How to Grow Hydroponic Marijuana What is Marijuana Hydroponics and How to Grow Weed with Hydroponics? In Latin, the word hydroponics means literally “water working.” Growing marijuana The Flora Series from General Hydroponics is your tried & true nutrient solution for hydroponic cannabis growing, trusted since the 1970s Learn how to best use hydroponic growing systems and techniques to cultivate cannabis and how these techniques can improve your crop.
How to Grow Hydroponic Marijuana
What is Marijuana Hydroponics and How to Grow Weed with Hydroponics?
In Latin, the word hydroponics means literally “water working.” Growing marijuana with hydroponics is the practice of growing plants in either a bath or flow of highly oxygenated, nutrient enriched water. Growing marijuana hydroponically simply means that you grow the plants in an inert, sterile growing medium instead of in soil. All of the plants’ nutrient requirements are supplied when you mix water with the nutrient solution. Hydroponics introduces the water, nutrients and air to the roots through the growing mediums and since using hydroponics bypasses the web of roots and the energy required for the plant to acquire the nutrients you get faster growing plants.
Plants are 80% to 95% water; the remaining parts are carbon, oxygen and hydrogen. Plants extract these elements from the air and water so nutrients are actually a very small amount of the total weight of a plant. It is the plants entire atmosphere that needs to be controlled within the hydroponic environment to produce perfect crops. Additionally, very little water is lost to evaporation in a hydroponic system, owing to its application in drought stricken areas.
Marijuana plants, and in fact all plants, do not need to be in a living soil, they require nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S). Those are the macroelements (the big ones) and the small elements known as microelements are iron (Fe), chlorine (Cl), manganese (Mn), boron (B), zinc (Zn), copper (Cu) and molybdenum (Mo). Growing marijuana indoors with hydroponics, water is enriched with these very same nutrient salts, creating a hydroponic nutrient solution which is perfectly balanced. An all purpose hydroponic nutrient solution with secondary elements like calcium, sulphur and magnesium and trace elements boron, copper, molybdenum, zinc, iron, and manganese will get you through all stages of growth. But depending on the stage of growth, you can adjust different nutrient levels needed at different times to optimize your yield. A 15-15-15 solution contains 15% Nitrogen; 15% Phosphorus; 15% Potassium. A 20-10-5 solution contains 20% Nitrogen; 10% Phosphorus; 5% Potassium. The percentage of the solution not used by N-P-K is trace elements and inert material. If you are buying hydroponic nutrients, get the powder kind that mixes with water. It is much cheaper over the long run when compared to pre-mixed solutions.
N = Nitrogen P = Phosphorus K = Potassium
- Higher amounts of N are needed when the temperature will be below 80 degrees in the grow room during vegetative growth. 20-20-20, or 23-19-17, or 12-6-6, or something similar, with trace elements should do it.
- If temperatures are higher than 80 degrees in the grow room, you need not worry about more N in the formula during vegetative growth.
- During flowering the plant needs lots of P, regardless of temperature. 15-30-15, or 5-20-10, or 2-4-3, or something similar, with trace elements should do it.
- Do not over fertilize your plants as too much fertilizer will kill your plants. If you under fertilize, plants will take longer to grow but will not die. Follow the mixing instructions on your hydroponic solution package, if you aren’t sure, use less rather than more.
- As water evaporates it is absorbed by the plants, your water reservoir level will drop. Add tap water that has been aged 3 days or longer to the reservoir. I don’t add nutrient solution when I top up the tank, some people do.
- Change the nutrient solution every 2 weeks. That is, discard the old solution and clean out the reservoir, pumps, and other equipment that is used with HOT WATER. After cleaning, add tap water that has been aged 3 days or longer to the reservoir then add nutrient solution. You only need to clean the cups and tubing the plants are in before you start a new crop. More detail on nutrients.
Marijuana nutrient cycle
The timer that starts to pump the nutrient solution should turn on and the solution should submerge the plants roots about every twenty minutes. As soon as the roots are submerged, the pump can shut down. If it takes longer than 20 minutes for the roots to get water, the roots will usually grow long, and they can grow very long looking for the nutrient solution source. In fact they can grow so long and thick that they prevent the solution from reaching all the way up your grow cups. This will also raise the chance of root material being ripped out and clogging the system. Once the flow is clogged by root or other material inside, you will have to take the garden apart and clean it. Check the root length every few weeks. If it is hard to remove the cups the plants are in because the roots are anchored to the internal channel, the roots are too long. The root should be short enough to not touch the narrow point where the solution enters the cup holder. If they are too long, trim them down with scissors. Make sure they are not going too far, but don’t cut unnecessarily. The old solution that you are discarding can be used to water house or garden plants. This will at least double the growth rate if you usually water your plants with regular tap water! More detail on nutrients.
Why not soil?
In soil, biological decomposition breaks down organic matter into the basic nutrient nitrogen, phosphorus and potassium salts that plants feed on. Water dissolves these salts and allows uptake by the roots. For a plant to receive a well balanced diet, everything in the soil must be in perfect balance. Rarely, if ever, can you find such ideal conditions in soil due to the lack of organic matter left behind on the surface, contamination and biological imbalances. Soil is not able to produce a high volume of nutrients as hydroponics can deliver. Hydroponics takes the desired amount of food directly to the root rather than making plant’s roots look for it. Soil loses its nutritional value and is difficult to measure in terms of pH and fertility. With hydroponics the pH and nutritional value of the water are easily measured and maintained, so plants always have enough to eat. Only when you water your soil plants, the basic elements can dissolve into the water. In a hydroponic system, moisture is present for extended periods of time or for all the time. In addition, soil plays host to many nasty little creatures, pests and diseases while hydroponic growing mediums are inert and sterile making a very hygienic environment for the plant and owner.
Hydroponic marijuana set ups
All growing described on this page is done using the Ebb and Flow system. The Ebb and Flow system is one of, if not the most popular hydroponic methods for growing weed. It is simple and easy to use. It works like this: A reservoir containing nutrient solution is located below a growing tray. To support the plants in a hydroponic system, an inert soil-free medium like fiber or stone, may be used to anchor the roots. These hydroponic mediums are designed to be very porous for excellent retention of air and water that’s necessary for a healthy plant – roots need to breathe too. The tray contains the plants in containers with a growing medium like Rockwool, lava rocks or the like. A basic system known as ‘Ebb and Flow’ requires the the growing bed to be filled with a nutrient solution by a small pump on a timer to feed and water the plants, the nutrient solution ‘flows’ in. The timer then shuts the pump off and the nutrient solution drains or ‘ebbs’ freely back into the reservoir. Ebb and Flow systems’ are favored because of their low maintenance, high productivity, and ease of use. Ideal not only for the beginner, but for the advanced gardener as well.
There are lots of other systems to consider:
Aeroponics – This method of hydroponics goes without a growing medium, although a small amount may be used to germinate the seed or root a cutting. Plant roots are suspended mid-air inside a chamber kept at a 100% humidity level and fed with a fine spray of nutrient solution. This mid-air feeding allows the roots to absorb much needed oxygen, thereby increasing metabolism and rate of growth reportedly up to 10 times of that in soil and there is nearly no water loss due to evaporation. The mist is created by special nozzles to the root system on a regular basis. The roots are held inside a water proof and light proof container which helps create a high humidity area. Continuous flow / Top feed system – This is the system you often see pictures of. Using a 2″ or 4″ PVC tube with holes cut into the top at regular intervals for the plants to sit in a holder or pot. The nutrients are continuously fed down the PVC pipe over the root system. Deep Water Culture (DWC) + Recirculating direct water culture systems (also known as RDWC) + BubblePonics – This is a simple yet effective way to grow, it is similar to the mist Aeroponics system in some ways. However the concept is to submerge the plants roots in the nutrient system, now without air they would die, so you add an air rock like used fish tanks. If you pump significant air through the system the bubbles maintain oxygen to the roots and they grow really well. Drip Irrigation – A great way to save water and nutes. Used throughout large outdoor farming systems to cut down on waste, small droppers are placed right next to the stem or roots of the marijuana in their pots within the medium. Small drops of the nutrient system will drip out regularly to feed the plant. Very low evaporation and good for stealth grows too because it is silent. Ebb and Flow – As discussed above the nutrient solution floods a tray situated above the reservoir and then ebbs back into the reservoir in the process feeding the plants with their roots situated to the tray. Nutrient Film Technique (NFT) – Similar to the Ebb and Flow technique but it is more circular. The tray above the reservoir is tilted and the nutrients fed in from the top and let to drain in a thin film down the tray back into the reservoir, it lets roots feed and have access to air. Wick system – An easy system where by your marijuana is usually situated in pots, which can have a soil medium, there are thick ‘wicks’ usually of cotton that connect the pots aggregate with their roots with the reservoir below. The nutrients solution is constantly sucked up by the plants when they are dry through capillary action. Sea of Green (SoG) – This is Dutch method for growing rather than a hydroponic method. Read all Sea of Green here. Screen of Green (Screen of Green) – Very similar tot he Sea of Green system but involves a screen situated above the marijuana heads, read more above Sea of Green. Sea of Green (SOG) and Screen of Green SCOG – These growing systems are used more by commercial operations where speed and yields are paramount but can be used in smaller home grows. The equipment is different and you need cannabis strains that are capable of flowering after a short vegetation period, read more. If you would rather buy a ready built grow room rather than grab all the gear from the hardware store (they will know what you are making), it may cost a little more but all parts will be included and you will save time by getting everything at once. More about hydroponic grow systems.
Since modern hydroponics began people have used high intensity discharge (HID) lights including Metal Halide (MH) or High Pressure Sodium (HPS) to grow marijuana and more recently with great success, LED grow lights. Metal halide light is close to regular room light or compact fluorescent light CFL and is more abundant in the blue and green spectrum’s which is best for vegetative growth. While high pressure sodium HPS offer light in the orange, amber and red end of the spectrum which is best for flowering stage (later) growth. Growers often use these two lights in tandem, MH for vegging and HPS for flowering or both at the same time. Marijuana grows well from 420 through 730 nanometres which can be covered in this method. HID lamps like the MH and HPS offer a lot of light but just as much wasted energy is emitted as heat. You will need to manage that heat with a good ventilation system. HIDs also require a ballast to operate so make sure you buy one of them. Expect to pay about $250 for a 600W HPS/MH digital ballast, bulb and reflector combo. Full spectrum LED grow lights are what the pros have turned too now, we know some of the large greenhouses (think big name seed companies) in the Netherlands have turned too as they offer far more control, lower electricity costs while heat and space issues are decreased. Why are LEDs now a good option? The cost of LEDs, their power and the color they produce (spectrum) is tuned perfectly for marijuana growing. LED grow lights, in particular full spectrum LED grow lights, number of advantages over HIDs such as covering the full grow spectrum from seedling, vegetative and flowering stages, run on approximately half the electricity and have bulb lives of around 50,000 to 60,000 hours! A 1000W HPS is the equivalent to approximately 500W LED (true draw). Good LEDs run cool, have no fans or excellent silent fans and emit very little heat – and do not require a ballast. LED grow lights are a great solution to the old HIDs. Much more on grow lighting.
Marijuana Lighting Guide
Marijuana growing seeds or clones
If you know someone who grows, ask them for a few clones. If you don’t have access to clones you will have to buy marijuana seeds. If you don’t already have some, you can ask you friends to save you seeds out of any good weed they may come across. If you need seeds we totally recommend reading this cannabis seeds guide.
Hydroponics: The original way to grow perfect cannabis every time
There’s a reason hydroponics is such a classic choice for cannabis: It’s easy to set up, it’s space efficient, and without the variability that comes with soil, you can fine-tune your plants’ nutrients for every part of the growth cycle. There’s almost zero guesswork involved, too, thanks to decades of growers that came before you—as long as you’re able to measure things—so it works for beginners and old hands alike.
When hydroponic herb rose to prominence in the 1970s, General Hydroponics, now part of Hawthorne Gardening Company, was right there on the ground floor. By 1976, they’d released their three-part Flora Series, the OG cannabis nutrient system that growers still swear by today.
Using General Hydroponics’ personalized assistance, clear guides, and straightforward nutrient system, first-time growers can get all the basics for starting their first crop—but once you have the basics down, it’s just as easy to personalize and adapt to every individual grow.
Whether you’re just starting out with cannabis cultivation or you’re used to growing using soil, hydroculture is the most foolproof way to get a full, healthy harvest. Here’s what you need to know.
What is hydroponics?
The simple version: Hydroponics is a way of growing plants with a blend of water and nutrients instead of soil. While humans have been growing plants without soil for eons, technology has developed in the last century. It was used to feed troops in World War II, and later, it would be used to grow lettuce in space.
Hydroponics gradually spread from scientists to gardeners and hobbyists. While a lot of them were just growing veggies, it especially caught on with cannabis growers. Cannabis is a unique plant with very specific lighting, humidity, and nutritional needs, and hydroponics gave them a level of control they’d never had before. It made it easier than ever to avoid pesticides, too, since many common pests require soil to thrive.
Getting started with a hydroponic cannabis crop
A cannabis plant has two basic stages, although they break down into smaller ones. During the grow period, the priority is developing leaves and stems, creating a sturdy, healthy plant. With that strong foundation in place, you move onto the bloom phase, creating as many sticky buds as you can. For maximum yields, both of those processes need different nutrients—for example, cannabis needs the most nitrogen at the end of the growing period—and with hydroponics, it’s incredibly easy to adjust them to the plant’s exact needs at any given time.
To get started, you can either buy a premade hydroponics system or, if you’re thrifty and handy, build your own. Make sure your plants are getting adequate light, either naturally or from grow lights, and plenty of ventilation. (If you stick with it, you’ll want to look into getting more precise environmental controls, like an air conditioner.) Check your water for the proper pH level before mixing in your nutrients.
General Hydroponics’ Flora Series is the simplest way to make sure your plants are well-fed. Your plant gets all the nutrients you need in just three different blends—FloraGro®, FloraBloom®, and FloraMicro®—mixed in different combinations depending on the plant’s growth stage.
General Hydroponics’ straightforward feedchart, built from decades of experience, gives both a simplified, four-step nutrient plan and a week-by-week breakdown, giving your crop the right balance for a productive harvest.
The team at General Hydroponics are the original experts on hydroponic cannabis—and they’ve prepared a whole knowledge library to get you started. Articles for beginners cover the basics and frequently asked questions. Next-level growing resources give you everything you need to know about your growing environment, keeping your plants healthy, and troubleshooting.
But if all that doesn’t cover it, you can always give them a call. They’ll get a hydroponics wizard on the line to make sure you’re set up for success.
How to Grow Hydroponic Cannabis
I n the previous post, we gave an overview of hydroponic gardening including its origins, the various systems and techniques, and medium options for a hydroponic grow. In this next article, we will focus how to use hydroponic systems specifically for growing cannabis.
What Is Hydroponic Cannabis?
The common nickname for cannabis—“weed” —comes from its ability to grow almost anywhere, under varying conditions and different climates. “Hydroponic cannabis” simply refers to plants grown using a nutrient-water solution and an inert growing medium rather than nutrient-rich soil. This method could be something as basic as hand-watering pots of inert medium with a nutrient solution. As discussed in the first part of this series, sophisticated systems with multiple pumps, timers, and reservoirs can take some of the daily labor out of growing, but they require more maintenance and setup time as well as a greater initial investment.
Cannabis growers have been using different hydroponic methods for many years as a way to maximize yields and speed up growth, the two main advantages of soilless growing. Working with soils indoors can be inefficient and difficult for a number of reasons:
- You may not be able to recycle soil
- Susceptibility to pest problems
- Difficult to determine proper amount of nutrients
- Need to carefully monitor soil pH
- Soil quality significantly influences the final product
With some hydroponic methods, you get to use small amounts of grow media that can often be reused while also precisely controlling what nutrients the plants are receiving and pH levels. With such levels of control, growers find that their buds are bigger, healthier and more potent.
Whether you have grown cannabis before or have no experience growing cannabis whatsoever, hydroponics can be a great way to produce cannabis in any size space. At first it can be confusing and slightly overwhelming, but by learning the basics you will come to understand it’s not as difficult as you imagined.
Set Up Your Hydroponic Cannabis Growing System
There are numerous setups for growing hydroponically with varying benefits that were discussed previously here. And while there are several types of hydroponic setups that don’t use any type of growing medium at all, many of them still use some sort of substrate to support root growth.
Various materials all provide slightly different benefits and drawbacks, so some thought should be put into choosing the right medium for your cannabis plants. In this article, we are going to be utilizing the drip line hydroponics technique.
While this system is built from the ground up, it should be noted that there are plenty of plug and play systems available for those looking for something that is easy to set up. Plug and play systems come with everything you need in a streamlined package to allow growers to get started on the right foot.
First we will start with the supplies needed. Keep in mind this is just an example, and depending on your space and desired results, many things can be tweaked in a hydroponic system to make it most beneficial to you. This list specifically outlines equipment needed to install your hydroponic system and does not include lights, fans, filters, and other basic needs for any grow room.
Hydroponic Cannabis Supplies:
- 3 or 5 gallon bucket (one for each plant)
- Grow table
- Clay pellets (enough to fill each bucket)
- Rockwool cubes (one 1.5-inch starter plug per plant)
- Reservoir tank (depending on the size of garden)
- Water pump (the bigger the better)
- Air pump
- Air stone
- Plastic tubing
- Drip line
- Drip line emitters (one or two per plant)
Browse Hydroponic Growing Supplies
Once you have gathered your materials you can begin to construct your hydroponic setup.
- First, set up your reservoir. Your reservoir is where your nutrient solution is held. A reservoir can come in all shapes and sizes depending on your grow space and size, and it holds the water pump and the air stone. It will have a line in from the air pump to the air stone and a drainage line in from the grow table. The reservoir will have a line out from the water pump to the drip line and the power cord for the water pump.
- Next you will create your grow table. The purpose of the table is to contain and return the excess water from the plants to the reservoir. To do this successfully, the table needs to have a low point where all the excess water will travel to. This low point is where you install the drain that will take the water back to the reservoir via plastic tubing.
- You can then add your 5 gallon buckets filled with clay pellets on the table. Before using clay pellets, you should soak the pellets overnight to allow them to become fully saturated with water for your plants to drink. Also, the buckets need to have holes drilled in the bottom to allow them to drain excess water onto the grow table. It is important that the holes are about half the diameter of the clay pellets to prevent the pellets from passing through or clogging the holes.
- Take the plastic tubing coming off of the water pump and run the line to the grow table. From here you can use drip line equipment to puncture holes in the plastic tubing and extend drip line to each bucket. Finally, attach drip line emitters to the end of the drip lines.
- From here you can run your system without plants to see if everything is functioning properly. The system should not have standing water anywhere. The air pump should always be running to keep the water in the reservoir oxygenated and moving, while the 5 gallon buckets and grow table drains any excess water back into the reservoir.
- At this point you are setup and ready to create your nutrient water solution in your reservoir. Below we will introduce information about nutrients and how to use them to grow your cannabis plants.
- Once your solution is ready, can introduce your plants. Take the starts or clones that have begun growing in rockwool and place them into the clay pellets. Insert the drip line so that moisture is reaching the rockwool and roots of your starts.
A benefit this setup offers is that it can easily be expanded as you want to grow more plants as long as your reservoir has enough capacity to provide all the plants with enough water. To expand a drip line setup, all you need to do is add additional lines to the new pots.
Nutrients for Hydroponic Cannabis
When growing hydroponically, you are responsible for providing all of the nutrients necessary for plants to survive. Nitrogen (N), Phosphorus (P), and Potassium (K) are the three essential nutrients for plant growth known as macronutrients. Additionally, there are secondary and micronutrients that will help the plant develop as well. These include Boron, Calcium, Copper, Iron, Magnesium, Sulfur, and Zinc.
Many companies sell hydroponic nutrient solutions that are specifically designed for certain stages of growth. Nitrogen-rich nutrient solutions will be used in the vegetative stage while phosphorus-rich nutrients become more necessary in the flowering phase.
Nutrients will come either pre-mixed in a solution or in powder form. While powder form might be cheaper and less bulky, it is best to stick with liquid pre-mixed nutrients if you are a small-time grower as they mix with water easily and are more forgiving.
Explore Nutrients for Your Hydroponic Cannabis
When mixing in nutrients, take a few measurements to make sure your solution is safe for the plants. First, make sure you have the right EC (electrical conductivity) reading, and secondly, ensure your pH reading is correct.
The EC reading is how growers can tell how strong their solution is, and how mineral-rich the water is. The more minerals, the higher the EC rating will be. Generally speaking, a reading between 0.8 to 2.0 is appropriate for growing cannabis. When a plant is young, it will need a lower amount of nutrients as opposed to when it is flowering and growing quite big.
Another common measurement used is ppm (parts per million) which is another way of looking at how nutrient-dense your solution is. There are two different scales for ppm used in the cannabis industry: the 500 and the 700 scale. The most efficient way to determine ppm is to take an EC reading, multiply it by either 500 or 700 depending on the scale you are using. An EC reading of 2.0 would equal either 1,000 ppm (500 scale) or 1,400 ppm (700 scale). Many readers used to measure EC or ppm will do this conversion for you.
The lower the ppm, the less nutrient-dense a solution is. As a general rule, aim for the following densities based on your plant’s age:
- Seedlings/early sprouts – 100 to 250 ppm
- Early vegetative stage – 300 to 400 ppm
- Full vegetative stage – 450 to 700 ppm
- Early blooming stage – 750 to 950 ppm
- Full mature bloom/ripening stage – 1,000 to 1,600 ppm
Note what scale the nutrients you are using are based upon before making any nutrient solutions.
Next, you’ll need to balance the pH level. Between 5.5 and 6 is ideal for cannabis to absorb the nutrients. If levels are off significantly, the plants will fail to uptake the nutrients and will suffer deficiencies.
You should continue to monitor your solution by taking readings two times a day to make sure everything is at the correct levels. Regardless, it is good practice to switch out your solutions every week or two to keep the solution as optimal as possible.
Caring for Cannabis Grown With Hydroponics vs. Soil
Raising a plant with hydroponics is different in many ways from growing in a soil garden. One thing to consider is the support the plant is receiving. Unlike a plant growing in soil, plants in hydro mediums might be vulnerable to tipping or breaking. Trellising your garden will help to prevent this from happening and will also allow you to train your plants to grow in specific directions.
Another thing to consider is pruning. With hydroponics, your plants can grow extremely fast. This means you need to be diligent about pruning. Removing all the bottom foliage and topping your plant before switching to its flowering cycle will allow your top colas (the large, topmost buds) to receive all the energy they need.
Growing hydroponically does require that you invest a good amount of time and money into developing your system prior to actually starting your garden. Additionally, you’ll want to make sure your system works effectively and your nutrients are high quality so that your plants will flourish. Once you gain a knack for hydroponics, you’ll be on your way to producing world-class cannabis that is well worth the effort.
Have you ever tried hydroponic growing techniques before, either for cannabis plants or other grows? Share your advice, tips, and questions in the comments section below!