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Best Hydroponic Nutrients for Weed

Last Updated: March 16, 2023By Joshua Mezher

growing cannabis

The advantages of growing marijuana indoors are many. One of the most important factors is the ability to control the environment. Hydroponics help give complete control of lighting, water, and air-flow. This indoor grow setup allows the plant to prosper and grow in a manner that is otherwise difficult in outdoor circumstances. 

The process of growing a cannabis plant outdoors and in a hydroponic setup is completely different. Since it’s a controlled environment, the plants require the utmost care and attention to detail.

Related Article: 10 Best Grow Lights for Growing Weed Indoors

After setting up a hydroponic system, it's also important for the plants to get nutrients, which in this case is done by adding nutrients to the water. These are known as hydroponic nutrients. 

Understanding the basics of hydroponic nutrients is the first step that someone who wants to grow cannabis should know of. 

Growing hydroponics is complicated, expensive, and time consuming, especially for a first time grower.  Get started growing your own Cannabis plant today with a Pot for Pot’s all natural soil based Complete Grow Kits!

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What Are Hydroponic Nutrients

nutrient rich soil

Hydroponic nutrients are the nutrients essential for a plant’s growth. These can be found in hydroponic kits for weed. Marijuana plants are just like any other plants and they too need proper nutrients to ensure a good harvest.

Essential Nutrients for Your Hydroponic System

When it comes time to choose the proper nutrients for your system, you must consider a few factors. You need to find nutrients that are made explicitly for your hydroponic system. Don't think you can use the same nutrients for those soil-based systems.

Along with that, choose nutrients that contain no organic matter. For example, your solution should not have nutrients that come from minerals. Instead, look for chelated mineral nutrients. What's that? These nutrients are easier for the plant to absorb in the water. You also want to use a high level of micronutrients that make up for the amount you would commonly find in the soil.

Those soil nutrients are not a great source of nutrition for your hydroponic plants. These nutrients are full of organic matter such as blood meal, worm castings, fish emulsions, and guano. You want an efficient system, and organic matter can introduce unwanted bacteria. There is one way to test whether the nutrients will work in your hydroponic system - if they make the water cloudy or float, you don't want to use them in your hydroponic system. 

Let's take a closer look at these vital nutrients.


Nitrogen is the building block of protein, and it is an essential part of every plant cell. The green pigment is what gives plants their green color, and it is the nutrient most responsible for photosynthesis.


Like nitrogen, phosphorus is another crucial element that transforms solar energy into chemical energy. It allows the oils, waxes, and plant sugars to develop into a distinct flavor for your marijuana. Plants need this nutrient to mature.


This nutrient is the final building block for your plant proteins. It can help with photosynthesis.

These nutrients are often not available as pure elements; instead, they are bound in compound molecules. With that, the plants can break them down, reducing the risk of toxicity.

A few other nutrients are essential to the hydroponic growing process, such as:


If you want a strong plant cell wall structure, you need calcium. This nutrient helps provide a normal transport and retention of other nutrients. It also works to help strengthen the plant.


This nutrient is another vital part of the chlorophyll cycle. It helps to keep your plants looking green and is an essential nutrient for photosynthesis. Magnesium can help to activate those plant enzymes that are required for growth.


There are so many functions that sulfur helps in the growing process. This nutrient can boost the production of vitamins, enzymes, and proteins. Along with that, it is a necessary element for seed production and root growth.

Trace Micronutrients and Elements

While those nutrients above are the "big" ones you need for healthy plants, you don't want to forget trace elements and micronutrients. These elements are not less essential than the significant nutrients. Your hydroponic plants will need minimal amounts to grow properly. You will need to add copper, zinc, iron, boron, molybdenum, manganese, and chloride to the water solutions. All of these substances can help with the growth or blooming stages.

Other Additives To Consider

Amino Acids and Vitamins

If you are searching for a nutrient solution for your hydroponic system, you probably have seen items with added amino acids and vitamins. In many cases, manufacturers will add these nutrients to the solutions. However, no research shows they can actually increase growth. You can experiment around with additional vitamins and amino acids, but that should be typically left in the hands of a professional.


In some circles, it has been recommended to use unsulfured blackstrap molasses as an additive to the growing system. This additive is less expensive than premade solutions, and it is also high in phosphorus, which helps during the flowering stage. Molasses has high levels of carbohydrates and iron. While there are a few benefits for soil-based systems, you never want to add molasses to your hydroponic system. You will be left with a potentially damaged growing system. 

Fulvic and Humic Acids

Fulvic acid is a subgroup of humic acid. It can help a collection of acids break down organic compounds. Fulvic acid also can help with the transposition of nutrients within your plant. It aids in the absorption of nutrients. Many of these acids do occur naturally in the soil, but there is still some debate about whether they help in a hydroponic system.

There are three essential hydroponic nutrients: Nitrogen, Phosphorous, and Potassium, also known as NPK. Other than these, there are other essential micronutrients and minerals like magnesium, calcium, iron, sulfur, boron, cobalt, copper, manganese, molybdenum, and zinc. All of these contribute to a good harvest. 

Hydroponic nutrients are solution-based and are administered to cannabis plants through the water. Administering hydroponic nutrients is about balance and science. In a hydroponic setup, one cannot just wing it. Since the purpose of growing weed or cannabis is usually commercial, there’s a huge financial investment involved.

Taking care of the weed plant is important and to do so one needs to have a clear understanding of the ratio in which the hydroponic nutrients are to be administered.

Understanding NPK Ratio

Obtaining the right balance is crucial for growth and achieving a good harvest. The label on hydroponic nutrients is written as N-P-K and can read 10-5-5 for example.  This indicates that the solution has 10% Nitrogen, 5% Phosphorous, and 5% Potassium. 

Each nutrient plays a different role. Nitrogen is important for the growth of a plant, phosphorous plays a crucial role as it encourages the growth of the roots and flowers, and potassium is responsible for the growth of roots and for photosynthesis.

Related: Growing Weed in Water Using Hydroponics

Measuring Your Nutrients

If you are serious about growing good-quality weed and don't want to worry about problems with your nutrient solution, it could be time to invest in a PPM meter. This device allows you to measure the Parts Per Million within your nutrient solutions. These nutrients include nitrogen, phosphorus, and potassium.

You can also monitor elements like calcium. If you want a high-quality product, you need to know these levels. With a PPM meter, you can gauge how many PPMs per each chemical is available in the solution. Too little or too much can disrupt the development of your plants from the seedling to the flowering phase.

You also need to monitor the nutrient levels if you use a particular type of growing medium. For example, coco coir is made from ground coconut husks. That is a natural material. Some of those raw materials can leach their other nutrients into the water. You will need to constantly monitor your nutrient levels to ensure that everything is in a safe range for your plants.

It might not be a bad idea to purchase a pH level meter as well. This device works differently than a PPM meter as it measures the acidity of the plant food. You can also use it to measure the water's acidity levels. For the best results, measure the water by itself and then measure water with the nutrients. With that, you can tell whether your plants are getting the right amount of nutrients for growth and development. When your water level is well-balanced, then you can expect a great grow.  

Different Stages Of Growth

stages of cannabis growth

There are two main stages of cannabis growth, vegetative and flowering. Both of these stages require different NPK ratios. 

The vegetative stage requires high nitrogen, medium to high phosphorus, and high potassium. While the flowering stage requires low nitrogen, high phosphorus, and high potassium. 

Adding too much nitrogen affects the development of buds and is also responsible for giving them a strange taste. When the plant starts to enter the flowering stage, that’s when the buds start to form.

Potassium adds weight to the buds while phosphorus is responsible for increasing the number of flowers in the plant. 

Hence, it’s important to monitor the growth of the plant and administer hydroponic nutrients accordingly.

If not done correctly, the plants will either not yield a good harvest, or end up dying. Because of this, it’s crucial to give them proper hydroponic nutrients while taking care of their needs at different stages.

Related Article: How Much Weed Does One Plant Produce?

Soil and Hydroponic Nutrients

Hydroponic nutrients are vastly different from soil nutrients and they can’t be used interchangeably. Soil nutrients are made up of organic solids that will clog a hydroponic system. 

In a soil-based system, these solids are broken down by the soil and nutrients are provided to the plants, whereas in a hydroponic system, nutrients and micronutrients have to be fed directly to the plants. 

Other than that, soil nutrients have high amounts of phosphorus and low nitrogen which definitely aren’t suitable when it comes to growing cannabis in a hydroponic setup.

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In Conclusion

cannabis grown with hydroponic nutrients

Understanding and using hydroponic nutrients correctly can make all the difference in the type of yield one receives. The more care and attention one provides to these plants, the better the harvest.  It's as simple as that. That's why it is crucial to understand the basics of hydroponic nutrients. 

After following the basic principles outlined above, not only will the harvest be better, the approach to hydroponics will be more systematic and less trial-and-error. 

However, growing with hydroponics is still a complicated and costly process, with many things that can go wrong and ruin a harvest.  That's why we recommend natural soil growing, especially for first time growers.

Check out a Pot for Pot’s all natural soil complete grow kits to get started growing your own cannabis plants today!

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