Whether you started with soil growing indoors or outdoors, hydroponics might be your next great cannabis adventure. Some cannabis enthusiasts say it’s just as easy as soil growing, but others argue it requires more labor and monitoring.
Overall, many indoor growers would say hydroponics is what you make of it, and the amount of time, effort and money you put into this form of growing will show in your crop.
Growers who prefer weed grown from hydroponic methods generally believe that hydro-grown cannabis is more potent and clean than weed grown in soil.
What exactly is hydroponic cannabis growing?
Hydroponic cannabis growing depends on delivering nutrients to a plant’s roots via oxygen-rich, nutrient-rich water instead of soil. In Latin, “Hydro” means water and “ponics” means works. Plants need nutrients and micro-elements, but they do not necessarily need soil as a source of nourishment.
When growing in soil, plants have an extensive root web for absorbing nutrients. If you pull a plant (cannabis or other similar growth) out of the ground, you will notice a complex system of thinner secondary or adventitious roots in addition to the thicker primary root.
When plants are grown in water, they don’t have to rely on this adventitious root web and therefore it’s not needed. Similarly, cannabis plants can absorb the nutrients through the main roots constantly in water as they also absorb the nutrients in the air. The macroelements that cannabis plants need are nitrogen, sulfur, calcium, potassium, phosphorous, and magnesium.
The Pros and Cons of a Hydroponic System
Pros: Many growers prefer hydroponics over soil growing because it produces a higher yield and increased speed of growth. Some argue the buds are more flavorful and potent, but many soil growing fans also claim they can produce flavorful buds. Other advantages include controlling the pH and nutrients more easily than soil.
Fluctuations in chemical balances present a huge challenge when soil growing, but hydroponic growing allows the grower to have more control over levels. This method offers those who must grow indoors a discreet option. Plus you don’t have to worry about moving around heavy bags of soil.
Cons: Some say the cons include potentially hazardous chemicals or heavy metal fertilizers used. Other concerns include the perceived higher costs of hydroponics equipment, but one could argue that you can spend as little or as much as your wallet will allow regardless of the mode of growing.
Another concern is the threat of algae developing in the solution. However, indoor growers can reduce algae through close monitoring and proactive cleaning of equipment.
Growers considering hydroponics may want to evaluate the potential growing space to see if it’s suitable for setting up given the need for access to a faucet, a clean area in which lighting can be controlled. In addition, you also want to make sure you are growing in a secured area.
If you’re growing in a state with authorization to grow for legal medical and recreational use, it must be done in an enclosed, locked space.
How to Set Up a Cannabis Hydroponic System
One of the most intimidating things for a newcomer to hydroponics is setting up. You can keep it simple, and then refine your process with each grow cycle. If you want to keep things manageable, start with an ebb and flow method, which is the first method discussed in the section on various growing hydroponic techniques.
If you plan to pursue hydroponic growing, consider investing in many of the items on the following list. You may already have some of these items if you have already attempted indoor soil growing previously.
Indoor Growing Equipment List:
- Lighting (LED, HID, metal halide, etc.)
- Ventilation fans
- Temperature /humidity gauge
- Oscillating fans
- PPM meter
- pH meter
- Additives and nutrients
- Filters for odor control
- Scissors and trimmers
- Dry nets
- Digital Scales
- Reservoirs, pumps, and tubing
- Growing medium (containers made of rockwool, coco coir, vermiculite, peat moss, clay pellets, or perlite)
Of course, you’ll also need water, and the more accessible and efficient your access to a faucet and drain, the easier your growing experience will be. It also goes without saying that you should have a designated area conducive and clean for growing just as you would for indoor growing. Any kind of cannabis is an investment of time, energy, and money, so the fundamentals of set up go a long way in producing quality weed.
Different Techniques of Hydroponic Systems
Some growers categorize the many hydroponic variations of growing into three main techniques: recycling, run to waste/drain to waste (RTW or DTW), and wick systems. The following information should help you decide which method might be best for you.
The Ebb and Flow System, also known as the Flood and Frain, is considered one of the more popular and easier methods. The roots are flooded for a short amount of time with the help of a water pump that pushes the nutrient solution into the plant tray at regular intervals. This action also pushes oxygen up to the roots. Then it is drained away, and the roots are temporarily dried out.
This drying phase allows the roots to oxygenate. You can place the plants in pots or directly into the porous medium. Suggested medium containers include clay pellets, Rockwool or Coco coir. The roots grow through the medium and down into the nutrient solution.
When using this approach, choose a reservoir that will hold enough nutrient solution for two weeks. Plan to rinse the reservoir out every two weeks and add fresh solution at this point. Check root lengths every two weeks so there that there isn’t a possibility of clogging the reservoir.
You should use a lid on the reservoir to prevent evaporation of the solution, but make sure to monitor the level and add additional solution as needed.
The beauty of this method is its simplicity. You only need a few essential items (a reservoir, a submersible pump, a plant tray, and a timer) in addition to lighting, a tent, and other basic pieces of equipment, making it a good method to try before attempting other more expensive hydroponic methods.
Some growers suggest getting a second reservoir to store tap water for 2-3 days; this step allows the chlorine to evaporate and thus neutralize the pH. Most growers set the pump to turn on every 20 minutes to submerge the roots of the plants.
The Nutrient Film Technique (NFT) is similar to ebb and flow in that they both use water pumps to deliver the nutrient solution to the roots, but NFT is a constantly flowing system. It is also known as the Continuous Flow system. Plants grow in a slightly tilted tray and nutrients are pumped into the higher end and flow to the lower end of the tray back to the reservoir with the help of gravity.
The roots are partially exposed in the recirculating solution, so the roots are in a solution stream which is about a half-inch deep. Growers recommend about 1 liter of solution flowing per minute. That might sound like a fast rate, but it is actually slow and perfect for feeding nutrients to the roots.
You can use either an aquarium pump or a pump made specifically for this purpose. There is no room for error with a continuous flow system, so if there is a disruption of some sort, your plants are at risk.
Make sure your pump is powerful enough to ensure that maximum oxygen makes it to your roots; sometimes a weaker pump means the solution will lose some oxygen en route to the root.
If your pump gives out, your plants will suffer, so either frequently check on your setup or invest in a water sensor. That way you are alerted if you need to replace or fix the pump.
Similar to the ebb and flow method, you’ll want to change the nutrient solution every two weeks for maximum nutrient absorption. Another concern is the potential for the roots to block the flow of nutrient solution, so check the amount of space the solution has to pass through the tray.
You can build your own NFT system or buy a pre-made one. Many growers like the Gro-Tank. Overall, NFT Is one of the more efficient and low-cost methods.
Deep Water Culture (DWC) System is also known as “Bubbleponics” because it uses containers filled with air, nutrients, and water called bubblers. The bubbles ensure a significant amount of oxygen is pumped to the plant roots, which are completely submerged in the nutrient solution. This approach speeds up the grow time.
Expert growers advise maintaining the temperature of the water around 65-68 degrees through the help of a water chiller. This will help keep the oxygen levels in the nutrient solution ideal as it is carried to the roots. Also, monitor the level of solution. Keeping it at the root crown is ideal. Too far up the stem may be overwhelming for the plants.
Run to Waste/Drain to Waste RTW/DTW (non-circulatory system)
Some growers swear by Run to Waste Systems which are also called Drain to Waste Systems. They allow you to have extensive control over what your plants get in terms of nutrients. When using a RTW system, you can place the roots directly in the solution or in a medium like clay pellets or coco coir. Some growers like to give fresh water every 9-10 days to prevent or reduce nutrient buildup.
It’s a relatively simple and inexpensive system to set up. It is also a good system for busy people. If you have to go away for a few days or even up to two weeks, this system can run efficiently and safely. However, most growers advise having a friend check on your grow operation if you will be out of town.
Nothing is more disappointing than spending weeks preparing for a good crop only to return home after a vacation or business trip to find dead cannabis plants.
You can also use a drip system with a DTW system as well as other systems. Drip Systems feed individual plants nutrients through a dripper. It can be set up in the same fashion as a run to waste system, but some growers also rig it as a recirculating or recovery system so they can reuse the nutrients. This technique requires a reservoir tank that holds the nutrient solution, a large tube that runs the solution to smaller tubes that descend to the plants.
This approach is a hybrid of a run to waste system. Smart/Autopot systems involve feeding nutrients through a gravity valve. The nutrient solution tank is higher than the plant. The autopot is placed in a tray and a tube extends from the nutrient solution tank to the float switch valve. Experienced growers suggest giving plants a healthy start by top feeding them twice a day for the first two weeks.
This strategy will also prevent low moisture in the media during this stage, which can be a challenge of the autopot method. Using a root stimulant is also advised during this early stage.
It’s much simpler than other systems, but there are also drawbacks. You don’t need timers and pumps with an autopot, but this also means you do not have anything aerating your water. Roots may be susceptible to root rot if warm temperatures causing oxygen starvation.
Growers who have used the various hydroponic systems claim that this method does not allow for as much control over nutrient flow as other systems.
No flushing like in other hydroponic systems means salt can build up in the medium that you use. One strategy to prevent salt buildup is to flush the pots with water once in a while, but this isn’t always efficient.
Grow Lighting and Light Cycle Considerations
You’ll need reliable lighting and a timer to control the amount of light the plants receive. Some lighting choices include LED, high-intensity discharge (HID) such as high-pressure sodium, or metal halide. LED lights have become popular in hydroponic growing because it reduces heat and uses less electricity.
LED lights are also more effective for all growth stages, whereas metal halide is mainly effective in the vegetative phase.
Hydroponic growing should follow the light cycle recommendations for cannabis soil growing for that specific cannabis strain. Here are the general lighting recommendations: During the germination phase, provide lighting for 16-18 hours a day. Increase lighting to 18-24 hours a day during the vegetative phase. During the flowering stage switch to 12 hours of light.
General Recommendations for All Hydroponic Methods
- Make sure your grow room is as clean as possible. Reduce any harmful pathogens that might be brought on shoes or other items.
- Before starting a new growth cycle, clean your equipment. For example, some growers suggest a water conditioner for DWC systems that removes the mineral salts.
- Adjust nutrients to the stage of growth. Many experts recommend powder nutrient mixes so that you can adjust measurements during each growth phase. Plus, these powder solutions are cheaper than pre-mixed solutions.
- Keep the pH between 5.5-6. To ensure proper testing, buy a pH test kit. If you are using a powder nutrient solution, make sure you let it settle for about 5-10 minutes to get an accurate reading and then take a small sample to test for pH. If you do have to adjust the pH level, you will add products like pH Up and pH Down (acidic) to your nutrient solution. Wait 5-10 minutes to let the pH levels adjust and then retest level before adding the nutrient solution to your system.
- Many growers take notes on dates of nutrient solution changes, problems with equipment, and other notable events. This information is important for the growth cycle and for your development as a grower.
- When your plants are ready to harvest, you can use the same methods that you would after the harvesting cannabis plants grown in soil.
Note: Some hearty, novice-friendly strains include Northern Lights, Silver Haze, Jack Herer, White Widow, and Bubba Kush.
If you’re just starting out as an indoor growing and choose to start with hydroponics, you’ll make no more or less mistakes than you would if you decide to start with soil growing. It’s just a matter of choosing the right hydroponics approach for you.
Part of the fun of growing is learning from mistakes along the way, but nothing’s better than the sense of accomplishment knowing you can grow your own cannabis supply. You can always improve upon your practice in the next grow cycle.