Understanding Hydroponic Nutrients for Cannabis 

So, you're ready to take the plunge into hydroponics? Awesome! Growing without soil opens up a whole new world of possibilities. In hydro, you're not just growing plants but engineering their environment. 

You have the power to control everything from temperature and humidity to how much light they get. Let's not forget, you also have control over what they eat, i.e., the nutrients. The same can't be said about soil-based cannabis, right? 

That said, using nutrients for hydroponics can be tricky. But don't worry, we've got your back. In this article, you'll learn about hydroponic nutrients, from the basics of N-P-K to the differences between synthetic and organic options. So, let's start. 

What Are Hydroponic Nutrients?

If you're ready to ditch the soil and move to hydroponics, you need to start focusing on nutrients. Growing plants without soil gives you a new level of control, yes, but it also means you are completely responsible for feeding your plants. 

Think of it this way: in soil, your plants are like backyard chickens, happily scratching around for their own food. In hydroponics, you are the farmer, providing a perfectly balanced and nutritious meal every single day.

The key to success in hydroponics is understanding plant nutrition. Instead of relying on the natural nutrients provided by soil, you will be supplying a precisely formulated liquid diet.

The NPK Ratio

Cannabis depends heavily on macronutrients like nitrogen (N), phosphorus (P), and potassium (K) but you also can't ignore the importance of micronutrients — we will discuss this later. As the name implies, plants need macronutrients in large amounts compared to micronutrients. 

 

First, you need to consider the macronutrients: nitrogen (N), phosphorus (P), and potassium (K). These three are the foundation of any healthy plant diet.

• Nitrogen

Think of nitrogen as your plant's muscle builder. They make your plant's leaves stronger. And strong, vibrant leaves lead to increased photosynthesis, which results in bigger, fatter buds. It also helps in making proteins, enzymes, and new tissues.

This is why when your plants are nitrogen-deficient, you'll notice that older leaves start to yellow and droop — definitely not a good sign.

Signs of Deficiency:

• Older leaves turn yellow from the bottom to the top of the plant.
• Growth slows down and leaves will shrivell. 

Signs of Excess:

• The leaves are dark green and waxy.
• The stems become weak and vulnerable to pests. 
• Delayed flowering.

Sources of Nitrogen:

Ammonium nitrate, calcium nitrate, urea.

• Phosphorus

Phosphorus is crucial for strong root growth, stems, and, most importantly, the development of those frosty buds we all crave. During the flowering stage, your plants will need a lot of phosphorus. So, don't skimp on this nutrient, or you may end up with a disappointing harvest.

Plants need inorganic phosphate for transferring energy and ATP (adenosine triphosphate) formation. It also aids root growth, flower development, and seed creation.

Signs of Deficiency:

• The veins in the stems and leaves turn purple or reddish in color. 
• Lack of development and sluggish growth.
• Weak flowering and bud creation.

Signs of Excess:

• Plants cannot absorb certain nutrients properly.  
• There's a decline in growth, and the plants don't grow as fast as you expect either. 

Sources:

MKP or monopotassium phosphate, ammonium phosphate, and rock phosphate. 

• Potassium

While not as crucial as nitrogen or phosphorus, potassium is still a vital nutrient. It strengthens stems, boosts root development, and helps ensure that your plants produce sweet, resinous buds. It also regulates water flow in plant cells and improves drought resistance and nutrient transport.

Signs of Deficiency:

• Leaves are turning yellow or brown at the edges and tips.
• The plant's weak stems are also unable to resist stress. 
• Poor bud formation.

Signs of Excess:

• Calcium and magnesium deficiencies occur because of antagonism.
• Leaf curling and tip damage. 

Sources:

Potassium nitrate/sulfate/chloride

The Micronutrients  

But wait, there's more! Just like humans need a balanced diet, your cannabis plants require a variety of micronutrients to thrive. This includes essential elements like magnesium, calcium, iron, and sulfur — crucial nutrients that help your plants stay healthy and strong. 

Don't forget about the trace elements, too — boron, cobalt, copper, and others. Although they play smaller roles, they are still essential for overall plant health.

Balancing NPK Ratios

Cannabis requires the best NPK ratio throughout its growth cycle. First, you have the seedling stage where they are super delicate, so they only need low concentrations of nutrients in the medium, especially nitrogen. In fact, it's best not to feed anything at all during the first week. After that, you can use a gentle 2-1-2 ratio or use a fertilizer meant for cannabis seedlings. 

In the vegetative stage, the plants will be big enough to absorb more nutrients, so you can feed fertilizers high in nitrogen or use the “Grow” part of your 3-part fertilizer if you have it. The NPK ratios differ widely, making it slightly confusing, but remember to look for high nitrogen content. For example, 4-2-3 or 3-1-2 would work. 

Coming to the flowering stage, you'll need to increase phosphorus and potassium for bud formation and resin production. It is better to use a 1-4-5 ratio or 2-4-6 ratio. In the late flowering stage, cut nitrogen even further and increase potassium to help the plant ramp up bud production. 

Tips to Manage NPK Levels in Hydroponics

• Use EC or PPM meters to test the nutrient solution's strength frequently.
• Don't overfeed because the nutrients fed via the hydroponic system get to the roots without buffering.
• Keep an eye on the plant's health and adjust the NPK based on the growth stage and plant. 
• Every so often, flush the system to reduce nutrients from building up as they eventually cause a lock-out.

How Are Hydro Nutrients Different from Soil Nutrients?

Hydroponics is a whole different ball game than growing cannabis in soil. In soil, cannabis plants operate like backyard chickens, happily foraging for their own food as they interact with the earth and find the nutrients they need. 

In hydroponics, you're responsible for feeding your plant. You have complete control over your plant's menu, which is exciting but also comes with a bit of a learning curve. 

The Main Difference

One of the great things about soil is that it is a living ecosystem filled with beneficial microbes that break down organic matter — like manure, worm castings, and other nutrients — into forms that plants can readily use. 

In hydroponics, however, the environment is more sterile. You bypass much of that natural microbial activity, which means you must provide your plants with a complete and balanced diet, including all the essential micronutrients they usually get from the soil. 

For instance, soil typically contains a good supply of micronutrients, such as iron, copper, and magnesium. In a hydroponic system, you need to ensure that your nutrient solution is rich with these essential elements.

Nitrogen is another key difference. Soil usually has a decent amount of nitrogen, which is why many soil-based fertilizers emphasize phosphorus and potassium during the flowering stage. In hydroponics, you often need to provide a heavier dose of nitrogen during the vegetative stage to support vigorous leafy growth.

So, growing cannabis hydroponically requires a deeper understanding of plant nutrition. You aren't just providing water; you're creating a perfectly balanced liquid diet that meets all of your plants' needs. 

Types of Hydroponic Nutrients

Let's dive into the essentials of feeding your hydroponic plants. Choosing the right nutrients is crucial as it can significantly impact your growth results. Let's take a look at different types of hydroponic nutrients. 

1. Premixed vs DIY

You can grow cannabis using commercial nutrients or make it from scratch at home. It will all boil down to your goals, budget, and how many plants you want to grow. 

Commercial Nutrients

Pre-mixed nutrient solutions or commercial ones are ready-made products designed for convenience. These products come in either liquid or powder form and are nutritionally balanced, containing the right amount of macronutrients, secondary nutrients, and micronutrients.

Advantages

• Convenience

The best part of using commercial nutrients is that you don't have to source anything or work out any calculations, which is great for new growers and even seasoned growers who don't want the added headache. 

• Consistency

Using commercial nutrients helps you achieve a consistency that's very difficult to achieve with DIY nutrients. Apart from that, these nutrients supply everything the plant needs at every stage of growth and lower the chances of mistakes that can result in deficiencies or toxicities.

• Wide Availability

You can find them at most gardening or hydroponic stores, regardless of where you live. 

Disadvantages

• Higher Cost

Usually pricier than doing it yourself, particularly for big grows. However, for small setups, this is the best option as you can only save money if you're buying nutrients in bulk when you're making them from scratch. 

• Limited Customization

Pre-mixed solutions may not allow you to make adjustments for your own specific strains and growing conditions.

Best For:

• Beginners and hobbyists who don't want to spend too much time formulating nutrients. 
• Those growing a few plants and want simplicity.

DIY Nutrient Solutions

You can mix individual nutrient salts to make your own nutrient formula. However, to do this, you'll need to be knowledgeable of the plant's nutrient requirements and also possess good measuring and mixing abilities.

Advantages

• Cost-Effective

Nutrient salts are often cheaper in bulk, making nutrient solutions more economical for larger grows.

• Customization

This helps you modify nutrient formulations exactly to suit specific growth stages or special plant requirements.

• Control Over Ingredients

Growers can make sure to use good quality ingredients and avoid unwanted ones. 

Disadvantages

• Complexity

Must know how to analyze the nutrient demands of plants and measure and mix accurately. Any errors can cause deficiencies or toxicities by skewed solutions. 

• Time-Consuming

Since you have to carefully prepare your own solutions, they will take more time and effort. 

• Potential for Errors

When you measure wrong or mix incorrectly, it won't work effectively.

Best For: 

• People who already grow cannabis or other plants hydroponically or are knowledgeable about hydroponics.
• Those who want to reduce costs through large-scale operations.
• Farmers trying new types of nutrients or organic.

2. Synthetic vs. Organic: The Great Nutrient Debate

In the world of hydroponic nutrients, there are two primary categories: synthetic and organic.

Synthetic Nutrients are lab-produced formulations containing specific amounts of each nutrient, making them easy to measure and control. They are the efficient and straightforward option, and they are generally more affordable and readily available, too. 

Organic Nutrients, on the other hand, come from natural sources such as seaweed, kelp, and bat guano. These nutrients are rich in beneficial microbes and various compounds that can enhance flavor and aroma and even boost terpene production. 

Many growers prefer organic nutrients because they believe they produce buds with richer flavors and aromas. Moreover, if you're aiming for a more eco-friendly and sustainable approach, organic options may be the way to go. 

However, it's essential to note that organic nutrients often come with a higher price tag due to their production methods and ingredients. Meanwhile, synthetic nutrients provide a consistent and reliable supply, making it easier to establish your feeding schedule; they typically require no complex mixing or adjustments.

3. Liquid vs. Powder: A Matter of Convenience 

Next, let's discuss the delivery system: liquid versus powder nutrients. Liquid Nutrients are ready to use — just add them to your reservoir, and you're set! They are highly convenient, but storage is crucial to prevent spoilage.

Powdered nutrients require a bit more preparation: you need to mix them with water before adding them to your system. However, they offer greater flexibility and can be more cost-effective in the long run. They are also more concentrated, requiring less storage space.

4. Single-Part vs. Multi-Part: Finding the Right Formula

Finally, there's the choice between single-part and multi-part nutrients. Single-part nutrients provide an all-in-one solution, making them very simple to use. Just add and grow your cannabis.

Multi-part nutrients, however, function like a nutrient buffet, providing separate bottles containing different nutrient groups. This format allows you to have greater control over your nutrient mix, allowing you to fine-tune your feeding schedule according to your cannabis plant's needs.

Ultimately, choosing the proper nutrients for your hydroponic cannabis garden is a personal decision. There's no one-size-fits-all answer. Experiment with different options, observe what works best for your plants, and enjoy the journey!

Don't Forget the pH 

When giving your hydroponic cannabis the right nutrients, you need to also focus on the pH. It is one of the most important environmental factors that affects how your plant consumes its food. 

Think of pH as the key that unlocks your plants' ability to absorb nutrients. Just like humans need the right conditions to digest food, your plants require an optimal pH environment to absorb the nutrients you're providing properly. 

The pH scale measures how acidic or alkaline a solution is. For cannabis plants, the ideal pH range for nutrient absorption is generally between 5.5 and 6.5, with 5.7 being the sweet spot. 

In addition, you can adjust the pH according to the growing stage of the plants if you can. 

Seedling stage - 5.5 to 5.8 for root growth and nutrient uptake.

Vegetative Stage: 5.8 to 6.0 to utilize nitrogen for growing leaves.

Flowering Stage: 6.0 to 6.2 for easier bud development, phosphorus, and potassium availability is important.

If the pH level is off, your plants may struggle to absorb essential nutrients, even if you're giving them the best food. This can lead to nutrient deficiencies, often visible as leaf discoloration. Yellowing leaves can be a sign that something is wrong — either your plants aren't getting enough nutrients, or they simply can't absorb what you're providing. 

Remember, maintaining the correct pH is an ongoing process. Don't rely solely on pH-stabilizing solutions. While these products can be helpful, they shouldn't be your primary defense.

Having said that, a better approach is to flush your system if you overfeed the plants unintentionally. Flushing helps remove nutrient buildup and stabilize pH levels. Also, invest in a pH meter — they are easy to use and give you an accurate reading quickly. 

Monitoring and adjusting pH is a critical part of any successful hydroponic grow. By maintaining the optimal pH range, you're ensuring your cannabis plants can make the most of the nutrients you're providing, which leads to healthier plants and bigger, better buds.

Effects of pH imbalances on Nutrient Uptake

So, what happens if you don't take care of the pH levels properly? Here are a few things to watch out for:

Low pH acidic Condition (<5.5)

• Can cause toxicities of micronutrients, including iron and manganese.
• Limits the availability of calcium, magnesium, and phosphorus, causing deficiencies.
• Leaves turn yellow, no plant growth and the roots get damaged. 

High or Alkaline pH

• Decreases the solubility of important nutrients such as iron, zinc, and manganese.
• Nutrients in the solution do not work due to nutrient lockout in plants.
• Symptoms include interveinal yellowing, stunted growth, and weak buds. 

If you don't handle the imbalance immediately, it can compound the deficiencies and also make the plants vulnerable to diseases and pests.

So, now you know that it's important to measure and adjust the pH as necessary. To do so, you can use digital pH meters that are very accurate and easy to use. However, make sure you calibrate them frequently with buffer solutions so they continue to work correctly. 

Some growers use test strips to check the pH but it's not accurate. A digital pH tester may cost more but it's well worth the extra cost. 

To adjust the pH, you can use pH Up or pH Down to increase or decrease the pH as the name implies. If you can't find them, remember that while potassium hydroxide (KOH) is used to raise the pH of acidic nutrient solutions, pH Down usually contains phosphoric acid or nitric acid used to decrease the pH level of alkaline solutions.

But, if you're a beginner, you're probably wondering how to actually change the pH. Well, first, you check the pH of the solution. 

Next, add pH Up or Down as necessary. Remember to start with just a few drops as these chemicals are pretty strong and can change the pH rapidly. Mix the solution vigorously after you add a few drops and test the pH again. Let the solution rest for about 20 minutes and you can use it if the pH has stopped fluctuating. 

Tips to Manage pH consistently

• Allow water to dechlorinate for 24 hours and reach room temperature before adjusting the pH if you're using tap water. 
• Test the pH of the water daily, so you can catch issues sooner. If not, do it at least 2-3 times a week. 
• Make a record of adjustments to understand how to work with the solutions easily. 
• Invest in good nutrient solutions as they are often pH-buffered to prevent fluctuations.

EC and PPM

Nutrient strength is very important in hydroponics as the plants will rely on the nutrient solution for their food. Electrical Conductivity (EC) and Parts Per Million (PPM) are the main measurements used to measure and modify nutrients. In this section, we will discuss what these metrics are, why they are important, and how to manage them. 

What is Electric Conductivity (EC)?

EC shows how well a nutrient solution can conduct electricity. The more dissolved salts (nutrients), the more the electrical conductivity. It is measured in millisiemens per centimeter (mS/cm) or microsiemens (µS/cm).

What Does PPM Mean? 

PPM evaluates the amount of solids (nutrients) dissolved in the solution. Typically, it is calculated by using a conversion factor that is applied to the EC. 

Ultimately, EC and PPM refer to the same thing (nutrient concentration) — just different ways of saying it! However, EC is preferred as PPM relies on conversion factors.

Ideal Levels of the EC/ PPM

Cannabis plants need different nutrient strengths depending on their stage of growth. If the levels are overly high or low, it could cause deficiencies, toxicities, or nutrient burn.

Stage of Growth	EC	PPM (500 scale)	PPM (700 Scale)
Seedling	0.4-0.6	200-300	280-420
Early Vegetative	0.8-1.0	400-500	560-700
Late Vegetative	1.2-1.6	600-800	840-1120
Early Flowering	1.6-2.0	800-1000	1120-1400
Late Flowering	1.8-2.2	900-1100	1260-1540

Considerations for EC/PPM Levels

• The starting EC of the tap water determines the final reading.
• Different strains need slightly different nutrients, although the changes won't be too much. 
• If the light intensity of a plant is high or if carbon dioxide is supplemented, then higher nutrient strength may be required.

Adjusting EC/PPM For Hydroponic Cannabis

You must measure the EC/PPM accurately when growing cannabis hydroponically as it allows you to provide plants with the right nutrient concentration. EC and PPM values tell you how strong the nutrient solution is to avoid under or overfeeding. Here's a thorough breakdown of measuring EC/PPM to give your plants the perfect feed.

Why Should You Use an EC/PPM Meter?

Having a dependable EC/PPM meter is important for many growers. Rather than going for a cheap one, make sure you get a good device even if it means that you have to spend a little extra. Also, you want something that lasts for a long time while providing accurate readings all the time. It's a matter of life and death for your plants, so don't ignore this. 

Steps for Measuring EC/PPM

1. First, make sure your EC/PPM meter is calibrated correctly. Many meters require calibration using a specific solution (1413 µS/cm for EC meters, for example). Follow the manufacturer's instructions for proper calibration.
2. Before using the probe, you should rinse it with distilled water to eliminate any contamination. Naturally, rinse it after using it too. However, try and avoid tap water as it can sometimes contaminate your probe. 
3. Next, place the probe inside the reservoir or a sample of the nutrient solution. Make sure it is totally submerged for proper reading. Carefully stir the solution to ensure no air bubbles stick to the probe, they will change readings.
4. Now, wait for a few seconds for the meter to stabilize. Some advanced meters have a stability indicator that indicates when the reading is stable and final. It's okay if you don't have this too as you simply need to wait for a few more seconds. 
5. To increase the nutrient strength, gradually add a more concentrated nutrient solution. Stir well and measure again to avoid overshooting. Conversely, to decrease the nutrient strength, add more pH-balanced water to dilute the solution. Stir thoroughly and double-check the EC/PPM. If your levels are too high and causing nutrient burn, flush your system with pH-balanced water and make a new one.
6. To avoid confusion, record the EC or PPM value for your nutrient solution. Check the reading against the recommended levels for your plant's stage of growth.
7. Once you're done using it, rinse the probe off with distilled water a second time and wipe dry with a clean, lint-free cloth.

Additional Tips:

1. Check Solution Temperature

Your nutrient solution's temperature influences the conductivity. Most good meters come with automatic temperature compensation (ATC), but if you have one without it, make your reading at the same temperature (about 68°F or 20°C).

2. Regular Calibration

While it may seem silly, regular calibration is crucial as it keeps the readings accurate over time.

3. Avoid Contamination

Never dip a dirty probe into your reservoir as this will contaminate your nutrient solution and readings.

4. Use Clean Sampling Containers

When measuring a sample outside of the reservoir, make sure the container is clean and has no residue in it.

If you follow the steps above, you will ensure that your cannabis plants receive the right nutrient concentrations through EC and PPM measurements. To be successful at hydroponics, you must frequently and accurately measure your EC or PPM values. 

Common Problems with Hydroponic Nutrients

Even in a water-controlled hydroponics system, one can face problems with nutrient management which can be the reason behind your plant's unproductivity. Learn more about how to identify and prevent the problems that affect cannabis such as overfeeding, deficiencies, toxicities, and nutrient lockout.

1. Overfeeding and Nutrient Burn

When nutrient concentration is too high, it causes nutrient burn. Typically, this happens when there are excessive salts that damage the plant — a result of overfeeding your plant. 

As a result, you might notice some symptoms including browning or burnt leaf tips. The edges of the leaves may look crispy and curl as well. Overall, the growth may be stunted, and you may also see yellowing between veins (chlorosis).

Causes

• An overly concentrated nutrient solution
• You're not checking the EC/PPM levels regularly

Prevention and Fixes

• Mix nutrients as per the manufacturer's guidelines.
• Check the EC/PPM levels on a regular basis.
• Slowly raise nutrient strength as plants grow more.
• Use plain, pH-balanced water to flush the system off excess nutrients. 
• Give a weaker nutrient solution again and see if plants get better.

2. Deficiencies and Toxicities

Cannabis plants need a specific set of nutrients. Not enough or too much of a nutrient will cause poor growth and reduced yields. Here are a few common deficiencies and symptoms:

• Nitrogen (N): Older leaves turn yellow and growth is poor.
• Phosphorus (P): Purple stems, slow growth, and dark leaves. 
• Potassium (K): Spotting on leaves, and stems become weak.
• Calcium (Ca): Leaves curling, brown spots, distortion with calcium.
• Magnesium (Mg): Yellowing that starts on older leaves between veins. 
• Iron (Fe): New growth is yellowing while veins remain green. 

Toxicity Symptoms

• Nitrogen: It can inhibit flowering by stimulating leafy vegetation growth.
• Phosphorus: Can cause iron and zinc deficiencies. 
• Potassium: Calcium and magnesium lockout.

Prevention and Fixes

• Use balanced nutrient solutions intended for cannabis.
• Change nutrients based on the crop's growth stage.
• Test EC/PPM and pH levels often.
• Find deficiency or excess according to symptoms.
• Change the nutrient solution to correct the unbalanced element.

If toxicity is severe, flush the system and slowly reintroduce nutrients.

3. Nutrient Lockouts

Nutrient lockout happens when there are nutrients available, but the plants cannot uptake them because of imbalanced pH or excess salts.

Causes

• Incorrect pH levels
• A salt build-up in the growing medium or nutrient reservoir
• Excessive nutrient concentrations

Symptoms

• Even with enough nutrients in the solution, symptoms often mimic deficiencies.
• Discoloration, stunted growth, yellowing leaves.

Prevention and Fixes

• Keep the pH within the appropriate range (5.5-6.5)
• Flush the system to prevent salt build-up
• Stop overfeeding nutrients
• Flush the system to remove salt build-up and reintroduce nutrients slowly. Monitor the plants like a hawk and look for improvement in a few days. 

4. Maintaining a Feeding Schedule

A good feeding schedule allows you to provide the right dose of nutrients at the right time which is what helps your cannabis plant reach its full potential. This is very important as it prevents nutrient imbalances, helps the plant develop in a healthy manner, and also caters to its needs at different stages of growth (as long as you use the right nutrients according to the stages of growth). 

If you're unsure about this, you can also set up a timer that reminds you to feed the plants. Some growers prefer automatic delivery, but such systems can be expensive, especially if you just want to feed just a few plants. 

5. Reservoir Maintenance

The heart of your hydroponic system is your nutrient reservoir. If you want to avoid issues with nutrients, it's best to keep it clean. 

Also, remember that regularly maintaining your reservoir will stop nutrient imbalances, lessen the chance of algae development and root rot, and aid in the efficient absorption of nutrients. 

Here are a few tips to help maintain your reservoir: 

• You must clean your nutrient reservoirs regularly to prevent algae, mold, or bacteria build-up.
• Make sure you change the nutrient solution every few weeks or there can be an imbalance, and the solution may stagnate.
• Add more pH-balanced water if the solution evaporates. Do not add more concentrated nutrients. Instead, top off with clean water. 
• Keep an eye on the temperature of the water in your reservoir. Bacteria will rapidly grow when the temps exceed 75°F (24°C), causing havoc on your nutrient solution.
• Using a reservoir cover will keep light out which will stop algae or fungal growth from forming.

So, there you go! You now know a lot more about using hydroponic nutrients for cannabis and can do it with more confidence than ever. 

Summary: Understanding Hydroponic Nutrients for Cannabis 

Mastering hydroponic nutrition is an ongoing learning process. It requires a keen eye, careful observation, and a willingness to experiment. Don't be afraid to adjust your nutrient regimen as your plants progress through different stages of growth.

Remember, the goal is to create a thriving environment where your cannabis plants can reach their full potential. By understanding the unique needs of your plants, choosing the right nutrients, and maintaining the optimal pH, you'll be well on your way to producing high-quality, bountiful harvests.