10 Key Tips for Growing Cannabis Using Hydroponics

By Chris Bond
Published: February 14, 2018 | Last updated: May 11, 2022 03:36:52
Presented by Crop King Seeds
Key Takeaways

Getting started using hydroponics to grow cannabis can be tricky. Here are ten tips to make it a little bit easier.

The cliché “an ounce of prevention equals a pound of cure” may well be overused, but it is still a good measure to use when growing cannabis. If enough attention to detail is taken during the setup phase of a hydroponic grow operation, then the chances for a successful crop are greatly increased.

The precise course of action taken will depend on your unique space and resources, and of course any unique needs of the particular strain of cannabis that you are growing. All that aside, there are still some tasks and practices that should be observed in any hydroponic growing area to keep your plants as healthy and productive as possible.


1. Start With Sterile Tanks and Equipment

If you can afford to buy all new equipment to start your growing operations, this step may not be necessary at first, but eventually all tanks, reservoirs, pipes, filters and any other physical part of your hydro system will need to be sanitized to prevent the development and spread of pathogens, especially root rots. Plan on having several bottles of isopropyl alcohol and hydrogen peroxide on hand to disinfect your equipment on a regular basis.

2. Make Sure You Start With Clean, pH Neutral Water

Ideally the water circulating through your hydroponic system is at a pH of 7. If not, a reverse osmosis (RO) system will create and provide neutral water. Distilled water can be used as well until an RO system can be obtained.


Read also: 7 Ways to Disinfect Hydroponic Nutrient Solution

3. Watch Your Temperatures

Ideally the water flowing through your system will be about 65 F (18 C) to facilitate good nutrient absorption and to prevent the buildup of algae. The air temperature, however can be warmer. If you can achieve about 75 F (24 C) in your grow room, your marijuana plants should be quite content.

4. Maintain Proper Humidity Levels

Cannabis plants do best in varying levels of humidity based on their stage of development. When your “girls” are young, they need to have humidity levels in the 60-70 percent range. As they develop and move into the blooming phase, they only need about 40 percent humidity. This can be best achieved with a humidifier and dehumidifier used accordingly.


5. Attain Proper Lighting

There are numerous types of grow lights out there and champions and critics of all. The right types of grow light for your setup will depend on your space, the distance between your lights and your plants and your budget. High Intensity Discharge (HID) lights are better for larger grow rooms with good airflow and ventilation. Compact Fluorescent lights (CFL) are better for smaller rooms. Light from Light Emitting Diode (LED) fixtures is good for small grow areas, but is more costly than the CFLs. Whichever type is selected, make sure that it can produce light in sufficient amounts between 400 and 700 nanometers. A relatively inexpensive light meter can help to determine if your grow lights are getting the job done.

6. Maintain Proper Ventilation/Air Flow

Keeping the air moving around is critical for plant health and aids in even temperature distribution. Fans should be mounted or placed so that they can cover the most area unobstructed. Proper ventilation will help to maintain appropriate air temperatures if it gets too hot, but will also help with air exchange.


7. Understand pH

Fortunately this is not difficult and there are meters that can take pH readings. This is important because if the pH of your water is not in the proper range, your plants will not grow well or may even die. For hydroponic cannabis, aim for a pH of about 6.0, but allow for a range between high 5s and low 6s.

Read also: What are the Best pH Levels for Growing Cannabis?

8. Understand EC Readings

Electrical conductivity (EC) is a measure of the total dissolved solids (TDS) in your hydroponic water. Like with pH, there are many effective meters on the market and there are many that take both readings (pH and EC). The EC level will tell you how rich in nutrients your circulating water is. If the EC is too low, your plants aren’t getting enough; if it’s too high, you can “burn” your plants with too high of a nutrient level. The EC for hydroponically grown cannabis will fluctuate depending on the stage of growth.

As seedlings or clones are first put into a system, the EC levels should be less than 1.3 and can be as low as .5 for clones. When they start to grow however, expect to maintain an EC level that continually climbs toward 2.0. When your plants finally reach the flowering phase, they may need an EC up to almost 2.5 depending on the strain grown. Check your EC levels often. The closer you can maintain proper EC, the more productive your cannabis plants will be.

9. Find A Reliable Seed Source

All of the planning, preparation and procuring of necessary products can’t make cannabis of poor genetics into a robust strain. A cannabis plant can only produce what it is genetically predisposed to produce. Improving its growing environment and attending to its needs ensures that it will come as close to this potential as possible.

10. Keep Good Records

You cannot improve what you cannot measure. Even the best growers have bad crops and sometimes novices get lucky. To remove as much of the “luck” factor and to focus on results, keep track of everything. The more detailed notes you keep on temperatures, planting dates, EC levels, pH levels, humidity levels and any other factor that you can measure, will allow you to make informed decisions going forward to make continual improvements or to maintain high yields.

Read next: What’s Better: Growing Cannabis in Soil or Hydroponics?


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Written by Chris Bond | Certified Permaculture Designer, Nursery Technician, Nursery Professional

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Chris Bond’s research interests are with sustainable agriculture, biological pest control, and alternative growing methods. He is a certified permaculture designer and certified nursery technician in Ohio and a certified nursery professional in New York, where he got his start in growing.

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