How to Grow Cannabis Using the NFT (Nutrient Film Technique)?

Are you looking for a different way to grow cannabis? 

Try NFT, aka Nutrient Film Technique.

As another variation of hydroponics, it’s not too tricky to master. 

NFT has become quite popular in recent times to grow cannabis as it helps you grow plants quickly with bigger buds.

In a structural sense, the NFT method is a continuous flow hydroponic system, pretty similar to the ebb and flow method. 

However, is it worth trying the NFT?

Or is it just another technique that doesn’t bring anything unique to the table?

Let’s find out.

About Nutrient Film Technique

The nutrient film technique (NFT) is a hydroponic variation that submerges a part of the roots in a thin nutrient + water film — hence the name — and permanently exposes the rest of the roots to air. 

This is done because although the nutrient solution is crucial for the plant, the roots also need air. Without oxygen, the plants just won’t grow. This way, the system makes it easier for the roots to absorb nutrients from the water and air. 

In an NFT system, cannabis plants are grown in long channels, called troughs, using net pots to hold them in place. And the nutrient film is continually circulated along the bottom of the troughs using a water pump. 

Benefits of NFT Cannabis

While NFT cannabis systems ensure faster growth, they offer many advantages over other growing methods. Let’s look at the best benefits of NFT systems for growing cannabis.

Most hydroponic techniques rely on using growing media, but since NFT offers you the opportunity to grow plants without a medium, it makes it very easy to control many things in the system. For example, it is very easy to check for root diseases and correct them immediately with NFT. It is also relatively easy to clean the system compared to other hydroponic techniques.

• Faster growth and bigger yields

The NFT method lets you achieve up to three times the yield of traditional growing methods, which is a terrific advantage. Plus, the plants tend to grow rapidly due to the controlled and continuous flow of nutrients.

• Cheaper to set up

Compared to other hydroponic systems that require misters and timers and whatnot, an NFT system is easier on your wallet as well. You can further reduce the costs by constructing a DIY NFT system (we will get to this later) if you don't want to spend more on commercial ones. However, if you plan to grow too many plants, it's best to go for commercial setups since they reduce your chances of committing mistakes.

• Better tasting buds

The method gives you optimum control over the growth process, letting you finely tune everything, including the pH, nutrients, and water, according to your plant’s needs. Naturally, the plants will also respond in kind and produce fantastic buds. 

• Simplicity 

Most hydroponic systems are terrific techniques to grow better cannabis, but a lot of them are complex and challenging to maintain (*ahem* aeroponics *ahem*). On the other hand, NFT systems are pretty easy to take care of. Note that it’s a bit challenging to set it up, but it’s smooth sailing after that. 

• Eco-friendly

Cannabis is a thirsty plant — it drinks one gallon of water for every usable pound of cannabis yield. However, an NFT system uses minimal water, reducing water loss, as it constantly recirculates and self-contains water.

• Accurate feeding

In an NFT method to grow cannabis, plants only consume nutrients that are required — neither less nor more — thanks to the controlled and steady nutrient supply. This ensures the plant stays healthy and avoids overfeeding and nutrient burn issues. It also takes the guesswork out of the equation, so you have to do nothing other than maintain the nutrient solution. 

In addition, the plants will also maintain a stable pH at all times, which is one of the most important factors in growing cannabis. What more, you reduce the chances of contaminating groundwater, making it an eco-friendly option. 

• Fewer pests

Since the system doesn’t use organic media like soil, the chances of harmful microbes damaging your plants are less. Also, with no media, pests that hide and thrive in the soil will avoid the plants, reducing the chances of pest infestation drastically.

NFT Cannabis System Drawbacks

Similarly, you will experience a few problems with the NFT system. Here are a few things you need to watch out for:

• Stress

Although the lack of growing media is an advantage in the NFT system, it can cause problems if you don't pay attention. For instance, other hydroponic systems utilize Rockwool as the growing medium that holds adequate water to keep the roots moist even if the supply stops for a short period. However, with no growing media in the NFT system, the roots will be stressed immediately if the nutrient solution flow stops.

In addition, setting up an NFT system outdoors might not be a viable solution especially if there's intense sunlight because the channels could get hot very quickly and cook the roots (literally!). So, although the nutrient solution helps keep the roots somewhat cool, it's best to set up the NFT system indoors.

• Regular maintenance

NFT systems require regular root health monitoring. From checking the pH of the water to diagnosing root issues, you'll also have to trim the roots frequently, so they don't block the channels. This can be pretty intimidating for beginners since messing with the roots is not an easy task.

• Additional costs

It’s very difficult to grow plants using NFT if you don’t have a reliable power source to run the pumps. Even an overnight power outage can kill your plants. 

Additionally, you need to properly tune in the air, water, and nutrient supply to ensure a healthy plant. A small mistake can lead to problems like nutrient burn, stunted growth, algae, etc.

Therefore, we only recommend intermediate and advanced hydroponic growers to use the NFT technique to grow cannabis.

Four Factors to Consider When Growing NFT Cannabis

To avoid the aforementioned problems, you need to consider four factors: gradient, flow rate, temperature, and channel length to grow healthy cannabis plants. Let’s take a look at them in detail.

• Gradient or Slopelope

The gradient is the angle at which the NFT channels are placed — it is crucial to the nutrient solution flow. The slope in the troughs allows the nutrient solution to flow smoothly, keeping it from pooling around the roots. This is to prevent root rot or nutrient imbalance due to the pooling.

You can create the gradient in various ways — you can place the channels on a frame, benches, or a sloping floor, but it can be a bit tricky! Theoretically, you need a gradient of 1:100 (1%), but we recommend using a slope of 1:30 (3.33%) or 1:40 (2.5%). 

• Nutrient Flow Rate

Next, you need to focus on the nutrient flow rate — it dictates how much nutrient is available to the roots and its depth at the troughs’ bottoms. Both are crucial for the healthy growth of the cannabis plant. 

The flow rate is a result of the gradient and pump. Therefore, you need to choose the gradient as recommended above and a flow rate of one liter per minute. You can lower the flow rate to 500 ml per minute when introducing new plants.

• Channel Length

Lastly, you need a channel length that ensures proper nutrient distribution to each plant on the channel. If the length is too long, the plants sitting at the far end may suffer.

Plus, the length is crucial to boost oxygen levels in the solution. Pro-tip: use air stones to increase oxygen levels in the nutrient solution. 

The actual length of NFT’s channels depends on factors like gradient, culture size, nutrient concentration, etc., but we recommend you never exceed 30-40 feet for your channel size. 

If you are growing commercial cannabis, you may require longer channels. In this case, we recommend placing multiple nutrient feeds along the channel to optimize nutrient distribution.

• Temperature Control

Maintaining the right temperature is crucial for healthy growth, but it can be challenging in an NFT system. 

Long channels can lead to significant temperature fluctuations in the nutrient solution. Additionally, the exposed roots lack the natural insulation of soil or growing mediums, causing temperature fluctuations on the roots.

Why is this an issue?

As the temperature rises in the nutrient solution and environment, the Biological Oxygen Demand (BOD) of your cannabis plant increases, i.e., your plant needs more oxygen. Plus, the higher temperatures reduce the nutrient solution’s ability to retain oxygen.

Therefore, it’s best to maintain a temperature of around 65° F to 75° F.

This recommended range is warm enough to promote vigorous cannabis growth while being cool enough for the solution’s nutrient retention.

You can use heating or cooling systems in your reservoir to maintain the right temperature. We also recommend using reservoir insulation and polystyrene pads under the channel to optimize temperature control on your cannabis NFT system.

Setting Up an NFT System

Like other hydroponic systems, you have the option to choose between a pre-built NFT system or DIY-ing one to grow cannabis. Below, we discuss both options in detail.

Pre-built NFT System for Cannabis

Just search on Google, and you will find hundreds of NFT systems that you can use to grow cannabis. If you don’t want the hassle of setting one up and don’t mind investing some money, this is an ideal route to grow healthy cannabis.

However, it pays well to research individual models. Read the reviews and discuss the models with experienced growers to find the best one for you.

You also need to consider the space available. The system must fit in your room while leaving a lot of space for the plant to grow, not to mention some space for you to manage the plants. 

Lastly, choose an NFT system that is suitable for your lights. For example, if you have a 1000 watt HPS lighting system, choosing a small NFT system doesn’t make sense, does it?

DIY NFT System to Grow Cannabis

On the other hand, if you don’t want to spend a lot of money and just want to experiment, we recommend building your own. Then, all you need are elementary DIY skills (and in-depth knowledge of hydroponic concepts) to set up your NFT system.

To set up a DIY NFT system, you’ll need two primary components: the reservoir and the grow tray. 

Equipment Required:

1. Reservoir tank (at least 20 liters)
2. Grow tray with troughs (you can use PVC pipes)
3. Framework or benches to support the grow tray
4. Submersible water pump with a flow rate of 1 liter per minute
5. A water cooler or heater
6. Airstones (optional)

As you may have understood by now, the NFT technique uses grow trays or channels positioned slightly downwards to enable a stable nutrient flow. Other growing techniques use flat trays, but you will need to plan the structure for NFT.

You can also use channels, including PVC pipes, tubes, and plastic films, to create the grow tray. You can use anything that allows you to make holes easily, so the plants can get all the nutrients they need. They should be shallow enough to hold the roots. You can also place the trays on the reservoir to act as a cover.

Thankfully, all materials required for NFT are inexpensive and readily available both online and in your local hydroponic store, so you won’t have to search hard for them. 

Coming to the PVC pipes, using them can present a few issues. For example, the film will fail to coat the plant roots evenly. In addition, since the pipes will be positioned slightly at an angle, the plants sitting in the center will have more access to the nutrient solution, whereas the plants on both ends will not get as much nutrients as they need. This may result in healthy plants in the center with unhealthy plants on both ends. To prevent this problem, simply go for flat bottom channels.

Next, regarding the positioning of the seedlings, you have two choices. You can place the seedlings directly in the PVC pipe or channel holes or use net pots to hold them. Net Pots are better as they protect the roots.

Coming to the growing medium, you can fill up the net pots with Rockwool or hydroton, but do not fill it up too much as it may be difficult for the roots to get down to the bottom. In addition, you should remember to trim the roots frequently so they don't get tangled and clog your system.

Also, as mentioned earlier, consider the length of your grow trays before setting up the system. For instance, using shorter trays will serve you better in the long run because even plants sitting at the very end of the channels receive optimum nutrition just like the ones sitting in the beginning. However, if you only have long trays, you'll need to replenish the nutrient solution constantly and check the pH often to ensure everything is fine and dandy.

Finally, It is important to consider the reservoir capacity before setting up the system. You need a reservoir with at least five to six-gallon capacity for growing 5 plants. The reservoir must be big enough to hold an air stone and an air pump used to increase the oxygen. 

Also, keep in mind that you need an additional power backup source if there is a power outage or something goes wrong with the system. This is because the NFT technique lacks a timer, unlike other popular hydroponic systems, which means that the water pump will have to run constantly. A power outage for a short period can shut down the system entirely, so be prepared well in advance when you set up the NFT system.

Steps to Set Up an NFT System:

Take a PVC pipe and cut it according to your preferred size. 

Next, drill some holes in the pipe, depending on the number of plants you want to grow. These holes must be large enough for your net pots to fit in. Therefore, measure the pots before drilling holes. 

Additionally, drill holes in the PVC pipe end caps. 

Next, drill two holes at the top and bottom of the pipe.

Now, attach the end caps.

Next, set up an easy-to-access reservoir of at least 20 liters and ensure it is entirely light-tight to prevent algae buildup in the nutrient solution. Drill two holes in the reservoir as well. 

Now, you’ll need a stand to hold the channel upright, and you can use wood, PVC, or metal to make the stand. However, remember that the PVC pipe that rests above should be in a slightly slanted position. Therefore, create the stand in such a way that one end is slightly smaller than the other. 

Use rubber pipes to connect the reservoir to the higher end of the grow tray and another pipe to connect the lower end of the tray to the reservoir.

Now, add the submersible pump within the reservoir and connect it to the pipe leading to the tray to push the nutrient solution up. If you want to use airstones, then install an airstone within the reservoir.

Fill the reservoir with water and nutrient solution and run the pump. 

Finally, place the net pots holding the plants in the holes you drilled earlier. 

That’s it — your NFT system to grow cannabis is ready and running!

Tips for Operating an NFT System

You have set up the system, but it is not a set-and-forget system. There’s always room for improvement, and to help you get there, here are a few tips:

• Test the system thoroughly before introducing new plants, so you understand the workings entirely and don’t risk your first crop.
• As your cannabis plants consume more water, the EC and PPM of the nutrient solution will get disturbed. Therefore, top it up and check the nutrient solution at least once a week.

We recommend replacing the nutrient solution every ten days to keep it fresh and clean for your cannabis plants.

• A pH ranging from 5.5 to 6.5 is ideal for hydroponic systems, but your cannabis plants may love a stable pH between 5.8 to 6.2 in NFT systems. There’s no growing media, so the values may differ slightly. 
• Ensure all channels and the nutrient reservoir are completely light-tight as light can cause algae growth within, which can subsequently cause root rot and clogs within the system.
• NFT cannabis plants can exhibit explosive growth, so give plenty of space to your plants. 
• Only introduce those seedlings and clones with properly established root networks in the system; otherwise, they may fail to feed on the thin film of nutrient solution.
• If your NFT system to grow cannabis is noisy, we recommend using a spreader mat under the channel and reservoir to reduce the noise. As a plus point, it also smoothens the flow of the nutrient solution.

Summary: How to Grow Cannabis Using the NFT (Nutrient Film Technique)

Investing your time (or money) into an NFT system to grow cannabis can be quite rewarding. And the rewards are not only limited to better cannabis buds. 

If you're truly interested in starting an NFT system, we recommend doing complete research before diving into it. In addition, consider going with a commercial setup rather than making one at home if you don't have a lot of experience with DIY projects. This doesn't mean that you shouldn't try setting up a DIY NFT system — you can, because it's easy to do so; however, you should conduct some test runs with a few extra seeds laying around.

Using an NFT system teaches you a lot about how cannabis plants behave, how you can use your nutrient solution and environment to fine-tune your culture, and use a small space to grow bigger plants.

So, whether you are simply experimenting with an NFT system or adapting it for your entire culture, you should go for it. Just remember to research well and be patient when setting up the system.

The results will be worth it.