supplement
  3. Add Base Nutrients
    • First “Micro”
    • Second “Grow”
    • Third “Bloom”
  4. Add Bloom Booster
  5. Add Humic Acid
  6. Add SM-90 (I now use RAW Yucca as a wetting agent instead. See our article: “Recommended Nutrient Supplements for Growing Cannabis“)
  7. Measure and adjust the pH of the solution.
  8. Add Rapid Start
  9. Add H2O2 (if needed for reservoir)

Adjusting the EC of Your Nutrient Solution

To Raise EC: Make a high EC solution to mix with the low EC solution rather than adding nutes individually at the end.

To Lower EC: Dilute with “Cal/Mag water”: When dilution is required to reach the target EC, it is best to dilute with “Cal/Mag” water rather than plain water. This maintains the full dose of Ca and Mg and avoids potential problems that unbuffered coco may cause. Simply mix additional water with your regular dose of Cal/Mag supplement and use that to dilute the high EC nutrient solution.

Precision of your Target: Ideally, EC of your nutrient solution inflow will stay consistent, but it does not have to be precise. You can accept inflow EC values that are within 50 microsiemens (0.05 millisiemens) of your target. The EC within the root zone will fluctuate more than this anyways. However, if it is more than 50 points off target, you should adjust it.

Measuring and Adjusting pH

The pH of the nutrient solution affects the solubility of the nutrients in the solution. If the pH of the solution that you add is outside of the acceptable range, some nutrients will be unavailable to the plant.

Acceptable pH Range in Coco: 5.5-6.5

Coco does not buffer the pH of nutrient solution as effectively as soil and therefore it is critical to set the pH of the nutrient solution inflow within the range of 5.5 to 6.5. Because different nutrients are soluble at different pH, it is best to allow the pH to drift up and down within the range on successive fertigation events. During the majority of the grow your inflow pH should fluctuate around an average of 5.9. However, during the seedling and ripening phases it is best to target somewhat higher in the range (6.1-6.3). If you have any questions about pH, be sure to see our tutorial, “Measuring and Adjusting pH”.

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