Hydroponic Marijuana Grow Guide

This is a complete guide on growing marijuana hydroponically. We’ll guide you every step of the way for best results!

What is Marijuana Hydroponics?

If you plan to grow marijuana with hydroponics this means you’re going to grow the plants in a bathtub or flow of highly oxygenated, nutrient enriched water. Instead of growing marijuana in soil, you’re growing it in an inert, sterile growing medium such as:

How to Grow Marijuana with Hydroponics

Once you’ve chosen your growing medium you must ensure you’re growing a healthy plant by providing all the nutrients requirements necessary. The plants nutrients will be supplied once you’ve mixed the water with the nutrient solution.

Hydroponics will introduce the water, nutrients and air to the roots via your chosen growing medium. You’ll get quicker results growing your plants hydroponically because you’ll bypass the web of roots and the energy which the plants require to obtain the nutrients, meaning you grow healthy, high quality plants quickly!

It’s important to consider that your plants entire atmosphere needs to be controlled within its growing environment in order for them to be healthy. It’s not likely that you’ll lose much water from your plants to evaporation when they’re grown hydroponically.

Bear in mind that plants are 80 – 95% water, the rest of the percentage is carbon, oxygen and hydrogen, your plants will extract these elements from the air and water.


Plants do not necessarily have to live in soil to survive, they require macro elements nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S). The micro elements required are iron (Fe), chlorine (Cl), manganese (Mn), boron (B), zinc (Zn), copper (Cu) and molybdenum (Mo).

Hydroponically growing your marijuana indoors enriches the water with these very nutrients. It’s an amazing process which creates a hydroponic nutrient solution which feeds your plants exactly what they need.

If you want a nutrient solution to see you through every stage of growth you need an all purpose hydroponic nutrient solution which has secondary elements such as calcium, sulphur and magnesium and trace elements boron, copper, molybdenum, zinc, iron, and manganese.

When hydroponically growing marijuana you’ll see different stages of growth, all of which need different levels of nutrients. You can adjust the different nutrient levels needed as required to produce high quality plants and receive best results.

You’ll want to consider purchasing your nutrients for your plants. It’s cheaper to buy powder which mixes with water rather than the pre-mixed solution. Your selected solution will include Nitrogen, Phosphorus and Potassium which all play different roles. Nitrogen promotes healthy foliage, Phosphorus strengthens the roots and Potassium (K) encourages healthy growth.

When purchasing solutions the percentage not used up by Nitrogen, Phosphorus and Potassium is trace elements and inert material, this percentage will depend on the solution you choose.

Here’s what you need to know:

  • When the room you’re growing your plants in is below 80 degrees during vegetative growth you’ll need higher amounts of Nitrogen. 20-20-20,  23-19-17, 12-6-6 or something similar, with trace elements solutions should be just what you need to keep your plants healthy.
  • If the temperature is higher than 80 degrees you don’t need to worry about the point above.
  • When your plant is flowering you need more Phosphorus, the temperature does not contribute to this factor. Look for 15-30-15, 5-20-10, 2-4-3 or something similar, with trace elements.
  • It’s essential not to over fertilize your plant as this will kill it. If anything, it’s better to under fertilize them as they will just take longer to go rather than dieing. You’ll get instructions with your hydroponic solution packaging, but if you’re unsure less is more!
  • The plants absorb the evaporated water which will make your water reservoir drop, add 3 day old tap water to top it up.
  • You must discard the used solution and clean out reservoir, pump and equipment used to grow your plants with hot water every 2 weeks. Following this add 3 day old (or longer) water to the reservoir and then add fresh solution.
  • When you start a new crop you only need to clean the cups and tubing the plants are in.

Marijuana Nutrient Cycle

You should have a pump for the nutrient solution you decide to purchase. This pump should have a timer which should turn on every twenty minutes to submerge the roots of your plant. Once the roots are submerged the pump can shut down until it’s time to repeat. It’s important for the roots to get water within the 20 minutes and no longer otherwise they can become too long looking for their nutrients.

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The issue with your plants growing too long is that the nutrient solution won’t be able to make it to the top of your grow cups, which can lead to the root material ripping and result in the system being clogged. A clogged system will affect your plants negatively and reduce the efficiency of your system, if this happens you should take it apart and clean it.

It would be sensible to consider checking the root length of your plants every few weeks. The root should not touch the narrow point of entry for the solution into the cup holder.

If your roots are too long you won’t be able to remove the cups they’re growing in easily as they will be anchored to the internal channel, in this case you should trim them down with scissors. If you’d like to recycle your discarded solution, you can water your houseplants or outside plants to double their growth rate.


Why not Soil? 

When growing your plants you need ideal conditions, which is rare to find with soil. This is because there is a lack of organic matter left on the surface, contamination and biological imbalances. Plants feed on Nitrogen, Phosphorus and Potassium salts, which are broken down from organic matter by biological decomposition in soil.

Hydroponics can deliver high amounts of nutrients to enable your plants to survive, unlike soil which struggles to produce these levels of nutrients. Hydroponics allows you to know where you stand and allows you to feed to correct amount of food straight to the roots of your plant, this means the roots don’t need to search for their food.

You can easily measure and maintain the pH levels and nutritional value using hydroponics, ensuring your plants don’t go hungry. Unfortunately soil loses its nutritional value and pH and fertility are very difficult to measure.

Hydroponic systems can provided extended times of moisture, even constant exposure to moisture for your plants to stay healthy. If using soil plants are only exposed to moisture when watered.

Finally, hydroponic growing mediums are inert and steril, providing a happy, healthy environment for your plants. As we’re all aware, soil houses many pest, creatures and diseases which can be unavoidable.


Hydroponic Marijuana Setup

If you’re looking for a simple and easy to use system for growing your marijuana plants then you should consider the Ebb and Flow system. This is one of the most popular systems used and easy to get to grips with.

Hydroponic Marijuana Setup

How it works

  1. It has a reservoir containing nutrient solution located below a growing tray
  2. An inert, soil free medium like fiber or stone can be used to support plants grown hydroponically to anchor the roots. They’re designed to enable your to grow a healthy plant, enabling the roots to breathe by providing ideal retention of air and water.
  3. The growing tray the plants in their containers with a growing medium such as Rockwool.
  4. Ebb and Flow requires the growing bed to be filled with your choice of nutrient solution via a small pump on a time. This will feed and water your plants.
  5. The timer can shut the pump off and then the nutrient solution drains back into the reservoir.

The Ebb and Flow system are mainly popular due to their effectiveness, productivity, low maintenance and easy to use. They are perfect for any level of gardener, whether you’re just starting out or have years of experience the Ebb and Flow system will be perfect for your needs.


Other Systems you can Consider

There are various other systems for you to choose from. Following you can find a list and a brief description of other choices available to you.



This is a form of hydroponics where your plants will be suspended in the air, you will not need a growing medium for this.

It might be sensible to use a little amount to germinate the seed or root a cutting. Your plants will be kept in a chamber at 100% humidity level which is created by the roots being held in a water and light proof container.

To feed your plants using this method you’ll need a fine spray of nutrient solution.

By using this method you’ll allow the roots to absorb maximum oxygen which can increase the rate of growth by up tp 10 times than if using soil.

You won’t see much water loss using this method due to evaporation.

Continuous Flow 

This system is a ‘top feed system’. A 2” or 4” PVC tube is used with an even row of hole cut in for the plants to sit in a holder or pot. The plants are fed nutrients continuously down the PVC pipe over the root system.


Deep Water Culture

This method is recirculating direct water culture systems and can be know as bubbleponics. It’s been known to be similar to the earlier mentioned aeroponics system and is an effective, easy method to grow your plants.

The difference with this method is you submerge the roots into the nutrient system. You must add air by using an air rock such as used fish tanks otherwise your plants will die. By pumping significant amounts of air through the system, the bubbles created will maintain substantial oxygen to the roots. Using this method correctly will have a positive effect on the growth of your plants.

Drip Irrigation

This system can save on water and nutes, it’s also efficient on cutting down on waste. This method works by placing small droppers are placed next to the stem or roots of your marijuana plant within the medium. There will be small drops of the nutrient solution will drip out on a regular basis to feed the plants.

Nutrient Film Technique 

This method is very similar to the Ebb and Flow technique. This difference with this system is it’s more circular by the tray above the reservoir is tilted. The nutrients for your plants will be fed through the top and left to drain in a thin film which is located at the back of the tray and into the reservoir. This method allows the roots to feed and gives them access to air.


Wick System

To use this system it’s recommended for your marijuana plants to be sitting in pots with a soil medium. The thick wicks of cotton that connects the pots aggregate their roots with the reservoir underneath. The plants continuously suck up the nutrient solution when they’re dry through capillary action.

Sea of Green and Screen of Green

Both of these systems are more of a commercial route to take because yields and speed are essential, however it is possible to use them at home. They are a Dutch method rather than hydroponics. If you want to purchase a ready built grow room you’ll be saving yourself time, however by purchasing all the parts from the hardware store you’ll be saving money.

Marijuana Lighting

When growing Marijuana plants you may have the most success by using two different types of lights for different stages of growth, or simply at the same time. These lights are called high intensity discharge lights. Marijuana grows well from 420 to 730 nanometre, all of which using this method covers.

When choosing your light for vegetative growth you need to look for Metal halide light which is close to regular room light or compact fluorescent light which is more abundant in the blue or green spectrums.The flowering stage will benefit most from high pressure sodium which offers light in the orange, amber and red end of the spectrum.

We reviewed HPS – High Pressure Sodium Grow Lights and LED Grow Lights!

Although the lamps mentioned offer a lot of light, you can imagine how much energy is wasted through emitted heat. To manage the heat and avoid damaging your plants you’ll need a god ventilation system and a ballast to operate.The ballast regulates the current to the lamps and supplies sufficient voltage to start the lamps, this is essential in operating your lamps. The cost of this is around $250 for a 600W HPS/MH digital ballast, bulb and reflector combo.

Full spectrum LED lights are the commonly recommended lights to use. This is because they’re low cost, low power usage and the color spectrum they produce is perfect for growing marijuana plants. The advantages the full spectrum LED lights have over the high intensity discharge lights are:

  • They cover all stages of growth from seedling, vegetative and flowering
  • Run on approximately half of the electricity
  • Bulb life of around 50,000 to 60,000 hours
  • Emit very little heat
  • Do not require a ballast

As you can see lighting systems grow and change with the times, like everything. The full spectrum LED lights are a great step forward from the high intensity discharge lights, make your life a lot easier!

Marijuana Growing Seeds or Clones

You may know someone who grows marijuana plants, in this case you can ask them for some clones. You may have some friends who can save you some seeds out of any good marijuana they come across! If you don’t have access to clones then it’s a case of purchasing your own marijuana seeds.


Germinate the Marijuana Seeds

Before germinating your seeds you’ll need to get everything set up and tested to ensure it works unless you’re using clones, if this is the case you don’t need to germinate your seeds. You must choose your growing medium first before germinating your seeds. For instance, if you were to use rockwool cube you can start the seed on and surround it the growing medium of your choice. Remember that your seeds won’t be getting any nutrients from your growing medium, just support.

To germinate your seeds you must keep around 70% of the rockwool cube submerged in water when it’s at its maximum. It’s important to keep the top portion above the water so that the seed doesn’t submerge. Once your seeds have germinated at the roots have grown to around a quarter of an inch, you can place the seed so that it’s root down on your growing medium, in your hydroponic cups.


Vegetative Marijuana Growth

The vegetative phase is the first stage of growth. When considering your lighting options you must understand that if the position of your light is wrong it can cause your plant to either dry out and turn brown if the lights too close, or grow too tall to stretch to the light source if it’s too far away.

If you plan to use LED, metal halide or high pressure sodium from the very start then you must start with it being around 20 inches or more above the top of the plant (although this is less for LED). You should lower the light around an inch daily until you believe it’s in the right position and your plants are receiving the correct amount of lighting.

During this first stage of growth you should keep the light on for a minimum of 18 hours a day, even better if you can stretch to 24 hours a day to begin with. The longer you can keep the light on, the faster your plants will grow, but of course you’ve got to consider the cost of this.


Marijuana Flowering

When your plants meet the flowering stage they will begin to produce the most THC, CBN and CBD which are the active ingredients which produce a high when the female buds are smoked.

The minimum height for the plants to begin flowering is about 6 inches and the plant can have up to four sets of leaves. It will take your plant around 2 weeks to a month in the vegetative stage of growing in most hydroponic growing environments. To convince your marijuana plant that the days have got shorter and it’s time to flower you can change your light cycle to 12 hour on and 12 hours of complete darkness, your plant will then begin pre-flowering.

When flowering begins you can cut the light exposure down to 12 hours a day, great news for your electricity bill! If the flowering begins when the plant is very small then it will continue to grow taller for two to four weeks from the beginning of this stage.

Once the plant has reached its maximum height all of its energy will go into flower production. However if you begin the flowering stage when your plant is more mature and has grown taller rather than beginning at the minimum height then you can expect the flower production to happen in about ten days.

It can be extremely difficult to limit the height of marijuana plants. One of the easiest methods is to raise the height of your chosen light source as the plant grows, you must keep a close eye on the growth if using this technique. Other methods of limiting the height can be very complicated and difficult.

If you’re planning to use one of the more complicated techniques then the ‘Marijuana Grower’s Guide’ is just what you need to get you well equipped! This guide has the most comprehensive descriptions for limiting the height of marijuana.

During the flowering stage it’s extremely important that the dark stage is in fact, dark. There must be no room light, sun light or any other source of light reaching your plant during the 12 hours of darkness your plant should be receiving every day. The best thing to do is leave your plant alone during this time and don’t be tempted to go and check on it so that you avoid any chance of light reaching it.

The strongest light that should reach your plant during the flowering stage is a light equal to moonlight. If a light source any stronger reaches your plant you risk delaying the flowering stage, you may even be at risk of the plant not flowering if light exposure continues and your plant will be stuck in the vegetative stage.

The flowering stage is easy to spot, just look out for what looks like little white hairs developing at the bud sites. This should become visible after about ten to fourteen days of the flowering light cycle, so keep your eyes peeled! When you can visualize this stage then it’s time to remove the mail plants (this isn’t required if you have female clones).

The red or white hairs that you see are pistils, they will turn into big buds if your plants are growing healthily.

Here are seven tips on how to determine the sex of your plants:

  1. Female plants tend to have more complex branching as they grow, whereas males tend to be slightly taller and less filled.
  2. Male plants will reach maturity and grow taller around two weeks before female plants.
  3. Male plants pollen sacs, they grow taller so that they can drop the pollen on to the females reproductive organs.
  4. The pollen sacs the males possess will eventually open up to be yellow flowers. Females have hair whiteish pistils which will be sticky so that it can catch the pollen dropped from the flowers.
  5. The best way to determine the sex before the plant reaches maturity is to take a cutting from a number of plants and place it in soil to grow for a few days. Force flowering by using the 12 hour on 12 hour off light cycle and you’ll be able to determine the sex, this is called cloning. You must keep track of which clone came from which plant as they’ll be the same sex as their host.
  6. If the plant sprouts from the top or bottom of the seed it’s generally a female. If the plant is sprouting from the side they’re generally male. This method of determining the sex of the plant has a 90% success rate and may not be reliable used by itself.
  7. Hermaphrodites occasionally occur and can make it very difficult to determine whether the plant is male or female. Hermaphrodites are plants which exhibit both male and female reproductive capacities. They can be the result of environmental stress and can send mixed signals. If you start to notice flowers and pistils on the same plant, try pruning off the flowers to ensure that the marijuana plant doesn’t self-pollinate (or pollinate other surrounding females).

The flowering cycle generally lasts around two months, but depending on the type of seed it can take a little longer. It should take around three to four months in totally to grow a crop in a hydroponic environment, it’ll take much less time if you’re using the sea of green or screen of green methods.

Important facts to remember for the flowering stage are:

  1. Less than 12 hours light will reduce flowering speed and overall yield.
  2. Putting the lights on during the 12 hour dark period even if it’s a short period will harm your plant and leave them stuck in the vegetative stage.
  3. If you want to work in your grow room whilst it’s dark then you can use a green light bulb, green light doesn’t effect the plants.
  4. You can leave your plants in 36 hours of darkness to send the message that it’s time to flower. This can decrease the time in which flowering begins.

Harvesting, Curing and Storing Marijuana with no Smell!

This stage is crucial to producing high quality marijuana. There are 3 key steps you need to take to produce the perfect buds.


1. Timing your harvest

Timing is everything! If you harvest too early then you will miss out on the active ingredients THc and CBD, along with other good stuff to give you best results. If you wait too long to harvest then you’ll risk these same molecules to begin to degrade.


How can you tell it is Ready?

When choosing the perfect timing to harvest you’ll begin to see many signs that your plant is ready. The signs that your marijuana is beginning to reach maturity are:

  • They will merge together in heavy kolas
  • Each ovary will swell
  • Tiny crystals will be visible around the flower
  • Flowers become sticky to touch
  • Aroma may become pungent
  • As the flowers swell the white pistils begin to darken, turning to a reddish brown color

You may notice that the larger fan leaves are beginning to turn yellow and wilt, there’s no need to worry your plants aren’t ruined! You can in fact remove these leaves to allow more light to the lower parts of the plant.

The list above notes the signs that harvesting is approaching, however many people go by the color of the trichomes. This is the tiny structure on the flowers and trim leaves that produce resin and is where THC resides! To inspect these you’ll need some form of magnifier. There are three changes that the trichomes go through as they mature that you’ll be able to observe:

  • They swell and their heads flatten (also known as ‘mushroom’)
  • Turn from being clear to milky or clouded
  • Turn amber or brown

The changes in trichome color can provide a good guide to the levels of THC and CBD in each bud and determine whether your plant is ready to be harvested.

For many, harvesting when trichome is clear is too early, although you’ll still get high the effects may be light because it hasn’t had as long for the active ingredients and molecules to peak.

When the trichomes are milky you’ll get a good hit without it being too heavy. Finally once the trichomes begin to turn amber, depending on when you choose to harvest they effect will become heavier and heavier the more the trichomes change color.


Flushing your Plants

Marijuana plants can suffer from a build-up of salts or nutrient residues which is why it’s essential to flush your plants. A common method is using plain water every 10 days throughout the grow to help clear out this build-up.

If you plan to flush your plants 3 – 7 days before harvest this will improve the quality of your buds. To do this with your hydroponic system you should run clean water through the system for the last few days, pH your water to about 5.8, although pH is not as critical at this stage as there are no nutrients to lock out. Don’t worry if you experience some leaf yellowing, it’s perfectly normal!


Chopping your Plants

If you have the time and patience to cut your plant in sections, this will give you the best results! The smaller leaves protect the trichomes and would be best to leave on throughout the cutting and drying stages.

To cut your plants effectively remove the fan leaves first and handle the branches extremely carefully, otherwise the trichomes could fall off. Using a sharp pair of secateurs or fiskars cut each branch from the plant.

2. Drying your buds properly

How to Dry your Buds

To preserve the terpenes in your buds it’s essential to dry slowly, this will preserve the flavor, weight and smell. You should prevent mold and fungus growing and ruining your bud by ensuring there is good air circulation where you’re drying your buds.

You should have a drying area prepped and ready for your freshly harvested branches. It should be a dark area with clean fresh air and ventilation, with enough room for your branches to have plenty of space surrounding them.

Ensure you hang your branches with plenty of space between one another. You can purchase custom made drying cabinets or boxes to provide the perfect environment to dry your buds. It is possible to purchase commercial drying boxes or simply make your own if you’re a dab hand at DIY.

When drying your buds you should turn them around so that the air flow meet all of the buds. Be sure to inspect your plants regularly, drying can take from a few days to a couple of weeks. The branches and stems will begin to crack rather than bend between your fingers when your plants are dry.

3. Curing your buds properly


Before the final cure you must trim your freshly grown marijuana, you can use a clean sharp pair of scissors to do this. Gently remove any remaining leaves that could be shielding the buds.



To cure your marijuana you need to separate the individual buds from the stems and place them in a glass jar. Open the buds up twice a day to allow them to breathe for fifteen minutes for the first week or two that they’re in the jar. By doing this it allows a complete air exchange and removes any remaining moisture.

You’ve now completed the finishing touch to your marijuana and we’re sure it’s going to make all the difference to the quality of your smoke! Well done for having the patience to follow every step through!



We hope this hydroponic marijuana grow guide has given you all the information you need to grow high quality plants. Remember to read through the guide before you start to ensure you have all the equipment you need to get the best results! Happy growing!

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