What Is Hydroponic Weed? [Beginner’s Guide]

Every beginner grower needs to know this

The term ‘hydroponics’ is a Latin term that translates to ‘water working.’ In terms of growing weed, it relates to the process of producing the plants in highly oxygenated water that is enriched with additional nutrients. In basic terms, hydroponic marijuana is cannabis that is grown without soil. There are several ways to grow weed hydroponically. You can suspend the roots of your plants in Rockwool, clay pellets, water, coco peat, sand, or gravel.

Regardless of what you use as a growing medium instead of soil, you have to apply a nutrient-laden solution to the roots. The water that isn’t absorbed by the roots gets recycled through the system for later absorption.


A Brief History of Hydroponics

The Hanging Gardens of Babylon was one of the Ancient World’s Seven Wonders. Theories of where and when they grew vary. One version suggests that Babylonian King, Nebuchadnezzar II, created them in the early 6th century BC. Another story credits Assyrian King Sennacherib, who built the Gardens in the early 7th century BC in Nineveh.

Regardless, the gardens were potentially created using hydroponic methods. It is also likely that the Aztecs used hydroponic techniques at Lake Tenochtitlan in the 10th century AD.

In the modern era, this form of growth has helped create some of the world’s best marijuana strains. As cannabis cultivation has increased, improvements in hydroponics have emerged. Although there are many different forms, several of which we look at below, hydroponics is ostensibly the practice of using soilless systems to grow plants.

What Is Hydroponic Cannabis?

hydroponic marijuana

Hydroponic marijuana refers to a means of growing using a soilless hydroponic system. In other words, you cultivate plants using an inert growing medium and nutrient-rich solutions. Previously, the assumption was that hydroponic setups were complicated and expensive affairs designed solely for commercial growth. In reality, however, you can engage in weed growing with hydroponics using something as simple as a few pots that contain the inert medium. By all means, you can opt for a more complicated option, but it requires significant setup time and a ton of maintenance.

Growing cannabis hydroponically has become an increasingly popular method because of the issues associated with using soil. It is a much better option for indoor growers who face the following problems when growing weed ‘traditionally’ using soil:

  • A constant need to monitor the pH of the soil
  • Ascertaining the correct level of nutrients is hard
  • There is always a potential problem with pests
  • You might not be able to recycle the soil you use
  • You have to choose the best soil because its quality dictates the size and potency of your final product.

A Balancing Act

The biggest hurdle to overcome by using soil is nutrient intake. Organic matter decomposes in soil and then breaks down into nutrients such as Nitrogen (N), Phosphorus (P), and Potassium (K). The nutrients are dissolved in water and absorbed by the plant’s roots.

Everything needs to be balanced perfectly in the soil if you want your marijuana plant to get the ideal nutrient intake. When using soil, you have to contend with biological imbalances, insufficient organic matter, and contamination, which makes perfect balance an impossibility. With a hydroponic system, you can provide cannabis with the right nutrient balance and ensure that it goes straight to the plant’s roots.

Overall, soil loses a lot of nutrients, and it is difficult to measure its pH. When you use a hydroponic setup, it is much easier to determine pH and adjust as necessary. In soil, you can only dissolve the nutrients when you water your plants.

When you grow weed hydroponically, everything is dissolved in water automatically, ensuring there is always plenty of moisture. Also, as these systems are sterile, you reduce the threat of pests significantly.

Hydroponics Nutrients

With a hydroponics setup, you are responsible for providing the plant with all of its nutrients. If you get it wrong, your plants will die or produce a small and unsatisfying yield. On the plus side, a hydroponic system ensures that your marijuana plants’ roots easily find nutrients and don’t waste energy looking for them.

All hydroponic systems must provide oxygen, water, and a host of nutrients to marijuana plants. Nutrients include:

  • Nitrogen
  • Phosphorus
  • Potassium
  • Calcium
  • Magnesium
  • Sulfur
  • Iron
  • Chlorine
  • Manganese
  • Boron
  • Zinc
  • Copper

Nitrogen, Phosphorus, and Potassium are the essential nutrients, however. Most solutions contain 15% of each, also known as a 15-15-15 solution. If you grow weed in temperatures below 80 degrees Fahrenheit, you need higher amounts of nitrogen. Other possible solutions include 20-20-20 or 23-19-17.

During the flowering process, increase the level of potassium so that it comprises at least 20% of a solution. Be wary when fertilizing the plants, because too much kills them while too little slows growth. When your reservoir’s water level gets low, add three-day-old tap water. It is also a good idea to change the nutrient solution every two weeks and use hot water to clean out all the equipment you use, especially the pumps and reservoir.

PPM & EC Considerations

It is common for nutrient solutions to be deficient in magnesium. If this is the case, use Epsom salts. Depending on your crop’s growth stage, it is necessary to adjust nutrient levels to optimize growth. It is also important to change your solution regularly to avoid nutrient deficiencies. When checking the pH, be especially wary of it becoming more acidic because of cationic exchange.

You should be easily able to find nutrients for your hydro growing system online or in a gardening store. They tend to come in a pre-mixed liquid or powder form. The powder is less expensive, but liquids mix with water more efficiently and are ideal when growing smaller crops.

When adding nutrients to your marijuana plants, take pH and EC (electrical conductivity) readings. The EC rating measures mineral content, the more minerals there are, the higher the EC reading. Typically, an EC rating of 0.8 – 2.0 is apt for growing weed. As you’re probably aware, younger plants require more nutrients than a flowering plant.

We mentioned PPM measurements above, but let’s go into greater detail. In the industry, there are ‘500’ and ‘700’ scales. You multiply the EC rating by either 500 or 700, depending on the measurement you’re using. For instance, with the 700 scale, an EC reading of 1.5 converts to 1050 PPM (700 x 1.5), but it would be 750 PPM with the 500 scale (500 x 1.5).

As we mentioned earlier, the ideal PPM depends on the growth stage. Here is a quick guide:

  • Seedlings: 100 – 250
  • Early Vegetative Stage: 300 – 400
  • Late Vegetative State: 450 – 700
  • Early Blooming Stage: 750 – 950
  • Full Bloom: 1,000 – 1,600

Setting Up Your Hydroponic Cannabis Growing System

There are several hydroponic gardening systems to choose from, and all of them are suitable for growing cannabis indoors. Regardless of the method you use, the overall tactic involves the use of a reservoir containing the nutrient solution. You then place it beneath a growing tray. This tray holds the inert growth medium of your choice, such as sand, gravel, or Rockwool.

hydroponic marijuana

Hydroponic weed involves growing the plant in the medium, where it develops a set of roots and a stem. The roots grow through the medium and into the nutrients, and you use a small pump with a timer to fill the bottom layer with the nutrient solution. After an allotted period where the plants are fed and watered, the timer shuts off the pump, and the solution drains back into the reservoir.

The hanging root structure of the plants means they are exposed to air constantly, and the result is a crop of flourishing plants. Your cannabis plants can use their energy for the sole purpose of maximizing growth. With soil, they waste energy trying to find air, food, and water. This is why weed grows so spectacularly in a well-designed hydroponics garden.

There is a multitude of indoor hydroponic systems to choose from, but we will only focus on the best known.

Types of Hydroponic Systems


This is a unique method because you don’t use a growing medium. Most growers tend to use a tiny amount to root a cutting or germinate the seed, however. The roots of the marijuana plant are suspended mid-air inside a chamber kept at 100% humidity. You must use a fine spray filled with nutrients.

This form of feeding enables the roots to absorb large amounts of oxygen. As a result, the plant can grow up to 10 times faster than it would in soil, with practically no water loss through evaporation. If you use this method, be wary of clogged misting valves as they could prevent moisture from getting to the roots; this will kill your plants.

Deep Water Culture (DWC)

This is one of the most straightforward hydroponic systems to use, which makes it ideal for beginner growers. All you have to do is put the plants in separate containers and place each one in a grow tray that gets suspended in water. Your water tank will have an air pump that ensures the water remains oxygenated, and you add nutrients to the water to feed the roots. Although you submerge the roots in water, the oxygenated air pumps ensure they receive ample oxygen.

Drip Irrigation

This is a popular commercial option because it saves a lot of water. You need to place small droppers beside the roots of the plant, which are in pots containing the growing medium. Little drops of this nutrient system drip out regularly and feed the plant. It offers a low level of evaporation, and, as it is silent, it is perfect for a clandestine operation to keep your grow area protected from thieves.

Ebb & Flow

This is different from several hydroponics systems because it does not involve the continuous submersion of the roots in water. It works similarly to an ocean tide, as it fills a tray with oxygenated water and treats the plants and growing medium. When it is full, the pump switches off, and the solution drains back down into the reservoir. It stays there until you are ready to flood the garden again.

Nutrient Film Technique (NFT)

NFT is a complex system and involves pumping your water solution from the reservoir to your planting tube. It is common to use large PVC tubing angled at a slight decline. This tactic ensures that, when the water drains down the pipe, it passes by the roots of all marijuana plants before it gets recycled in the container.

One of the most significant problems with this system is that the water solution could fail to leave the tube, stagnate in the channel, and kill your plants. This is why you need to make sure the tube is cut at a steep enough angle to allow for easy passage of the water.

Wick System

This is another easy-to-use system. It works like a DWC system insofar as it uses a material such as a length of rope through a PVC tube. You pull the solution up the line and place it in the tray. With the wick system, you don’t need to bring the water to the plants. Although it may not result in plants that grow as quickly as they would with more complex systems, it is the ideal way to learn hydroponics through practice.

What Are the Most Common Hydroponics Growing Mediums?

While there is a wide range of growing mediums, five of them stand out. Please note that each option varies in its ability to retain water and allow oxygen in.

Clay Pellets

Although they are light enough to work with efficiently, clay pellets are still sturdy enough to support marijuana plants, and they are reusable! They wick moisture up to the roots and enable oxygen to flow through due to the size.


This medium is popular because it retains moisture exceptionally well. It consists of thin rock fibers developed by heating rock to very high temperatures and spinning it into tiny threads. If you purchase Rockwool as a hydroponic growing medium, soak it in a solution with a pH of 5.5 for up to 12 hours. Make sure its pH is between 5.5 and 6 before use.

Coconut Fiber

This is a more environmentally-friendly option than Rockwool because these fibers come from waste products. As well as retaining moisture and allowing in more oxygen than Rockwool, coconut fibers contain hormones that keep infection and disease at bay.


This porous white substance retains and wicks moisture exceptionally well. Generally speaking, you should purchase large chunks rather than small granules. The surface of each perlite particle is covered with tiny cavities – the result is a vast surface area that holds nutrients and moisture. It is a sterile substance, so there is no danger of pests, insects, or disease.


This is another crushed volcanic rock medium like perlite and is also known for its terrific drainage. Although it is sterile, vermiculite is not generally used as a growing medium by itself, with growers electing to mix it with perlite. If you decide to use it, ask the seller where they got it from, as vermiculite that comes from Africa is very alkaline, with a pH of up to 9.0.

The Pros & Cons of Hydroponics


  • It allows for higher yields from smaller growth areas.
  • Almost total control over the growing process, which typically means better quality cannabis.
  • Weed grown using hydroponics matures faster, and experienced growers can complete six crops in a single year.
  • As there is no soil involved, you don’t have to worry about a myriad of pests, which means no need to use pesticides.
  • Assuming you monitor everything correctly, there is a lower risk of water stress than with crops grown in soil.
  • As you have full control, you can even tailor feeding schedules to the needs of a specific plant.


  • You won’t get your hands on a decent quality system for mere pennies. If you are a recreational grower, this kind of system is probably more trouble than it’s worth financially.
  • Although you reduce exposure to disease, there is a unique danger associated with waterborne plant diseases. They spread incredibly quickly and are extremely difficult to remove.
  • Barring the Wick and DWC systems, it is a complicated process that requires knowledge and patience.

What About Additional Equipment?

Be aware that proper hydroponics gardens require a significant amount of equipment. You can, of course, choose a simple system to minimize what you need, but for the best results, it is worth investing in measuring instruments. Remember, useful hydroponics growing involves constant monitoring of nutrients so you can quickly correct imbalances. As a result, you should strongly consider investing in a pH and PPM meter.

  • pH Meter: In general, most marijuana strains grow best hydroponically with a pH level of 6.0. With a pH meter, you can measure your nutrient solution’s pH daily to keep it at an optimal level.
  • PPM-EC Meter: This measures the water’s electrical conductivity, which is higher when more minerals are dissolved in the water. With this meter, you can prevent under- or overfeeding.
  • PPM-TDS: This is a more sophisticated meter that measures the amount of plant food in the water. If you want an accurate PPM measurement, measure your water’s PPM level, add nutrients, and measure again.

Overall, you should keep the pH level between 5.8 and 6.3, although you will get away with a range of 5.5 – 6.5. As for PPM, make sure the range is between 900 and 2800 depending on your marijuana’s growth phase.

You should be able to find so-called ‘plug and play’ hydroponic systems that provide everything you need to get started. Even so, here is an essential list of things you’ll need for a starter system:

  • One large (3 – 5 gallon) bucket per plant
  • A water pump
  • An air pump
  • A reservoir tank
  • An air stone
  • A grow table
  • A growing medium such as Rockwool or clay pellets
  • Plastic tubing
  • A drip line and up to two drip line emitters for each plant

Tips for Growing Your Hydroponic Cannabis

It should go without saying that using a hydroponic growth system is very different from traditional methods of growing weed indoors. As a result, there are a few things to consider when trying to grow marijuana plants in a hydroponic garden system.

Sterile Equipment

It is impossible to overstate the importance of using clean equipment at the very beginning. All tanks, reservoirs, filters, pipes, and other equipment must be sterile to prevent the development and spread of bacteria. Although hydroponic systems are less susceptible to diseases, they will run rampant if left unattended. It is a good idea to have multiple bottles of hydrogen peroxide and isopropyl alcohol on hand to disinfect your equipment.

Water pH

Make sure that pH neutral water at 7.0 is circulating through your hydroponics system. You can create a reverse osmosis (RO) method to generate and provide pH neutral water. Alternatively, purchase distilled water until you’re able to develop the RO system.

Temperature Considerations

It is best if the water flowing through your system is at a temperature of 65 degrees Fahrenheit. This is the ideal temperature for nutrient absorption, and it also prevents algae buildup. As for your growing room’s temperature, keep it at 75 degrees Fahrenheit, to begin with.


When growing pot indoors, maintaining the right humidity levels is a constant challenge. You have to begin with relatively high humidity and dial it down as your plants grow. As seedlings and in the vegetative state, keep the moisture in the 60-70% range. Reduce by up to 5% weekly until it is at around 40% during the blooming stage. You may need to purchase a humidifier and a dehumidifier to achieve these targets.


There is no ‘right’ lighting setup, only the best one for your grow space and budget. For example, if you have a large room with excellent ventilation and airflow, you can purchase High-Intensity Discharge (HID) lights.

If you have a smaller growing room, try Light Emitting Diode (LED) fixtures or Compact Fluorescent Lights (CFLs) if you have a more modest budget. Overall, choose lighting that produces a sufficient amount of light between 400 and 700 nanometers.


Good airflow helps keep temperatures at the right level. Invest in a few fans and place them strategically in your growing room.

Keep Records

Regardless of whether this is your first grow or you’re a veteran, it is essential to keep detailed records of your crop’s growth. It is not unusual for novices to enjoy spectacular success, only to realize that they failed to record any data. Important notes include pH levels, planting dates, EC measurements, temperature, and humidity.

Final Thoughts on Hydroponic Marijuana

There is a lot to like about hydroponic marijuana. It enables you to grow a lot more weed per annum, and you only need a relatively small growing area to get started. It lets you grow high-quality cannabis in areas where you usually can’t grow in soil. There are fewer pests, and the overall quality of well-produced hydroponic weed is exceptional.

However, it is a tough skill to master, and the initial set-up costs are considerable. If you fail to keep the grow area wholly sanitized, your entire crop could succumb to disease in double-quick time. It is not something you can learn overnight, but if you have the time, money, and patience, learning how to grow weed in this way could yield tremendous dividends. However, I don’t recommend it for recreational growers, as it works best when cultivating large amounts.

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