The Flora Series from General Hydroponics is your tried & true nutrient solution for hydroponic cannabis growing, trusted since the 1970s 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 How to Grow Hydroponic Cannabis at Home Hydroponics is when you grow your cannabis plant in an inert medium like coco or a reservoir of water, and provide all the nutrients to the plant directly
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 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.
How to Grow Hydroponic Cannabis at Home
Hydroponics is when you grow your cannabis plant in an inert medium like coco or a reservoir of water, and provide all the nutrients to the plant directly in the water.
Growing in coco coir can be considered a type of hydroponics since it naturally contains no nutrients and you must provide all the nutrients in the water. However, when you say “hydroponics” most people think of this:
When it comes to hydroponic cannabis…
Differences Between Soil & Hydro
- The optimum pH for coco and hydroponics is 5.5-6.5, while the optimum pH for soil is 6-7
- Nutrients must be provided from when a hydroponic plant is a seedling (in seedling doses to start), otherwise the seedling will grow slower because it only has what’s contained in the seed itself. In soil you don’t need to add nutrients for a few weeks since there’s already some in the soil
- Growing in coco coir (a growing medium that looks somewhat like soil but is actually made of dried coconut husks) gives you results that are somewhat between growing in soil and growing in a hydroponic reservoir of water – you get a lot of the benefits of both
Pros of Hydro
- Plants in hydroponic setups generally grow faster in the vegetative stage than soil-grown plants
- Less likely to get bugs
- Buds can feel more potent
- If growing in a reservoir you don’t have to worry about watering your plants when they’re dry, over/under watering, or removing runoff. Everyone is different but I find maintaining a hydro reservoir easier than moving the plants around or watering and using a wet vacuum to remove runoff (but we all have our personal preferences!)
- If growing in a reservoir you use a very efficient amount of nutrients since you only mix up new water a few times a month, and only toss old water after the plant has already used up a lot of nutrients, which can save quite a bit if you’re using expensive nutrients and is better for the environment (compared to drain-to-waste)
- You have more control over nutrient levels, PPM, and pH – for the mad scientists among us who want to get the most out of our plants as possible!
Cons of Hydro
- Hydro usually takes more preparation/setup than growing in soil. You’re providing more for the plant instead of letting the soil do some of the work for you
- It can be easy to get root rot in hydro if you don’t provide your plant with a good-bacteria supplement like Hydroguard.
- Soil-grown buds may have a more complex or stronger smell than hydro-grown buds, especially if grown in composted living soil without any liquid nutrients
- Growing in soil is more intuitive for many people, and some people already have experience with soil from other types of gardening!
Is Hydroponics Good for Growing Cannabis?
Have you seen cannabis plants growing with their roots just floating in a reservoir of water? This type of hydroponics is known as Deep Water Culture (DWC), and has been around for over a 100 years! As more growers gain experience with this medium, DWC has become increasingly popular for growing cannabis. Hydroponic setups are really neat and offer some big benefits over growing in soil!
Benefits of Hydro Over Soil
- Plants grown in a hydroponic reservoir tend to grow faster in the vegetative stage, resulting in bigger yields and faster harvests
- Hydroponic buds tend to be more potent and often cost more at dispensaries
- Once a hydroponic reservoir is set up, it does not take a lot of work or time to maintain. Instead of regularly watering plants and removing runoff, a hydro reservoir only requires you dip a PH Pen and top off with more water or adjust as needed.
Cons of Hydro
- Takes more time and effort to set up than soil or coco
- Buds grown in soil without added nutrients tend to have a stronger smell than buds grown with liquid nutrients like in a hydroponic setup (though if you’re trying to keep things low odor this might be a benefit).
- Unless you protect your roots by using the right supplements and equipment, your plants may struggle with root rot. Luckily if you follow the steps in this tutorial you don’t need to worry about root rot killing your plants!
Hydro is a no-brainer for me. Whenever I go back to a hand-watered grow like coco coir, I am always surprised by how much extra time it takes to water plants and remove the runoff. The most intimidating part of hydro is just getting started – after that it’s actually really easy to take care of your plants. In my opinion, hydro is far easier and less time consuming than growing in soil or coco coir once you’re set up. If you are interested in hydro, go for it! If you follow this tutorial you will succeed!
Today I’ll teach you how to set up your hydroponic reservoir for growing cannabis, and I’ll show you what you need to do each day for optimum growth
How to Grow Cannabis in DWC
So there are five major parts to getting set up. You need….
- Grow Environment – I personally recommend a grow tent as opposed to building your own environment from scratch.
- Grow Light – If you don’t already have a grow light, I recommend getting a 250W, 400W or 600W HPS grow light for your first grow. They are the most consistent type of grow light and get really great results in DWC.
- Nutrients – I highly recommend getting GH Flora trio, Calimagic (Cal-Mag supplement) and Hydroguard.
- Seeds – Learn where to get seeds
- DWC tank – Learn how to build your own (it’s surprisingly hard to find a pre-made tank considering how cheap all the parts are!)
Once you’ve got your gear and supplies, it’s time to get set up and start growing! Here’s a quick overview.