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How to Grow Cannabis Hydroponically

Last updated: April 24, 2020


Using hydroponics to grow cannabis is not as complicated as it seems, but all the new terminology and techniques can be a bit overwhelming for beginners. For those who take the time to learn the system, the benefits are profound.

Hydroponics offers a way to grow cannabis without the fear of soil-borne illness, which is a common killer for the beginner grower’s plants, and increases the yields by as much as 25% when done correctly. There are quite a few things to understand before jumping directly into a hydroponics grow, so let’s go over the basics:

Finding a Good System

There are a few different ways to go about a hydroponic system. DIY systems are just as popular as ones on the market, but they all go about things in a similar manner.

The gist of it is that the roots of the plant grow into an inert soil, such as perlite, and come into contact with a nutrient solution via a couple of different methods.

Hydroponical cannabis

Photo by BiW99 on Pixabay

Reservoir or Deep Water Culture

This method involves allowing the roots of the plant to dangle directly into a nutrient bath reservoir. An aquarium bubbler is placed into the reservoir to constantly aerate the water. Algaes are sometimes allowed to grow in this reservoir to add additional nutrients and enable filtration of the tank.

Ebb and Flow

Ebb and Flow is probably the most popular beginner method and widely available for sale from a lot of different manufacturers. The way it works is pretty straightforward. A nutrient solution is pumped onto the growing medium the roots are entangled on—Rockwool is very common for this— and slowly drains into the reservoir.

This is kept on a timer and can be adjusted to suit the needs of the plant.


Unlike the previous two methods, both which are variations of a liquid nutrient bath, this one uses a spray to get nutrients to the roots. Triggered by a timer, the nutrient aerosol is sprayed a few times a day onto the dangling roots of the plant. The roots grow quite long because of this and it allows for a lot of oxygen to penetrate them easily.


In fertile soil, a lot of the essential minerals for growth are already there for cannabis to use; however, with hydroponics systems, you need to add these yourself. Solutions come pre-prepared to resolve a lot of the guesswork, but knowing what these specific elements are can help understanding in the long run.

The main ingredients needed for a healthy plant are nitrogen, phosphorous, and potassium. These come in different blends at different percentages, depending on the stage of growth the nutrients are recommended for.


Featured Image Credit: Pxfuel


As the plants absorb the water, the tanks reservoir will slowly lower and need to be refilled. The water should be brought back up to level, without adding any more fertilizer or nutrients to the mix. The water is evaporating, but all those compounds are not and will remain in the water at an appropriate level.

Once every two weeks, the whole system should be cleaned out to avoid gunking and other nasties that may have built up, which is when you should add more nutrients to the mix.

How to Begin

Set up your reservoir basin without nutrients and ensure that everything is in working order before adding plants and nutrients to the mix. This helps figure out any problems down the line by cutting variables during tests.

Now, add the nutrients to the solution, and if needed make sure air will be getting into the water via an aquarium bubbler. Run that, make sure everything in working order, and check the balance of the water.

Hemp Plant

Featured Image Credit: MasterTux, Pixabay

pH Levels

pH is the measure of acidity in a medium. Certain plants like different levels of acidity to survive with cannabis enjoying a pH between 5.5 and 6.5. Before adding plants to the nutrient bath ensure that the pH level is between these numbers.

After all of this is done then the plants can finally be added to the set up without issue.


Lighting systems for hydroponics are pretty similar to any other grow. The only thing to consider is the amount of humidity within the room will probably increase due to water evaporation.

LEDs or well-cooled HPS systems are ideal for this, as it can get downright steamy in an enclosed hydroponic set up if the temperature is off. Other than that, the general rules of 18 hours on and 6 hours off apply throughout both seedling and vegetative stages, with the 12 hours on and 12 hours off kicking in once it’s time to flower.


In general, a hydroponic grow won’t differ from a standard grow in most ways, aside from considerations needed to keep the tanks full and the room from getting too wet.

Make sure to check the water pH levels at least a few times a week, as you add more water to the system this will change over time. Nutrients as well can have a significant impact on the balance of the water and should be counteracted to ensure healthy plants.

Hydroponics are a joy and can create massive yields. Hopefully, this helped pick apart some of the details of the process.

Featured Image Credit: BiW99, Pixabay