how to grow cannabis

Introduction To Hydroponic Weed Growing


Growing medicinal grade cannabis hydroponically has become more and more popular in recent years mainly due to the greater control over the growing cycle. By growing hydroponically it is possible to produce a much higher yield and an overall better product compared to growing outdoors or growing in a soil medium. Growing medical cannabis indoors is an attempt to recreate the optimal growing environment that Mother Nature provides. When growing hydroponically it is possible to far surpass virtually any outdoor grow scenario and this translates into what many experts describe as the perfect grow. That being said, keep in mind that hydroponics are difficult to master and while the potential rewards are great, so are the inherent risks. This method is not recommended for first time growers, although everyone must start somewhere. By carefully studying the basic techniques and advanced strategies outlined here, you will be able to produce the highest quality medical cannabis within a relatively short period of time.

How To Grow Weed Hydroponically


There will be bumps in the road, you will have disappointments and mistakes will be made along the way. All of this is to be expected and you should be prepared for it as the better prepared you become at handling these problems, they faster you will acquire the skills and knowledge necessary to harvest your medicine effectively and efficiently. Please do not come into your first hydroponic setup with the mindset that a certain number of plants or a certain size grow room will yield a specific amount of medicine for you, this is simply not going to happen immediately. What will happen is that along with cultivating medical quality cannabis, you will also cultivate a newfound respect for the plant itself and for the skills and experience involved with producing high-grade medical cannabis.

Water Treatment / PH Testing


The reason that hydroponics has gained such an immense following is the yield. Everyone wants bigger plants and a heavier yield. By growing in water, rather than soil, this allows the roots to absorb much more oxygen, water and more importantly, nutrients. The first aspect of hydroponics is getting the water to the right conditions for growing cannabis. This means you want to achieve a ph. of around 6.0, or slightly acidic. For this you can use tap water, bottled, distilled, or filtered water. The optimum choice is reverse osmosis filtered water but these setups are costly and nonessential. Most tap water comes out closer to 7.5 or 8.0 so you will have to lower the ph by adding chemicals. This means using a standard ph test kit like the kind used for testing hot tubs and pools; this will work fine in most applications while costing less than $5. You can also buy an electronic ph tester that is simply placed in your water for a second or two but these pens start around $40 and add to your startup costs.

Marijuana Hydroponics PH

Ph test pens have been known to foul up from time to time and your ph is something that you cannot mess around with. In addition these pens will need to be calibrated from time to time and this can be a bit of a hassle so the pool ph test kit is generally recommended, especially for smaller setups. Paper test strips are also a choice, but while they are cheaper, they may be less accurate because you are matching the color of the paper to the color guide which is sometimes harder than it sounds. Ph test kits for pools and spas consist of a small plastic tube that is typically filled half way with your water, and then simply add 3 or 5 drops of dye generally; the directions will indicate how much of the testing dye is needed from the small bottle included in the kit. Put the cap on the tube and shake it once or twice, then compare the water color to the indicator chart that is usually found on the side of the testing dye bottle. It will help you establish a baseline color reading if you hold the tube up to a light or a white background the very same way every time you test, in order to best interpret the results. It is crucial to the health of your plants that the water temperature remain around 62 – 65 degrees Fahrenheit, or you will likely have problems down the line with root rot or algae buildup.

how to grow weed hydroponically soil

The heat from your grow lights may be the culprit or you might not run the AC that cold like most people, so consider a cooling unit if you are growing in a particularly hot place although water will stay cooler than room temperature for the most part so buying a water-proof pool/spa thermometer for less than $10 is a good idea.

Now you will need to raise or lower the ph to isolate around 6.0 for optimal growth. The best way to do this is to buy PH UP and PH DOWN from your local garden shop or again, the trusted pet store aquarium section.

Note: If you do find yourself in a larger pet store, you may want to spend ten minutes talking with the nerdy expert aquarium guy. This person will help you save time and money by showing you the quality merchandise versus the cheap stuff and help to give you a better understanding of what size equipment you will need for your particular setup. Remember buying air pumps and water pumps with higher output rates is always recommended.

Adjusting Marijuana pH

Balancing your marijuana grow medium’s ph can be a headache when you first begin, so start with a small amount of ph up/down. What works is a teaspoon amount at the most. When you add the ph up/down, swirl the water a bit and allow enough time for the ph to settle. Test again and repeat until you have the magic 6.0. It will save time and money to make a note of how much you added from each bottle so you know for the next time. Most likely your first time will consist of numerous attempts that over shoot the mark but soon you will know exactly how much ph up/down needed for your water and this depends on the number of gallons your reservoir holds. The different nutrients you add will cause changes in the ph level so you may want to add the nutrients first or you can test the ph again after adding, but either way, know that it will change somewhat. Phosphoric acid is the chemical that lowers ph and potassium hydroxide raises it, so if you have a forest in mind, you may want to invest in these chemicals but know that these can burn skin and eyes badly, so use gloves and goggles always.

Hydroponic Marijuana Grow Reservoir Maintenance

When you begin growing you will want to check the ph daily to make sure your young plants do not have to fight stressful conditions to become established. Ph will increase as the plants use up nutrients in the water and the larger the plants, the faster these changes can occur. There are plenty of house hold products that can easily raise or lower ph but they are not recommended for anyone serious about growing medical grade cannabis. In the event that you run out of ph up/down or an emergency situation arises where you must adjust ph, you can lower ph with vinegar, vitamin C, club soda, aspirin, or lemon juice. Raise ph with ammonia, baking soda, or drain cleaner. Generally these home solutions will not last as long as proper chemicals and you are introducing other chemicals into something that will eventually be ingested into your body.

Think about it.

Next you will be adding air to the mix.

Hydroponic Growing Systems – Air Stones / Air Pumps

Your plants cannot survive without a steady supply of fresh air being pumped to the roots and this means you will need an air pump. An air pump is a small device that plugs into the wall and does just what it says, pumps air. A wide variety of sizes are available and depending on how you choose to grow and the size of your setup, you will need to pick a pump large enough to handle the needs of your plants. Most stores that have pet supplies, specifically aquarium supplies, will have exactly what you need to get started. First decide how many gallons of water will be running through your system and this will determine the size of the pump you need. Air pumps will show on the box what the gallon capacity is. Smaller models will only handle 10 or 20 gallons while larger pumps that are primarily used for decorative fish ponds will be able to handle thousands of gallons.

Selecting The Best Hydroponic Equipment

When selecting an air pump you always want to select a unit that handles more than the number of gallons in your reservoir. If your reservoir is 20 gallons, be sure to buy a pump that will handle 40 – 60 gallons. The reason for this is root growth and nutrient absorption requires oxygen-rich water. Keep in mind that these pumps are designed to provide air to pet fish, not cannabis plants so the bigger the better. Your air pump may provide adequate oxygen for the first number of weeks but once you have fully developed roots that are a foot or more in length and width, your air pump will not be able to push fresh air to all parts of the root system. You are striving to achieve maximum oxygenation at all times inside your reservoirs. To oxygenate the water completely you may want to select a dual or quad outlet pump rather than a single outlet pump as these provide you with more options for air distribution. After you have the right size air pump for your setup, next you need to buy clear or black plastic tubing to transport the fresh air into your tanks.

Generally this tubing is sold in 25 foot lengths. Along with the tubing you will need to buy connector fittings and t-fittings to split your tubing and to connect it to the last component of your oxygenation system, the air stones. Air stones come is a wide variety of shapes, sizes and materials. This is one component that most beginners will overlook the importance of and end up paying the price for in root system problems and yield reduction.

Rubber, ceramic, and actual stone are just three of the materials available but what is more important than material is the level of air dispersion that your stones provide. A quality air stone will produce many tiny bubbles that spread out wide to hit as much of the surface as possible while still pushing the air out with enough force to allow the water to circulate properly. Cheaper air stones will let out much larger air bubbles and generally in a small area directly above the stone itself, this will cause “dead” spots in the tank where your roots simply hang limp and do not get as much oxygen constantly. This is where having a dual outlet air pump and some extra t-fittings will come in handy. Use the t-fittings to add as many air stones to a single, dual, or quad outlet air pump as you want. Keep in mind that while having extra air stones does means better coverage, every time you split a line, the result is two air lines that are only half as strong in terms of air pressure.

A good rule of thumb for proper aeration is that you want to see all the roots flowing freely in the tanks like hair in the wind. If some roots are clumping together or sticking to the side of your tanks, these roots may start to rot and cause even greater problems for you down the line. By providing a steady supply of well-dispersed and forceful air to your plants, you will prevent a good deal of root rot and your reservoir will require less cleaning overall. Your air stones will get clogged up as time passes and you need to soak them in a hydrogen peroxide solution about every month or two, and at the very least between grow cycles. You may want to try several styles for your particular setup but air stones will degrade with age and use, so don’t be afraid to replace them as needed.

Hydroponic Weed Growing Tutorial

  1. Mix cleaning solution (1 part Hydrogen Peroxide / 10 parts Water).
  2. Drain your reservoir.
  3. Transfer plants to fresh water.
  4. Check and clean root systems carefully
  5. Using cleaning solution; wipe out reservoir completely, clean inside of lid.
  6. Rinse reservoir with clean water.
  7. Refill reservoir with ph-balanced water, nutrients.
  8. Replace plants

Enhancing Marijuana Growth

growing marijuana in hydroponics

Your reservoir is the place where it all happens. It may look incredible up top, but the real action is happening inside your tanks. The roots are essential to developing healthy plants and to producing a high quality yield. Many beginning growers are quick to forget about the importance of maintaining the reservoirs and the root systems because you simply don’t see them as often as you do the foliage. Your tanks should be cleaned every two weeks or so. This involves draining your water and nutrients which can be done simply dumping the reservoir outside or in the drain but more likely, you will need a water pump and plastic hosing. Supplies for home setups can be purchased for around $25 at most larger pet stores, again just look in the aquarium supplies section where you picked out your air pump and air stones. Water pumps have a rating of Gallons Per Hour (GPH). This indicates the rate at which the water goes through the pump. The higher the GPH, the faster you can drain your reservoir(s) and if you are growing several large plants this can quickly turn into a lengthy task.

By putting a water pump inside each reservoir you can more quickly drain and refill your tanks each week but this will add a bit to your startup costs and inexperienced growers need to be careful when using water pumps and water lines as you can quickly flood a grow room while pumping out the reservoir.hydrofarm  marijuana growing

It may take a few minutes to pump so you feel you have time to attend to something else but if your water line should foul up or come loose, you may find yourself spending hours cleaning up gallons of nutrient solution.When you are installing air lines or water lines, always be sure to make holes as small as possible to block out all light. Light is what grows algae and algae grows very fast so be diligent in checking for problem areas. If algae growth seems to be a recurring problem then you may not have a reservoir with thick enough plastic and some people will surround reservoirs with duct tape or aluminum foil to remedy this if replacing the reservoir is not an option.

Cleaning Your Reservoir

Once you have drained your reservoir, you will want to wipe down the entire surface, including the underside of the reservoir lid. A hydrogen peroxide (H202) solution is recommended for this. Mix one part H202 to ten parts water. H202 comes in a variety of strengths from (3%) to (35%).

It is cheapest to buy the food grade (35%) and dilute that down to a (3%) solution but it can be harder to find and the local drug store stuff works just fine. After cleaning, you want to rinse out the reservoir and refill with ph-balanced water and nutrients. Some growers like to add small amounts of H202 to their reservoirs as often as daily. This can provide extra oxygen to the roots and help reduce the risk of root rot but you will want to be careful as adding too much can cause problems and if you are just starting out, you will have enough to worry about. Your plants will likely have roots that are dead or dying and you will need to carefully pull out the brown, discolored, or slimy roots to prevent rot root when you are cleaning your tanks. It may be necessary to run cold water gently through troubled roots if you suspect a root rot problem is beginning because whatever you miss in the root system cleaning will start to multiply and spread all over again.

marijuana yield hydroponic how to grow weed

It is very important that when you are draining your reservoir, you set all your plants in ph-balanced water. Make sure that the water is the same temperature as your reservoir to prevent shock to the plants. In many places the water running from the tap will be 20 – 30 degrees Fahrenheit higher or lower than the temperature of the reservoir. Make a note of this and have your ph-balanced container filled hours before to ensure this does not happen. Some growers choose to buy multiple reservoirs to make this process easier and faster. The water you have set aside to put your plants in while cleaning your reservoir will probably need to be treated for ph as well.

Cannabis likes a ph around 6.0 as an average and in many places tap water has a ph of more than 8.0 and more than 7.0 in most places. This is a sizable change for your plants to adjust to and then have to readjust as soon as being placed back in your ph-treated solution. Hydroponic nutrients MUST be utilized within the proper pH ranges. Otherwise, nutrient-lock up may occur, and you will be left with crappy, brittle bugs that break at your fingertips!

This becomes less of a problem the faster you can get your reservoir cleaned and refilled, so keep this in mind BEFORE you start draining your tanks and find yourself scrambling to balance ph, add nutrients, clean roots, mix H202 cleaning solution, wipe down reservoir/lid, rinse out your reservoir and finally place your plants back carefully. At some point you may have something pop up unexpectedly during the cleaning process in which you have to leave your plants unattended for longer than you planned for so don’t leave yourself in a position where you are causing added stress to your plants, especially younger plants. You will have a number of different circumstances to deal with when the time comes to clean the reservoir and this depends on what type of hydroponic system you choose to grow with.

Hydroponic Systems For Growing Weed Plants Cannabis Marijuana

There are many variations of hydroponically learning how to grow weed, but the most common used methods are listed below:



The aeroponic system consists of a large, enclosed growing chamber with the plants suspended above it. For the home grower, imagine or use, a large Rubbermaid container. The plants are most often placed into net pots with the roots hanging down into the chamber. Inside the chamber are small sprayers that mist the root systems to deliver the nutrients. A timer is used to turn the sprayers on for a few seconds, every couple of minutes. The number of sprayers is determined by the size of the grow chamber and the root density of your plants so make sure you have enough spray coverage to sufficiently saturate the entire root systems of all your plants. In any hydroponic system if your roots begin to clump together, problems may arise in the form of rot or disease. This system will provide excellent growth but is difficult to master compared to others. Because the sprayers produce such a fine mist, use of organic nutrients is not possible with this setup as they will quickly clog the sprayer heads. Aeroponics systems are also a problem during power outages because the roots will dry out and die extremely fast if the sprayers stop.


The DWC setup, sometimes called a water culture, is probably one of the easier designs to master. Start seeds or cuttings in rockwool cubes; next transfer them into net pots using clay pebbles to support the plant. Other grow mediums are available for this but clay pebbles have consistently proven to be durable and reliable. A reservoir is needed at this point which will be filled with your nutrient solution. This system lends itself nicely to a homemade setup and is a solid choice for the first time grower. Some reservoir options include 5 gallon buckets or Rubbermaid containers but a wide variety of other sealed, plastic containers will work. Be sure to choose something that it the right color (preferably white or black) and has thick enough plastic to keep all light out. With the plants placed carefully into net pots, place the air stone(s) directly under the roots and make sure the net pots are submerged about one inch into the nutrient solution.

Depending on the size of the net pots and how big you want to grow your plants, the depth of net pots can vary from barely touching the solution to being submerged several inches. With no drip lines or sprayers to clog, this system is very reliable but the one drawback is that supporting large plants can sometimes, but not always, prove difficult. DWC systems that devote 50 – 100 gallon reservoirs to one plant have been known to produce unbelievable results under expert supervision. Power outages will shut down your air pumps and although your plants will be ok for several hours, you will need to get oxygen flow back into the roots to prevent crop loss.


The drip system uses a base reservoir and water pump connected to drip lines to provide the nutrient solution to your plants. Plants are most commonly placed into individual plastic pots that are filled with a growing medium such as clay pebbles. A timer is used to control the pump and the nutrients are dripped onto the base of each plant where they trickle down through the growing medium and saturate the root system. The nutrient solution then flows back into the reservoir to be reused. The drip lines can be a problem for organic growers as they are prone to clogging. This system can be highly effective for growers most concerned with low-maintenance. The size of the reservoir will determine how often you need to add more nutrient solution, so using a larger reservoir is ideal for people who want to devote less time. Once experienced with this design it is possible to leave it untouched for a week or even longer, a big plus for some growers.


ebb and flow hydroponic marijuana grow system

Probably the most popular system for the home grower, the ebb and flow (or, rather “ebb n flow” systems) consists of a reservoir containing a water pump, with a single grow tray, or individual grow pots inside a grow tray, sitting on top of the reservoir. The water pump is controlled by a timer that intermittently pumps nutrient solution to flood the tray and once the tray is fully filled, an overflow valve turns off the pump. You will fill the entire grow tray with a growing medium such as clay pebbles, or you can do the same with the individual pots that are sitting inside the larger grow tray. The flood timing of this setup is the key to proper growth. Depending on the rate that the nutrient solution drains back into the reservoir, you can set the timer to fill the tray every hour or only a few times a day but most setups will flood for about 15 – 20 minutes, every 2 – 3 hours. This system is fairly reliable but can give you problems due to power outages and pump or timer failure.



Commercial growers generally prefer this method for growing cannabis on large scale operations. For this design, a long tube made from plastic/PVC or a flat-bottomed, light-proof plastic material, has a number of holes cut into the top of it along the entire length. This tube is placed at a slight angle to allow the nutrients to flow into one end and uses gravity to carry them the length of the tubing to be collected. A large reservoir containing nutrient solution pumps a constant, shallow layer of nutrients (film) down these tubes and when it reaches the other end, it then drains back into the reservoir to be recirculated. A thin mat can be used to line the bottom of the tubing to allow for more even nutrient flow, called a capillary mat. The placement of the plants at intervals along the tubes must be far enough apart to avoid the roots systems growing into each other entirely. This setup generally does not require using grow medium but rather has the plants in net pots dangling freely into the tubes. With no drip lines or sprayers to get clogged, organics are a go for this system. Again power failures and pump failures will cause immediate problems because the roots become exposed to air only and will dry out in minutes flat. It should be noted that plants will require adequate root systems before going into the NTF setup to ensure they receive enough nutrient solution. Another option is to add drip lines to small plants to encourage root growth.


wick system hydroponics growing weed with soil

The wick system is the most basic hydroponic design. A grow tray filled with a growing medium, such as rockwool cubes or clay pebbles, sits on top of a reservoir. The reservoir is filled with nutrient solution and an air pump that provides aeration. Several wicks connect from the reservoir and run up into the grow medium to provide nutrition to the root systems. These wicks slowly absorb the nutrient-rich water and release it into the grow medium where it is absorbed by the plants. This is known as capillary action. In order to provide the necessary nutrients, two or more grow mediums of different sizes can be used in the grow tray. While this system is easy to operate and maintain, its major drawback is that it cannot provide enough nutrients to support larger plants, but for many home growers only needing small to medium sizes crops, this can be a very simple and easy-to-use design.

Hydroponic Nutrients

growing weed









Nutrients are the foundation of your medicine. What you put into your plants is what you get out of them. That being said, the first decision is organic versus chemical nutrients. The recent boon in the organic growing industry has changed the way many people shop for food or in this case, grow their marijuana. Organic nutrients are overall more costly, but the results can be some incredibly powerful medicine. The overall taste is almost always better and organics provide that little something extra from Mother Nature that simply produces a better finished product when compared to chemically grown marijuana. While organics may provide a superior product, the downfall is that the yield is typically not as high as what chemical nutrients will provide, given the same conditions.

That is not to say that it can’t be done, but most experienced growers will agree that chemical grows give you bigger, faster growinghydropomnically plants as well as heavier yields. Many medical marijuana growers, who provide for themselves, choose organics because they have the time, patience, and money to do so. If you choose to start with strictly organic nutrients for your medical grow, you may want to consider a soil grow first, as this will tend to minimize the risks to your plants that are associated with some of the techniques used in hydroponics. By using chemical nutrients you are not doing our beloved planet a whole lot of good because the excess salts and leftover chemicals you will be pouring into the local water supply have a negative impact on the environment in many ways.

It is easy to say, “I am only one person, it can’t be that bad,” but please remember the number of medical marijuana patients is growing extremely rapidly and while that statement may be somewhat true, you are going against a lot of what the cannabis culture stands for. The knock on chemical nutrients is that they will adversely affect taste and the chemical residue can be transferred to your body. Keep in mind that most, but not all, commercially grown and sold marijuana is produced with the intent of making money more so than delivering the highest quality product possible whereas medical marijuana patients are only growing enough to supply themselves.

What this means is that commercial growers using chemicals may shorten or even eliminate the flushing cycle all together in order to get the product out faster and begin a new crop sooner. A flushing cycle is the final stage before harvest where your plants receive no nutrients or a small amount only. Marijuana smokers will confirm that most commercially sold crops leave black ash that must be relit repeatedly and this is due, in part, to trace chemical residue from the chemical nutrients used during growing.

Chemical nutrients will provide you with a larger yield, especially for new growers, a faster growth cycle, they are less expensive, easier to deal with in many cases, and are less likely to clog your system or cause disease and root rot. With a proper flushing cycle, the vast majority of chemical elements will be removed from your plants. The question of organic versus chemical nutrients is causing a good deal of controversy in the marijuana community, with many enthusiasts refusing to touch anything not 100% organic and even turning their noses up towards those using chemical-based nutrients. Make sure to take into account all potential factors such as harvest size, potential health factors, environmental damage, cost, ease of use, and system type when selecting your nutrients. The best idea for starting out may be to use the best of both worlds. Try using some chemical nutrients and some organic nutrients to give your medicine a fuller flavor but also to ensure you are providing enough marijuana for your medical needs because, after all, if you run out of medicine then you will likely be buying chemically grown commercial marijuana and that often times funds individuals known to do worse things than put small amounts of chemicals into the earth.

Over time you will fine tune and hone your skills to develop a feel for what is appropriate for your situation.

Hydroponic Nutrients Marijuana Grow

Plant nutrients are further divided into two main categories known as micro and macro. There are six macro nutrients that you must supply your crop in order to have success. The first three: nitrogen (N), phosphorus (P), and potassium (K); make up the primary nutrients. These are the three elements needed most for growing anything and they represent the number system used on all fertilizers and nutrients, known as the NPK ratio (e.g. 20-20-20). The secondary nutrients are calcium (Ca), magnesium (Mg), and sulfur (S). These nutrients are equally as important but are needed in smaller quantities than the primary macro nutrients. The seven micro nutrients are also essential for healthy plant growth but are required in only trace amounts. The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn). By selecting a comprehensive base nutrient with a ratio around (1.0-1.5-1.0), you will be providing all the necessary macro and micro elements to your plants. This will be something that is fed to your crop for the duration of the growth cycle.

There are two phases to growing marijuana; the first is the vegetative cycle in which plants grow roots and foliage while putting on size. The second is the flowering phase that produces the buds that will become your medicine. Different levels of nutrients are needed during these cycles in order to achieve the best results. In the vegetative state, cannabis plants need more (N) and (P); and in their flowering-stage (P) and (K) are demanded in higher quantities. The exact levels and the timing of the nutrient feeding schedule is one of the most heavily debated topics in the marijuana growing community worldwide. Ten different growers will tell you ten different feeding schedules. Due to the huge variety of marijuana strains and the diverse genetics associated with them, you can safely say that no two plants will be exactly alike in terms of precisely what they need to achieve the best results.

Growing hydroponics allows the upmost control over the level of each nutrient. By using a TDS meter, you will be able to measure the Parts Per Million (PPM) of your nutrient solution. The ppm is the ratio of nutrients to water in your nutrition solution. The following chart illustrates a ppm schedule for a one month vegetative cycle and a two month flowering cycle. You will need to carefully select a combination of nutrients to provide complete micro and macro in the proper ratios. The levels of each nutrient will increase or decrease throughout, depending on what stage of growth your plants are in. Many growers choose to use a simple three part formula (Vegetative, Micro, and Flowering). On top of these three major components, you have countless options to supplement with, such as rooting hormones, microbe producers, finishing product, foliar sprays, and flavor enhancers, just to name a few. Depending on what brand of nutrients you choose to use, the ratios needed for each cycle will be different but all nutrient companies will provide a guide for the proper ratio to use during each week of the growth cycle. A baseline guide for a typical twelve-week grow cycle is shown below.

Week PPM

  1. 500-600
  2. 800-900
  3. 1000-1200
  4. 1200-1400
  5. 1200-1400
  6. 1200-1400
  7. 1200-1400
  8. 1400-1600
  9. 1400-1600
  10. 1400-1600
  11. 1400-1600
  12. 1400-1600

Until next time,

Keep it GREEN, keep it LOVING and full of LIGHT.