9 Mistakes To Avoid When Growing Hydroponic Cannabis

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Added 16 November 2021

Growing cannabis using a hydroponics system can be an exciting hobby project, but going about it the wrong way can result in unsatisfactory yield (and loss of money). 

And while there are hundreds of articles on the internet doling out advice on growing hydroponic cannabis, there’s still a lot of room for errors that can impact your cannabis growth.

Now, if you want the best results, you must pay heed to the process and avoid errors as much as possible. 

But what are these mistakes? 

In this article, we will explore nine mistakes most new hydroponic cannabis growers make and how to avoid them.

1. Nutrient burn

nute burn

Although cannabis plants need nutrients like every other plant, excessive feeding will do more harm than good. Also called “nute burn” or over-fertilization, nutrient burn occurs when you feed more nutrients than required. Since plants can’t deal with overfeeding, they absorb a lot more than needed and fall ill, much like how you’d react if you consume excess amounts of food. 

Typically, you’ll see three significant symptoms including:

  • Yellowing of leaves
  • Leaves turning a very dark green
  • Leaf edges look burnt or fried

Do not confuse them with yellowing leaves that occur naturally during the final stages of growth. In addition, the leaves may also turn brown and generally look miserable. Nutrient burn usually occurs due to excessive nitrogen that gets absorbed by the roots. It causes the leaves to discolor and burn themselves, resulting in the plant’s death or yield loss.

Although you can resolve nutrient burn if you catch it early, an advanced stage of nutrient burn may twist and curl the leaves. 

To fix nutrient burn, you can:

  1. First, snip off all affected parts of the plant to give it a chance to recover.
  2. Stop feeding any nutrients. 
  3. Drain all the reservoir water and refill with plain water. Allow the plants to recoup for at least 24 hours. Next, check the pH and EC levels. Repeat the process until you attain desired levels. 

2. Improper pH levels

Hydroponics pH Chart

Beginners are often intimidated by technical jargon such as PPM, NPK, pH, Lucas Formula, etc., and try to wing it. That’s the wrong way to grow healthy cannabis plants. The correct pH levels play a crucial role in the nutrient solution. 

Try growing cannabis organically — it’s the only way to avoid pH, PPM, EC, etc. 

For hydroponic growers, there’s no escaping any of it. To grow healthy cannabis plants, maintain pH between 5.5 to 6.5 — if the pH is under 5.5, it can cause nutrient lockout; if the same is over 6.5, it can cause a nutrient burn. 

Maintaining proper pH can seem complicated, so we have an entire guide right here if you want to master the basics of pH. Last but not least, investing in a high-quality digital pH meter is imperative if you wish for good yields. 

3. Cheap, unreliable equipment

hydroponics drip system

Hydroponics is an expensive hobby, but skimping on gear such as fans, lights, timers, etc., can significantly affect the results. Instead, we recommend buying the best equipment that offers reliability, fewer equipment features, and a good yield. 

Think of expensive equipment as an investment, not an expense — your yield will be directly proportional to your investment.      

4. Excess water in the hydroponics system

hydroponics airstone bubbles

The word ‘hydro’ in the name often confuses many newbie growers into thinking the crop requires a lot of water — that is a big mistake. 

The hydroponic root system largely depends on a good oxygen/moisture ratio within the medium, so overwatering can be disastrous. Overwatering can cause oxygen deprivation to any plant, and cannabis is no exception. 

Always ensure you have large airstones that generate lots of bubbles, so adequate oxygen and moisture are supplied to the medium without excess water. Also, ideal humidity levels should be between 45% to 65% for a healthy yield.

5. Thick organic nutrients

For a healthy hydroponic cannabis plant, the size of the nutrients needs to be much smaller than the organic compounds. If the nutrients are too thick, they can build up over time, block the drip lines, and lead to aerobic bacteria formation within the lines. 

In addition, many growers try to use fertilizers meant to grow plants in soil. However, since soil naturally contains many minerals and nutrients necessary for healthy growth, fertilizers meant for soil are inadequate for hydroponic systems. 

To avoid these problems, stick to fertilizers designed for hydroponics

6. Improper drip stake placement

Drip stakes function as an efficient way to water plants. They also saturate the grow medium with adequate water and nutrients. When combined with a timer, they encourage consistency. 

However, if the drip lines are not inserted correctly, it can prevent nutrients from reaching the medium, affecting the plant’s growth and health. 

The solution? Insert the drip line properly into your hydroton, rockwool, or coco medium, and ensure the nutrient solution is not squirting out. It needs to drip out of the lines closer to the rolls, and an ideal depth of the lines should be 3 to 4 inches into the medium, dripping downwards.

7. Sudden, significant changes to the method or materials

Sometimes, things don’t work out as planned, and you may want to fix the problem instantly by making drastic changes to your methods or materials. That is another mistake that you must avoid. Drastic changes often don’t give enough time to the plant to acclimatize to the process, causing lost yield and unhealthy growth.

Instead, if you face any issues, make incremental changes to see how the tweaks affect the growth on a small scale. This way, you will avoid any issues and get to the root of the problem without spending a lot of time and effort revamping the system.

In addition, don’t try to fix what’s not broken. Tweaking a setup unnecessarily will put your plants at risk.

8. Nutrient deficiency

nutrient deficiencies

It's tough to figure out whether your plants suffer from nutrient toxicity or nutrient deficiency as most symptoms are similar. For instance, nutrient toxicity can make the leaves turn yellow at times, and nutrient deficiency can also produce the same effect.

As explained above, a nutrient burn or toxicity occurs when you over-feed the plants. In contrast, nutrient deficiency occurs when the plants don't get adequate nutrients. In addition, numerous other factors can also cause both problems, so the best solution is to prevent such issues rather than correct them.

The good news is that you will identify the problems with ease as you gain more experience. Beginners should always keep an eye on the pH, nutrient solution, EC, and PPM to prevent issues in the first place. Excessive feeding of one nutrient can also cause a deficiency of another nutrient.

So, what's the solution to all this? Well, it's simple — just stick to one type of nutrient solution at all times. No matter how tempting it feels to switch to other nutrients because another grower uses them, always stick to what works for you. What works for another grower may not be suitable for you, and vice versa.

If you're unsure about the type of nutrient you can use, check out our vast collection of nutrients from different companies. Then, read the testimonials and create a plan — document everything you do as you go so you don't repeat the same mistakes.

If you see the plants suffering despite your best efforts, flush the water from the reservoir and start again. Again, monitor the pH levels and PPM, and stop feeding any nutrients until the plants start recovering. 

Next, prepare a new batch of nutrient solution and feed the plants after adjusting the pH. Although checking the pH seems overkill, you will have to do it until you gain enough experience. If nothing works, it's best to cull the plants and start afresh to avoid wasting time and effort.

9. Hard water

Those using organic soil to grow cannabis usually get away with hard water because it's forgiving. However, the same is not valid for hydroponics since the plants depend on the type of 

If you have no other choice other than to use hard water, dilute it with some distilled water. Next, check the PPM. If it's way below 200, you may not encounter major issues; however, if the PPM is significantly above 200, you will face problems as you continue to grow. Remember that tap water consists of large quantities of minerals such as magnesium, calcium, and dissolved solids that will interfere with the nutrient solution.

Both calcium and magnesium can cause various problems when used in excess amounts. If the problem persists, the plants may stop absorbing other nutrients completely, leading to more problems. In addition, with no way to find out the exact levels of calcium in the tap water (unless you get it tested before adding the nutrients), it will become challenging to prepare a well-balanced nutrient solution.

To avoid these issues, it's best not to use hard water in the first place. But, hard water is usually the easiest and least expensive source, so you can do a few things to tweak it to suit your purpose. 

Firstly, most municipalities use chlorine and chloramine in tap water. If your water contains chlorine, simply place buckets of water in sunlight for at least 48 hours to remove chlorine. If it contains chloramine, use an activated carbon filter to purify the water. You can also use Campden tablets to eliminate chloramine and chlorine.

If your tap water displays significantly high PPM levels, then invest in a reverse osmosis filter. However, they can be expensive, so the best alternative is to use lots of distilled and purified water to balance the PPM levels. 

Here are a few grow journals that show you how to grow cannabis hydroponically:


Growing your cannabis using a hydroponic system can be rewarding, provided you follow some fundamental rules. 

Here’s a step-by-step guide if you want to start growing cannabis in hydroponic systems right away. 

With hydroponics, remember that practice goes a long way. If you’re new to it, keep growing until you get better because there’s no shortcut. The good news, however, is that once you get the hang of it, you’ll have loads of buds in no time.


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