Marijuana grown hydroponically uses a growing medium other than soil. Rather than using soil’s natural nutrients, they will add nutrients to a soil substitute. Examples of alternatives to soil include Coconut Coir, Rockwool, and Perlite. Hydroponics users prefer the method because it is less likely to attract pests.
It is a good option for growers with experience because they get the opportunity to control nutrient intake. You can use your knowledge to generate a harvest with a higher yield. Proponents of hydroponics also suggest that the cannabis they grow has a superior taste to what’s grown in soil.
However, there are numerous issues to contend with. As you are in control, your crop requires constant attention. A hydroponic system exposes the roots to severe damage if you run out of water or suffer a pump failure. Even a slight change in pH can cause immense issues! While hydroponic marijuana is less susceptible to disease, illnesses run rampant once they ‘get in.’
If you are new to growing cannabis using a hydroponic system, you will likely make a mistake or two. Failure to rectify the situation can have devastating consequences. Fortunately, there are several errors that novices make over and over again. Even better, it is possible to ‘fix’ things before they get out of hand. In this guide, we outline five common hydroponics problems and how to solve them.
Eager to learn more about this method of cultivating cannabis? Check out our detailed guide on growing hydroponic marijuana.
1 – Choosing a Nonoptimal Hydroponic System for Your Grow Space
It is possible to create a hydroponic system in a relatively small grow space. The available options include:
- Drip System
- Nutrient Film Technique (NFT)
- Ebb & Flow System
- Deep Water Culture (DWC)
- Wick System
Of the five options outlined above, NFT is for advanced growers. The drip system is for intermediates, and the others are suitable for beginners. Before choosing a hydroponic system, consider your experience, skill level, finances, and space. If you don’t think about efficiency and workflow, you end up with a farm that:
- Is difficult to harvest
- Doesn’t use space efficiently
- Isn’t good at pest control
- Involves a lot of transplanting and maintenance
- Doesn’t enable you to access crucial components
Growers who have a system in their basement often make an elementary mistake. They place their nutrient reservoir at the side of the grow table. When they need to ‘flush,’ they find that a bucket is the only way to drain their tank.
The Fix – Map out a Plan
Those with a low budget and minimal space should lean towards the Wick System. It is arguably the easiest to implement. The more parts in your cannabis garden, the higher the risk of problems. Your grow tray gets its nutrients from a wick made of yarn or cotton, which brings the nutrients to the roots.
When using the Wick System, use smaller plants because larger ones require a lot of water. They could also potentially use the nutrient solution faster than you can supply it. Bear in mind that the Wick System is also the least efficient, and may produce the smallest yield. However, you are less likely to encounter problems.
As a general rule, make sure you consider all variables. This includes growing needs like light and water, and user needs such as convenience and access. If you are a beginner, there is no need to shoot for the stars. Keep things simple at first, understand the hydroponics process, and learn. Meanwhile, enjoy the yield from your first successful operation!
2 – Lack of Attention to pH Levels
This is an issue when initially transitioning from soil to a different growing medium. You are so used to soil remaining in its pH zone that you forget its importance. In soil, the ‘ideal’ pH for cultivating cannabis is between 6.0 and 7.0. In a hydroponics system, it is between 5.5 and 6.5. It’s easy to underestimate the difference a few pH points make. The pH scale is logarithmic to the base 10. Therefore, water at a pH of 5.5 is ten times more acidic than at 6.5.
The pH of a growing medium has a profound effect on its nutrient uptake. If you grow weed outside the right range, your plants will experience ‘nutrient lockout.’ From there, it doesn’t take long for cannabis nutrient deficiencies to manifest. However, it isn’t merely a case of allowing the pH to remain at a certain point. It is necessary to enable fluctuations within the specific range.
Nutrients such as calcium and magnesium are absorbed at a pH of above 6.0 in general. However, the likes of manganese and phosphorus prefer a slightly lower pH. In a hydroponics system, you are solely responsible for adding nutrients directly to the root zone via water. As a result, significant fluctuations in pH are more likely than in soil. It doesn’t take long for it to become a problem.
The Fix – Monitor, Test & Adjust
The process of testing your nutrient solution or water for pH levels isn’t nearly as complicated as it seems. You can easily purchase a pH measurement kit with drops or a digital pH meter online. Make sure you test the pH after every occasion where you add nutrients as they change your water’s pH level. Wait a few minutes and test a sample from the water reservoir.
If the pH level is out of the optimal range, there are special ‘pH +’ and ‘pH – ‘products on the market. If you are using tap water in your reservoir, it is likely the pH will be above 6.5 as the water is close to 7.0. It usually only takes 1-2ml of the solution per gallon of water to make a positive difference. Stir the product into the water and wait for up to 30 minutes to test the pH again. Repeat the process if the pH remains outside the 5.5 to 6.5 range.
Citric acid and white vinegar can lower the pH. Baking soda is commonly used to increase pH. You can use these items in a pinch, but they are only short-term fixes at best.
3 – Incorrect or Excessive Nutrients
Don’t make the mistake of thinking the only thing you need is a good water to solution ratio. Your crop requires different N-P-K ratios and other minerals at varying stages. For example, plants in the vegetative stage require a high degree of nitrogen. The focus shifts to potassium and phosphorus in the blooming stage.
Some growers buy a sack of fertilizer from their local store and use it in their hydroponic system. ‘Regular’ fertilizer could clog tubes and drains, and may not dilute thoroughly. Also, you can cause as many issues overfeeding as you do from underfeeding. It is far too easy to produce a nutrient burn, a process that hinders yield.
The Fix – Know Thy Nutrients
It isn’t all about N-P-K. You must learn to add sufficient levels of micronutrients such as magnesium, calcium, sulfur, and manganese, for example. However, Nitrogen, Phosphorus, and Potassium are three of the six macronutrients a plant needs to live. The other three, oxygen, hydrogen, and carbon, are supplied by air and water.
Rather than buying traditional fertilizer, invest in specific hydroponics nutrient packages. On the front, you should see the N-P-K content. If the product says 7-5-5, for instance, it means 7 parts nitrogen to 5 parts potassium to 5 parts phosphorus. Though there are no specific ratios, experienced growers suggest the following:
|Plant Growing Stage||Suitable N-P-K Ratio|
|Early Vegetative Stage||4-2-3|
|Advanced Vegetative Stage||10-5-7|
|The transition from Vegetative to Flowering Stage||7-7-7|
|Early Flowering Stage||5-10-7|
|Full Flowering Stage||6-15-10|
|Final Flowering Stage||4-10-7|
4 – Lighting Issues
If you skimp on lighting, you will never enjoy the results you crave. Too many growers believe it is a case of buying the strongest light as possible, and to hell with the consequences!
In reality, marijuana plants require lighting at different spectrums according to its growth stage. They also need a specific intensity, and you must get the duration correct also. Most growers know what happens when their plants don’t get enough light. However, if the intensity is too high, you end up with short and stout plants.
In the beginning, most hydroponics growers used High-Intensity Discharge (HID) lights for growing. While HID lamps provide plenty of light, they also waste a ton of energy. Therefore, you need to invest in a high-quality ventilation system. HID lamps also require a ballast.
LED lighting has come to prominence in recent years. They provide a spectrum ideal for every growing stage and don’t require a ballast. Other lighting options include high-pressure sodium lights and Metal Halide (MH) lights. You can learn more in our best grow lights for indoor weed guide.
The Fix – Understand the Light Spectrum
All plants, including cannabis, use energy from light during the process of photosynthesis. The pigments in plants absorb specific wavelengths of light and reflect the rest. Though there are several essential pigments in the photosynthesis process, chlorophyll and carotenoid are the most critical.
You can customize LEDs to provide the precise colors your plants need at different stages. Make sure you purchase full-spectrum LED grow lights. By doing so, you ensure there’s no need to change the light when your plant changes growing stages. Ideally, your lights contain:
- White LEDs
- Far-Red LEDs
- Blue LEDs
- Red LEDs
It is also okay to include some green, IR, and UV LEDs. When you buy the right LED lighting, you’ll find they are configured for all growth stages. As a result, the colors are mixed, and you get the purple hue often associated with LEDs.
Bulbs are measured by color temperature in Kelvins. Above, you can see the different Kelvin measurements for varying forms of light. It is a little complex, but let’s simplify it by outlining ‘ballpark’ ranges for the various stages of growth:
- Seedlings & Clones: Bulbs at 5,000 Kelvins are useful. Fluorescent lights are a good option here.
- Vegetative Growth: Bulbs in the 5,000-7,000K range work well, and you can use Metal Halide lights.
- Flowering: Drop the range to 2,000-3,000K here. High-pressure sodium bulbs are a good option as they produce more red light.
Remember, LED lighting is an excellent option for every stage.
5 – Lack of Sanitation
Hydroponic systems are a sterile environment. This means the entire grow room and not just the plants you are growing. The benefit is that your plants remain free from pests and diseases. However, if any harmful bacteria or parasites get into the system, they can spread rapidly and ruin your harvest.
The nutrient reservoir could have algae buildup, and the nutrient mix may cause an increase in salt content. In this case, the salt sticks to the pots and growing medium. Also, the warm and humid air in the room increases the risk of mold growth.
The Fix – More Attentive Gardening!
This is perhaps the most straightforward fix because it doesn’t require much technical skill. Instead, it involves diligence and a willingness to put in the time and effort needed. Your first goal is to ensure the floors are clean, dry, and sterilized at all times. Make sure you clean every single tool used in the system before use.
Whenever you flush your system, check nutrient reservoirs. It is the same situation with grow beds and piping. Make sure you rigorously check your pots and growing medium and clean them if you see a salt buildup. Also, remove plant waste as soon as you spot it. Any diseases caught by one plant will rapidly spread to the others.
We recommend investing in a high-quality fan to circulate air in the hydroponics room. This process also helps bring in fresh carbon dioxide and oxygen and keeps the temperature at a manageable level.
Did you know that the amount of dissolved oxygen in your nutrient solution diminishes as the temperature increases? A lower level of oxygen damages root health. Excessively high temperatures also invite the presence of pathogens. Ideally, you will keep the nutrient solution at between 65- and 75-degrees Fahrenheit.
Final Thoughts on Hydroponics Problems & Their Fixes
It is all too easy to suggest growers can avoid these mistakes through the use of common sense. Even experienced cultivators of cannabis make the occasional blunder, and they tend to learn from it. The trouble with hydroponic growing is that minor errors can have a significant impact on the health of your harvest. It is a process that involves a lot of effort and focus. You can ‘get away with’ making mistakes. What you can’t afford to do is overlook them. It doesn’t take long for a ‘simple’ misstep to turn into a catastrophe.
Ultimately, a successful hydroponics grow is all about preparation, concentration, and monitoring. Outline the best ‘type’ of system and closely monitor your plants’ pH levels. Learn more about nutrients and how much you need to add at every stage. Ideally, you will save yourself a lot of trouble by purchasing LED lights. Otherwise, you will need to make constant adjustments. Finally, keep your grow room sterile or face the consequences. You can do all of the above through regular checking of your crop.
If you are not using a hydroponics system, you certainly don’t escape if you make a mistake! Though you have less involvement, there several things to remember when using soil. Check out our guide on 10 things to never forget when growing cannabis. It could save you a lot of time and frustration.