How to Grow Weed Using Nutrient Film Technique (NFT)

In this article we explain how to grow weed using the Nutrient Film Technique (NFT) , how it works, what to avoid and top tips. One of the greatest things about growing Cannabis using hydroponics is how versatile the different systems can be. An excellent example of this is an NFT system which is used commercially for large-scale farming across the world. Nutrient Film Technique is a very simple system that uses gravity, a pump, and rockwool cubes.

How does nutrient film technique work?

An NFT (Nutrient Film Technique) system comprises a reservoir below and tray above that the plants in rockwool cubes permanently sit in, allowing them to bottom feed for the duration of their lifecycle. As the top tray is angled downwards slightly, gravity allows the nutrient solution to flow evenly down a white rooting mat and to return back to the reservoir where a small-sized pump will release the nutrient solution back down the upper part of the tray.

Nutrient film technique works by allowing a continuous streaming motion without the concern of drowning the roots. A cover is used to place over the rockwool cubes to block out light and prevent algae forming. Once the pump has been turned on, the system can be left to run 24 hours a day and should not be turned off like other hydroponic systems such as dripper or flood and drain.

Commercial-scale farmers in the USA choose to grow lettuce and other smaller-sized plants in NFT hydroponics using white plastic tubing, where the nutrient solution flows down and returns via a pump. This allows them to take advantage of the space and, by planting the lettuce inside rockwool and then allowing them to sit in net pots, the roots can begin to work their way into the pipe canal. When growing Cannabis using hydroponics , this type of design is also perfect for making vertical systems that can house smaller-sized plants.

How often does the NFT hydroponics reservoir need changing?

When using the nutrient film technique hydroponics method, generally a cannabis grower will want to change the reservoir and to refill it with fresh nutrient solution once a week. The way to do this correctly is to attach a hose to the pump and then siphon the water out into a toilet or nearby drain if there is no other option, but to minimize the environmental impact the better option is to release the solution into a garden space. Growers need to make sure that the new nutrient solution filling the reservoir has been adjusted to the correct pH and E.C.

The advantages of using hydroponics system NFT to grow cannabis 

Having discussed how nutrient film technique works, let’s review the benefits of using a system which has been around for decades and used by farmers to maximize outdoor / greenhouse hydroponics. The benefits associated with the hydroponics system NFT  method are:

• The level of maintenance is oftentimes minimal.
• An excellent entry level system for a beginner grower.
• The system can be very quiet when the pump is switched on.
• Plants can grow very quick during the vegetative stage.
• There is no growing medium to throw out.
• It is very easy to make your own homemade NFT system.
• Ideal for vertical systems that use white pipe and spiral downwards.
• Utilizes space incredibly well.

The correct pH and E.C levels for growing cannabis with NFT hydroponics.

If growing Cannabis using hydroponics (including the nutrient film technique hydroponics principle) , it is essential to maintain the correct pH and E.C levels for the roots to uptake nutrients at an optimal rate. The ideal pH for NFT hydroponics systems is 5.5-6.0 and your E.C levels of 1.5-2.5 depending on the strains and stage of the Cannabis plant’s life cycle.

3 Things To Avoid Using NFT Systems

As simple as these systems are, it also means that things may go wrong quickly if you do not follow certain protocols. Below are 3 things to consider that can cause a nutrient film technique hydroponics system to cause problems and what to avoid when growing Cannabis using hydroponics.

1. Do not use organic nutrients when using any hydroponics system, especially nutrient film technique. Hydroponic nutrients are created in a much smaller mineral size in comparison to organic liquid nutrients so will only cause the pump to block and allow the nutrient solution to become stagnant and dominant in anaerobic bacteria.

Top Tip: Buy nutrients made especially for hydroponics. These will be a bottled range of nutrients that will be 2-3 parts.

1. Make sure that the top cover of the nutrient film technique hydroponics tank is fully fixed and there are no light breaks through as algae can form very fast and spread onto the root mat. This can be treated using hydrogen peroxide, however it is easily avoided in the first place by regularly checking the top lid is on correctly.

Top Tip: Using a black, light-proof top cover is best advised. This will keep the light out and the roots in darkness and guarantee no development of algae. 

1. The temperature of your nutrient solution should never be allowed to become cold to the touch. When growing Cannabis using hydroponic systems, you should aim to keep a consistent temperature of 18-21 degrees Celsius in order to prevent nutrient lock out and shock the plants also.

Top Tip: Placing an aquarium heater at the bottom of the reservoir tank is the best way to keep your temperatures in the right zone. Adding a heater will make a huge difference when growing Cannabis using hydroponics