hydroponics weed nutrients

A Guide On Cannabis Nutrients For Hydroponic Systems

Are you sure you’re using the correct products for your hydroponic system? These will differ quite significantly from soil solutions. Make sure you know what to use, and in which quantities.


When growing without soil, nutrients will be a crucial factor to consider when trying to achieve the best yields possible. With the right combination, you’ll be sure to get the best buds in terms of quantity and quality.

In hydroponic systems, the nutrient solution you choose will replace the micro and macronutrients that soil would normally provide. The advantage of hydroponic growing, however, is that you can replicate a soil medium without the unpredictability.

The first thing you should look for when purchasing nutrients is the ratio of three essential nutrients: nitrogen, phosphorus, and potassium (N-P-K). These are the macronutrients. They are called this because they are absorbed in the largest quantities by the plant.

Nitrogen is responsible for leaf growth and pigmentation. When there is a lack of nitrogen, older leaves turn yellow and soft. This can lead to a lethal condition if not fixed in a timely fashion. Phosphorus is what you’ll need for the proper development of stems, roots, and flowers. Because of this, during the flowering stage, your plants will require more phosphorus to produce bountiful yields. A phosphorus deficiency during the flowering stage can affect the quantity and quality of your buds drastically, so be careful. Potassium is of slightly lesser importance, but still contributes to the development of the buds, stems, and roots. It also ensures that proteins are synthesised.


With so many brands and combinations of nutrients out there, which one is best for your grow? This is an important decision, but one you’ll be learning more and more about as you go. Only experience will help you assess the correct nutrients for your situation. It all depends on what you’re trying to achieve. But here are a few pointers to get you started.

Make sure that the bottles contain no organic matter; this will cause root problems and spur the formation of bacteria. The minerals you use should be chelated. This is when nutrients are covered by an organic molecule that is less sensitive to pH changes. This gives the plant a wider pH range in which it can properly absorb nutrients. And finally, the ideal NPK ratio will also be crucial.

NPK will be displayed on nutrient bottles as a ratio of 3 digits, each describing the percentage of the corresponding nutrient. The remaining percentage will be composed of micronutrients. The ratio of nutrients will change depending on the stage of growth. During the vegetative stage, your nitrogen value should be high, phosphorus should be medium-high, and your potassium, high too. When you move into flowering, make sure you decrease the nitrogen percentage. This should be kept low while the other two remain high.


There are some nutrients that are more easily absorbed by cannabis roots than others. Independently of the nutrient brand you choose, your plants can still face deficiencies if the pH is not correct.

Cannabis plants function improperly when the pH around the root zone moves into an undesirable range. This is why you need to be ready to act when you spot a deficiency. These tend to first show in the colour of the leaves. When they turn yellow, either you’re lacking nutrients, or the plant isn’t able to absorb the essentials it needs.

In hydroponic systems, nutrients tend to be better absorbed when the pH around the root zone is between 5.5-6.5. But the ideal value you should aim for is 5.7. When looking to dial-in your pH, don’t necessarily trust a pH-stabilising solution. This kind of product still requires your constant attention. You’ll be better off flushing your system every now and then before purchasing pH-adjusting products.


With hydroponic systems comes the obvious advantage of having more control over what the plant is absorbing. Having constant access to water and oxygen, you just have to control which nutrients you give your plants, and in what amounts. But using this more experimental system can also detract from some of the beauty of growing weed in a traditional way.

In a soil medium, manure can be added, which is a nutrient-rich material that will certainly improve the general health of your plant. This is something that a nutrient solution can’t replicate. Soil contains microbes that help turn organic material like guano, worm castings, etc. into usable nutrients for your plants. But in hydroponics, it is necessary to feed your plants the micro and macronutrients directly. Independently of the quality of your soil, you’ll always be needing extra supplements to obtain the best results. This is where hydroponic systems most differ from soil-based mediums.

Micronutrients like iron, copper, and magnesium are widely available in most soil mediums. Therefore, hydro solutions must contain more of these to compensate. Soil also contains more nitrogen. This is why hydro nutrients receive a hefty dose of nitrogen in the vegetative stage.


The debate between growing in soil vs using a hydroponic system continues to unfold. We assume you’ve already made the difficult choice and are ready to commit to your method. Once the commitment is established, you’ll have to make the decision of purchasing the best products for your situation. These will depend on personal preference, level of experience, and commitment to the grow operation. You might prefer nutrient solutions that require less attention, or you might be looking to control every single factor that can influence your yields.

These are all decisions you’ll have to make on your own, independently of what you read. No matter your level of experience, you’ll always run into problems that will likely require your intervention. This is how you learn. Just don’t let the death of a plant demotivate you or stop you from trying again. Hydroponic systems have the potential of yielding ridiculously potent, high-quality buds. The effort will pay off.

Good luck with your system and just remember that attention is key. As long as you’re confident in reading your plant’s signals, you shouldn’t worry. Have a good harvest.

Learn more about what to look for when purchasing nutrients for your hydro system and how these differ from a soil medium.

Best Hydroponic Nutrients for Cannabis?

In other words, why are some hydro nutrients better than others for growing cannabis? What kind of hydroponic nutrients need to be avoided when growing marijuana? Do you need expensive nutrients to get good results, or will cheap nutrients get the job done?

With all the different bottles of marijuana nutrients out there, how do you know which one is best for your hydroponic setup?

When it comes to choosing hydroponic nutrients for growing weed, there are a few considerations that are really important!

Best Hydroponic Nutrients

  • Made specifically for hydroponics
  • No organic matter (nutrients are provided via minerals)
  • Mineral nutrients are “chelated” (easier for plant to absorb at a greater range of pH levels)
  • Contains rich sources of micro-nutrients (to make up for what might have been found in the soil)
  • Optimum NPK ratios (more info below)

Worst Hydroponic Nutrients

  • Made specifically for soil
  • Contains a lot of organic matter (guano, worm castings, fish emulsion, blood meal, etc) – this stuff can completely mess up your reservoir and cause unexpected and unwanted bacteria/root problems. If it seems cloudy with lots of material floating in the water, don’t use it for hydro!

You can learn a lot about nutrients by looking at the label!

Optimum NPK Ratios for Hydroponic Cannabis Nutrients

N-P-K stands for Nitrogen-Phosphorus-Potassium, which are the three most important plant nutrients. These are what the 3 numbers listed on the front of all nutrient bottles stand for (Potassium is represented by “K” because chemists use the symbol K in the periodic table for potassium).

In order to get the best results growing cannabis in hydroponics, it’s important to give the right ratio of these crucial nutrients so the plant gets what it needs at the right time. For example, if you give too much Nitrogen in the flowering/budding phase, it actually surpresses bud production and reduces your yields even if the plant is completely healthy! You don’t want that!

So what are the optimum NPK values for growing cannabis in hydro?
(N-P-K are the 3 numbers on the front of nutrient bottles)

Optimal Hydroponic Cannabis N-P-K Nutrient Ratios
Life Stage N P K
Vegetative/Grow High Medium to High High
Flowering/Bloom Low High High

Additionally, hydroponic nutrients should always include….

  • Magnesium
  • Calcium
  • Iron
  • Sulfur

Nice but not necessary micro-nutrients (contained in most water sources, but if using RO or very soft water you want these in your nutrients to prevent possible deficiencies)

  • Boron
  • Cobalt
  • Copper
  • Manganese
  • Molybdenum
  • Zinc

The main difference between NPK ratios for hydro and soil are….

  • Hydro nutrients usually contain more micro-nutrients (in trace amounts), to make up for what the plant would have been able to find in the soil
  • Hydro nutrients tend to contain higher levels of Nitrogen, which is abundant in soil but not in most water sources.
  • Hydro nutrients tend to have lower levels of Phosphorus, because Phosphorus is more “available” to the plant in a hydroponic setting. In soil, there are microorganisms (as well as clay “colloidal” particles) which can ‘steal’ some of it, and soil nutrients compensate by adding more Phosphorus.
  • Hydro nutrients rarely use organic sources of nutrients. Soil nutrients often contain organic material, which can can make it easier for bad stuff to grow in a hydroponic reservoir. Organic sources of minerals also usually need to be broken down by microorganisms before the plant can absorb them, which doesn’t happen as well in a soilless environment.
  • Hydro nutrients are often made up of chelated minerals which have been specially treated so they are easier for the plant to absorb.

What are Chelated Nutrients? Manufacturers actually “wrap” the nutrients inside an organic molecule that is less affected by pH, making it easier for the plant to absorb even if the pH is too high or too low.

When set up right with good nutrients, DWC / Hydroponics can produce some incredible yields!

Optimum pH of 5.5-6.5 Recommended DWC Nutrients & Supplements

These hydroponic nutrients systems are not just great as far as cannabis yields and quality, they won’t break the bank either! There are lots of great nutrient systems out there, but the truth is that you don’t need incredibly expensive nutrients to get incredible marijuana!

The following nutrient systems have proven to thousands of growers, big and small, that they have everything needed to produce star-quality cannabis!

General Hydroponics Flora Trio Lineup

These plants grown using just the GH Trio + Hydroguard (formally known as Aquashield)
Feel free to check out the complete grow journal (over 1 lb harvest!)

General Hydroponics Flora Duo Lineup

General Hydroponics FloraDuo (Bottle A & Bottle B) ​

Hydroguard (formally known as Aquashield) – prevents and treats root rot.

House & Garden DWC Kit Lineup

Warning: H&G Products have been difficult to find online lately

The House & Garden line-up is expensive yet remarkably effective. Aqua Flakes A + B, Roots Excelurator, Algen Extract ​

Hydroguard (formally known as Aquashield) – prevents and treats root rot. No need for extra Cal-Mag with the Aqua Flakes line as it already comes with plenty!

Botanicare KIND Hydro Lineup

This is actually the hydroponic nutrient lineup I plan to use for my next grow. Right now I’m using the General Hydroponics Flora trio (which I’ve used for more than half a decade with amazing results), but I’ve decided I want to try something new and KIND is what I’ve decided to go with. I’ve heard/seen so many great things about it and Botanicare is a great company that takes feedback from cannabis growers and is happy to answer any questions if you contact them through their website.

Botanicare KIND Trio For Hydro (Base, Grow, Bloom) ​

From a grower who wrote in: “I use the Botanicare KIND lineup – it seems to get good results, not too expensive, and works very well in hydro.” Another grower told us, “As far as favorites go, I’ve been pretty pleased with Botanicare KIND, it’s ‘pretty good’ when you follow the chart, but once you start tinkering with it based on what you see with your plants, it’ll really shine since it was developed to be played with.” Apparently a lot of growers like tinkering with this trio as another grower said, “Botanicare KIND is like the opposite spectrum [of the Botanicare Pure Blend series]. The Base is just Nitrogen and Calcium. Grow and Bloom both have most of the minerals in them, along with things like seakelp! The Bloom is also 0-6-6. Grow at 2-2-4. So quite literally you can call the shots on Nitrogen and Calcium. That level of control hasn’t been around a great deal in our market. For the savvy grower this is a pretty nice tool.”

If you think you have the best hydroponic cannabis nutrients, tell us about your results!

Ever wondered what makes hydroponic nutrients "good" or "bad" for cannabis? Learn about the different types of ingredients that go into hydroponic nutrients to learn which ones work great for marijuana, and which ones to avoid!