How To Make A Marijuana Nutrient Solution

In the growing and flowering stage of the marijuana plant you use at least two different kinds of fertilizers. We are going to make a cannabis nutrient solution step by step.

Demand for nutrients during the growing period

From the ratio between N and P, you can see if it’s pertaining a growing or blooming fertilizer.

A good example is the nutrition supplement PK 13-14, which complements the bloom fertilizer you use. In this case, the elements phosphorus (P) and potassium (K) are represented with a value of 13-14. For measuring fertilizers you need measuring cups. Eventually, we want 100 liters, with an adjusted EC and pH value.

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    Measuring cups
    Measuring cups

    Take out all the stuff you’re going to need. First the basic fertilizer components. To make 100 liters of a feeding solution you need to keep in mind that you’ll need a total of 200 to 400 cc of well-known hydro fertilizers.

    Furthermore you’re going to need the following tools:

    – measuring cups
    – syringe of 10 ml
    – pH meter
    – EC meter
    – pH- (down) nitric acid for growing, and phosphoric acid for blooming


    Mixing cannabis nutrients

    Fill the water tank. Preferably with lukewarm water of around 72°F (22°C). You avoid having to heat up the water for a long time that way. Depending on the EC value that you want to give to the solution, you measure the necessary basic nutrition based on the manual on the label and pour it through the water. Stir well, and keep track of how much nutrition you’ve mixed through the water. This way you get a good idea what it does to your EC values.

    Adjust EC

    Adjust the ec of marijuana nutrients

    Now you need to check if there are enough nutrients in the solution. That can be determined with an EC meter. If there aren’t enough nutrients in the water, and the EC is too low, you are going to need to add more nutrients. If the EC value is too high you must dilute the nutrient solution with water to lower it again. Stir well after each application and measure.

    A general rule of thumb for the EC value is hard to say. Common sense and the ability to observe are the most important tools regarding the EC. EC values are dependent on the preference of the grower, the type of plant and the size of the plant. Generally, you can say that the value of young plants can be about 1.5 and that this value for mature plants can go up to 2.5 and even higher. Click here to download a growing schedule with all the EC and pH values, temperature, humidity levels etc.

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    When you determine the maximum EC value
    In the determination of the EC value, we use of a so-called incremental scale. Which means that we increase the EC from the beginning, and right before the harvest. Every third or fourth day we increase the EC with 0.1, and we continually monitor the plants. Because marijuana plants show their discomfort as discoloration, distortion of the leave or other issues.

    Because the EC value is the only thing that changes, the discoloration etc, could have no other cause than an EC value that’s too high. As soon as further unexplainable discoloration appears we need to go back to the previous EC value, when the plant didn’t show signs of discoloration. An extra rinse isn’t a bad idea, to let the marijuana plants recuperate from the shock. A week later, when the plants have recovered, you can try to raise the EC level again. If you notice that the marijuana plants react in the same way again, then you know for sure that these plants have reached the maximum amount of EC levels for this harvest.

    Discoloration on leaves due to high EC
    Discoloration on leaves due to high EC

    The tap water may have a different hardness in different areas. The calcium, and other substances in the water, are salts that also add to the total number of nutritive salts of the solution. As we know now, some of these salts are desirable, but most of it is not. Sometimes a nutritional deficiency can occur even though a dripping solution with an EC of 1.8 is applied. When tap water already has an EC of 0.5, then we only add 1.3 EC (1.8 – 0.5) of nutrients.

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    Due to the large differences in the hardness of the water, the EC value of a solution that’s prepared in exactly the same way may vary greatly in various regions. There is no standard recipe for success. That’s why you have to pay close attention if you want to try out recipes from other growers.

    If you have to work with a relatively high EC due to the natural high EC levels, then there’s an increased chance of undesired salt accumulation around the roots. It that case it may be better to water them for a longer period of time, which also flushes out the slabs at the same time and keeps the root environment clean.

    Adjusting pH

    Adjust ph marijuana nutrients

    Now that you have a feeding solution with the right nutrients, you also have to check the pH values and adjust if necessary. These values should lie between 5.5 and 5.8. To decrease the pH value in the just-made feeding solution you fill a syringe with an acid, like nitric acid (pH down in the grow shop). You add a little bit of this acid, and stir it well before measuring the pH again. Repeat this until the pH lies between 5.5 and 5.8. Keep track of how much pH- you use, so next time you can work faster. If your pH value has decreased too much, you can raise it again with caustic potash (pH up). If this happens more than once it’s better to start all over again.

    Here’s how to adjust your nutrient solution depending on the EC or pH level:

    EC or pH LevelHow to adjust your nutrient solution
    EC too lowAdd more fertilizer
    EC too highAdd more tap water
    pH too lowAdd pH up (potassium hydroxide)
    pH too highAdd pH down (nitric acid or phosphoric acid)

    Get the right temperature

    Measuring the temperature marijuana nutrient solution

    The entire feeding solution is ready to go. Now only the temperature needs to be adjusted. Ideally, this should be around 72°F (22°C). If it’s too low, use a heating element to raise it. An aquarium heater is perfect this.

    For instance, you can circulate the water in the tank with a circulation pump. This way, no creatures or germs can settle and the water stays nice and fresh. Let your feeding solution sit for a while before you use it, so all substances can equally dissolve, react and stabilize. Sometimes it’s quite a hassle to add the right amount of nutrients to a container filled with water to get the correct EC value. But at some point you know exactly how much you need to add to get certain values.

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    FAQ About Preparing a Nutrient Solution for Marijuana Plants

    What’s the required volume of a nutrient solution for marijuana plants?

    Ideally, we would like to have 100 liters of nutrient solution, with an adjusted EC and pH value.

    How do I adjust my nutrient solution if my EC value is too high?

    If you get a high EC, you must add more water to the nutrient solution to lower it. Remember to stir the solution well after each application then measure your EC value again.

    What’s the ideal temperature of my nutrient solution?

    Ideally, this should be around 72°F or 22°C. You can use a heating element like an aquarium heater to raise the solution’s temperature if it’s too low.

    Have you made your own nutrient solution for your marijuana plants? Please share your comments or questions below.

    Happy Growing!


    Avatar for Robert Bergman

    Robert Bergman

    Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations. His passion for growing led him to develop his own Gold Leaf strain. Now, Robert is dedicated to sharing his knowledge with the world.... [Read full bio]


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