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The Ultimate Guide to Growing Marijuana Using Hydroponics

Jan 22, 2021
Hydroponic Growing

Introduction to Hydroponics Marijuana 

Are you interested in learning how to grow weed seeds for your own use? Perhaps you have been growing weed for a while now for personal consumption and you want to start selling to others? Maybe you have wanted to take the plunge and join the ever-growing ranks of pot growers, but don’t have land outside, or even space for pots outside, to grow your crop? For you, growing marijuana using hydroponics may be the solution that you have been looking for.


Guide to Getting Started


In this ultimate guide we are going to cover “all the bases” by giving you the big picture of this exciting method of growing pot. But there is really more we could say that can be detailed in a single web page, so we invite you to follow up by checking out a more detailed discussion at


What is Hydroponic Growing?




According to Wikipedia, hydroponics is “… a method of growing plants, usually crops, without soil, by using mineral nutrient solutions in an aqueous solvent.”


Breaking down this definition helps us to get an overall understanding of what hydroponics is: a way to grow plants without soil, by submerging the plants in a liquid that contains nutrients suspended in it.


In traditional, soil-based growing, the plant’s root system is supported in soil, and the plant draws both its needed nutrients as well as water directly from that soil.


In a hydroponic growing system, soil is not used at all and the plant gets what it needs from the liquid medium that it sits in. If needed, other materials such as gravel or perlite can be used to support delicate growing plant root systems. These materials are inert (do not break down or dissolve in the liquid growing medium) and will not harm the plants.


Hydroponics has a very long history – the first attempts were made in the 1600’s in Europe – and many different types of plants have been grown this way, including of course food crops such as tomatoes, strawberries, peppers and others. In our own day, this technology has been widely appropriated by weed seed growers as an alternative to soil-based growing methods.


Pros and Cons of Using Hydroponics Weed


Both types of growing methods, soil-based and non-soil based, each have positive and negative considerations:


Reduced Water Usage. While you might think that a water-based growing system would actually use more water than the traditional, soil-based approach, hydroponics growing approaches reduce water usage because the plants are able to absorb water up to 90% more efficiently than they can when they sit in soil. Why is that so? Well, when water hits soil, a good bit of it drains away (especially if growing outdoors directly in the ground). Additionally, water laying closer to the surface is subject to evaporation, especially in warmer temperatures. This water loss means that you have to frequently have to replenish the water. For those wanting to grow weed in very warm or arid regions – where the temperature is high or the available water supply is limited or restricted – hydroponics is a great solution.


Reduced Risk From Overwatering and Underwatering. In addition to a general reduction in the water demand from your pot crop, using hydroponics allows you to more tightly control the amount of water you are delivering to your plants, thereby eliminating the source of many plant problems: overwatering or underwatering. 


When planted in soil, a plant needs to draw both water as well nutrients from the soil — but it also needs oxygen as well. If you overwater your pot plants, the roots of the plant will be cut off from necessary oxygen it finds in the soil. If you underwater your plants they will not be able to pull in the water (which contains nutrients) that it needs to grow. 


In hydroponically-based growing setups, excess water can be drained away, or even aerated (the process of adding oxygen to the water). Excess water that is drained away can be saved and recirculated, thereby reducing watering expense.


Adaptable to Smaller Environments. Hydroponics is an excellent choice – perhaps the best choice – for growing indoors or anywhere you don’t have much space. If you don’t have lots of outside acreage, or you are trying to grow indoors in smaller rooms and you don’t want the hassle (and smell) of using soil indoors, hydroponics will allow you to grow your pot much more efficiently – more plants in the same area means a larger harvest. 


Healthier Plants. Cannabis grown outside can be susceptible to disease transmitted by other plants, pests and the soil it is growing in. In comparison, hydroponically-grown plants grow in a cleaner environment, usually indoors. This virtually eliminates the use of toxic pesticides. You will be able to continuously monitor your growing environment and control the amount of nutrients as well as the amount of water, that your plants need, on a day-to-day basis. The result will be a larger harvest, of stronger, healthier plants, at less expense and effort, than you could achieve using a soil-based approach to Cannabis growing.


Marijuana Hydroponic Systems: Cost Considerations


If you have the cash to spare and want to jump right in to hydroponically growing your weed, you can purchase a “grow box.” These are typically cabinets (some models can be locked for security) where your plants can be grown hydroponically. Temperature, humidity and water/nutrient delivery are all automatically controlled within the grow box.  


The cost of these will typically be several thousands of dollars, depending on the size and features of your pot grow box. While automated systems can be used in large greenhouses/grow rooms used by commercial growers, grow boxes are a good option for those who want to grow a smaller crop for personal use, either for recreational or medical consumption.


Beyond automatic growing systems, it is possible to save money by purchasing components separately. This will allow you to “piece together” a system gradually, over time. For example, you can get started with your weed seeds and get them sprouting. During that phase, you can investigate growing mediums and containers and purchase that when you are ready. When your plants are a bit older, and are starting to need more amounts of light than what is naturally available, then you can purchase grow lights and get them installed. 


This approach, where you wait to purchase, install and begin using various components only when you are need to use them, can save you from the big-dollar spend that is typical when you purchase everything you need all at once. 


Finally, keep in mind that, as a pot grower, you will have two types of expenses: one-time and ongoing. One-time expenses are typically for things like lighting, fans, pH and humidity monitoring equipment, timers, containers and the like. Other expenses will be ongoing, such as distilled water, nutrients and other items that are consumed as they are used. Your major expenses will be for your one-time purchases. But they are one-time expenses — your “true” costs will be for your ongoing expenses, and these are typically lower and more manageable than your up-front costs. 


As you get successful crops harvested, if you are selling the weed to others the income generated can help you to pay for the supplies and equipment that you need. As subsequent crops come to harvest, your profit margins (if you are selling your crop) will increase as you will only have your ongoing expenses to offset.


Assembling Your Tools to grow hydroponic marijuana


What You’ll Need


In its most basic form, you are going to need to grow your plants in some sort of container, you will need a way to deliver the water/nutrient solution to the plant, and a way to monitor and adjust the environment to ensure proper growth of the plants.


Container(s) and Growing Medium. Containers for your Cannabis can be made of many different substances – plastic, glass, metal are some of the most popular. Due to widespread availability and light weight, plastic is the more popular choice. Whatever material you choose, you need to make sure that it should keep out the light, because this will help to inhibit the growth of fungus and algae (both of which thrive and need the sun/light in order to grow).


While some hydroponic grow systems use only a liquid with added nutrients, it is also possible to make use of some sort of inert material – like gravel or perlite or coconut fiber – which sits in the growing solution, typically with the plant on top of it. Capillary action – the property of some materials to “wick” or draw a liquid – will ensure that the needed water/nutrient mix is delivered to the plant without having to manually water your pot plants as an grow-in-soil approach would require. Some growing mediums also allow more oxygen to reach the roots (because of the larger amount of air space in the growing medium) which can enhance the growth of the plants.


Environment Monitoring and Control. You will also have to give consideration to the need to monitor your growing environment – for that you will need equipment such as humidity and pH meters – as well as grow lights to provide a measured light source and also one or more fans to control the ambient breeze and to assure proper air circulation around your growing crop. In particular, growing in an attic can present challenges related to temperature and humidity. Attic spaces can get very hot and the build-up of heat and humidity will need to mitigated  through the use of fans, and in some cases, external exhaust motors.


Some hydroponic grow systems make use of complex pipes and sprayers to deliver the liquid, and aerators and filters to clean and condition it, and nutrient delivery mechanisms to automatically deliver the proper amount of nutritional additives into the water on a predetermined schedule.


Finally, you don’t want to forget your pot seeds! You should choose Cannabis varieties that adapt well to a hydroponic growing environment for best results. Varieties like Zombie Death and Agent Orange work well. 


As hydroponic pot growing means, by definition, the presence of lots of water, there is always the increased risk of developing mold, algae and plant fungus, especially if the ambient temperatures and humidity are kept at high levels. A good way to lower your risk is to grow Cannabis varieties that are mold and disease resistant (like Gorilla Glue).


Planning Your Grow Room


Before you set up as a pot grower, you need to give first consideration to your “grow room.” This is the area that you will dedicate to growing your plants. Of course, those growing Cannabis outdoors don’t have a grow room, but unless you are going to use a separate greenhouse – which are definitely expensive to build – you will be growing your crop indoors if you are using hydroponics.


Growing on a Budget


Size: The first thing you will need to think about is how much room you will need. Keep in mind that you are going to need space, not just for the plants themselves, but all of your equipment like lighting and fans and testing equipment. You will also need storage space for supplies like nutrient solution and an area for drying and curing your pot once you have harvested it. 


Obviously, as your pot plants grow and mature they will take up more and more room – depending on the variety the Cannabis plants may grow in height (getting taller) or girth (spreading out more from the sides). For this reason your grow room should allow for plenty of space between the plants so that air can circulate properly between them, and also be able to accommodate their height as they grow taller. As they grow taller they will typically be moving closer to your lighting equipment, so you should be able to maintain a safe distance between your grow lights and the plants so that they do not suffer from leaf burn, or get dehydrated.


Lighting: Speaking of lighting considerations, you need to remember that in addition to having the proper lighting installed, that your grow room should allow you to immerse your pot plants for up to 12 hours continuously (this will be the case during the flowering stage especially). 


The need for long periods of uninterrupted darkness, followed by long periods of continuous light means that, in most cases, you cannot grow your pot crop in areas that are lived in (if you use a self-contained growing cabinet you can, of course, have that cabinet anywhere in your home). 


In order that your grow room will be away from humans and pets, you might want to consider using a bedroom, an unused den or part of your basement as your grow room. Attics can be used also, as long as you properly control for heat-build up (or excessive cold in the winter if the attic is not heated otherwise).


Be a Smart Shopper: Once you have decided on the location of your grow room(s), you’ll need to begin shopping for your equipment and supplies. Remember that with a hydroponic growing system you will be putting your plants in water, not soil, so your growing containers should be watertight, do not allow light to enter (to prevent mold and fungus from developing) and very sturdy. It is not necessary, however, to always purchase brand-new equipment. 


Look on auction sites like eBay for previously-used equipment that is now being sold at a discount. Suppliers to the pot growing market may charge a premium for new equipment –  but you might find an advertisement in your local newspaper for someone selling their equipment, so keep your eyes open and don’t be in a rush to purchase everything at once. 


Another way to reduce your costs on equipment and supplies is to network and converse with other growers. Occasionally you may find a grower who is expanding and needs to invest in more or better equipment as their operations grow in size. They may be willing, for example, to sell you their starter-size nutrient delivery system when they upgrade to a larger setup. Even if they are not selling, some of your fellow growers may know of others who are. Approached respectfully, those growers may be willing to give you, the newbie pot grower, some help in saving money on your first equipment/supply purchases. For more information on growing Cannabis on a budget see


Preparing Your System


The heart of any hydroponics setup is, of course, the water/nutrient delivery system that you will be using. But before your system is installed, you should prepare your grow room by:

  1. Taking everything out of the room
  2. Removing any carpeting (you don’t want wet carpets!)
  3. Cleaning all surfaces – walls, floor and ceiling – to remove dust, grime, mold and pests
  4. Installing your grow lights (they are easier to put up before your plants and equipment are moved in)


Once your grow room has been prepared and you have your hydroponics system delivered, you need to install it (or have others do this work). There are two basic approaches to hydroponics: One type of system (a static solution system) allows your plants to sit in a container of nutrients/water. Some systems will add air via an aerator (to make sure that the plants get the oxygen they need) but some do not aerate. The other approach allows the water to flow past the plants (a continuous-flow system).


Whatever your approach, it is best to get all your equipment up and working and test it – checking for leaks especially – before you move in your pot plants. As hydroponics require the use of water, you should make sure that you have proper drain-off of liquid when you need to replace it. Some hydroponic growing systems make use of a large tank which is used as a reservoir to store water to be delivered to your plants when needed. 


Completely set up your system and add water (you don’t need to add nutrients until you place the plants). Start up the pumps and check that your water is circulating properly. Look for droplets on the tubing, especially where there are joints, as water build-up means that you have a leak.


It might not be a bad idea to let your newly-installed system run continuously for a few days (without the plants) so that you can be assured that there will not be issues with its functioning.


Once you have verified that your hydroponic pot growing system is functioning as it should, then it’s time to:

  • Place the Cannabis plants into their containers
  • Add initial nutrients as recommended
  • Bring in your other equipment – fans, pH and other monitors, etc.
  • Start up your lighting and make sure that your light timers are set to deliver the proper amount of light for the current phase of the growing cycle.


Hydroponics vs Natural Growing


An important question – and it generates a lot of “heat” in the Cannabis growing community today – is which approach to growing pot is better: growing in water/liquid (hydroponics) or growing in soil (so-called “natural” growing). Which is better?


Actually, there is no answer that fits everyone. It is much better to ask which pot growing method is better – for whom? And better when?


It is probably true that the vast majority of individual pot growers began their journey by learning how to grow pot in soil – the natural growing method. The reasons are obvious: In nature, most plants are found growing in soil, not water (which is a non-traditional way to grow plants). Soil is widely available, the use of soil as a growing medium allows you to grow outdoors if you wish, and the startup costs associated with natural growing are much lower than when you grow hydroponically.


Another important consideration is that with a hydroponic system you must carefully monitor oxygen and pH levels of your water, and must be very careful to deliver the exact amount of nutrient additives to the water. Less experienced growers may find it easier – at least initially – to grow their Cannabis in soil, especially if they have experience in growing other types of plants – flowers and food plants in gardens.


Despite the advantages, more experienced Cannabis growers sometimes move into hydroponics. There are some significant advantages, especially for growers who are growing for commercial distribution, to using a hydroponically-based system. Hydroponically-grown Cannabis will mature quicker and will yield a larger harvest than using a soil-based approach. Faster growing time means the possibility of having more harvests per year, especially since the plants will be grown indoors where the environment can be controlled. 


Compared to growing pot in soil (especially when it is grown outdoors), growing hydroponically also means reduced damage to plants from pests or disease. Hydroponically-grown pot will be free from infestation from weed plants. Hydroponic systems actually use much less water than when plants are grown in soil, and if you are growing a large crop this could mean a significant lower out-of-pocket cost for water. Hydroponics are the better choice than trying to grow in soil – especially outside – in arid regions or when hot climates quickly dry out the soil, necessitating frequent watering.


A more detailed comparison of the pros and cons of each approach to growing pot can be found at this page:


Growing Your First Cannabis Crop


Choosing Your Grow Medium


An important aspect of any hydroponics system for growing Cannabis is the “grow medium” that you will be using. The grow medium is the substance that is submerged (either partially or totally) in the water/nutrient mix, which the growing plant roots can attach to. Attaching to the grow medium helps to support the plants and also can assist with the delivery of nutrients and oxygen to the plant.


Some of the most common grow mediums include:


Vermiculite: This is a mineral which has been heated until it expands and forms very light, pebble-sized rock. It is similar to Perlite, but Vermiculite holds more water (and nutrients suspended in it) and is a very efficient way to grow plants.


Wood fiber: Your Cannabis plants, if desired, can be grown using wood slivers – Excelsior is an old-time packing ingredient used in packaging years ago, which is sometimes called “wood wool.” 


Rock wool: This is a rock material that is heated until it melts and is then spun into fibers/filaments. This material supports your pot plants well, and is very efficient in holding and transporting lots of water and also oxygen to the plant root system.


Coco Coir: As its name suggests, this grow medium is manufactured from coconuts. The long outside hairs of a coconut are first removed, the inner shorter fibers and small particles are combined to make coco coir. Before it can be used with your pot in a hydroponics system, the coco coir is processed further to remove ingredients that would be harmful to the plants. Properly conditioned, high-quality coco coir has the capacity to hold tremendous amounts of liquid, and it is naturally pest- and disease-resistant. You can find a very detailed discussion about coco coir (also called coir peat, cocopeat or just plain coconut fiber) over at our page here:


Keep in mind, though, that pot grow mediums cannot be re-used unless they are first cleaned by flushing. Some grow mediums (such as coco coir) can only be re-used 2-3 times before they begin to break down and must be replaced. Some grow mediums like sand really can’t be re-used at all (pebbles may have issues as well, with bits of the roots actually growing into the inside of the pebbles, which you can verify if you take some of them and break them open). Sand, gravel and the like are favored by some because they are cheap to purchase, and if you live near the beach they can be taken from the beach freely (although some locations may have ordinances against removing sand from their beaches, so do check with the authorities first, especially if you will need to use large amounts of those materials.)


Passive Hydroponic Systems


While some hydroponic pot growing systems utilize moving water that circulates via a pumping action, other systems use a “passive” approach. Passive hydroponic systems feature the growing plants which are grown on (or in) a grow medium. Water (and the nutrients it contains) reach the plant via capillary action rather than by being pumped. If your pot crop has suffered in the past because of root rot, switching to a passive hydroponic system reduces the risk of that happening as more air reaches the plant.


Static Systems


A variation on a completely passive hydroponic system is a static system. It is called a static system because the water is not being pumped but the plant (or several plants) are suspended in the nutrient solution. Some setups may aerate the water while it is in the container – but unlike the passive system outlined above, the static solution culture, do not use a growing medium (fibers, rocks, gravel, sand, wood wool, etc.) to channel the liquid. Instead the plant sits in the solution. When the water and nutrients drop below a stated level, the water and/or nutrient solution is replenished.


Best hydroponic nutrients for marijuana

Using the proper nutrition additives is of critical importance to the success of any hydroponic pot growing system.


When plants grow in soil, of course the nutrients that the plants need are drawn directly from it. Organic matter present in the soil decays and releases nitrogen, potassium and other substances. Water in the soil allows those nutrients to be delivered to the plant system via its roots.


However, soil does not typically deliver all the nutrition that a plant needs, or the nutrient levels may not be properly balanced to promote optimal growth (too much of one thing, too little of another).


In hydroponic growing, the nutrients (fertilizer, if you like) are suspended in water, not soil. For that reason, these nutritional plant additives must be water-soluble if they are in a granulated form, or already in a liquid state.


Keep in mind that with hydroponics the nutrients in the liquid are delivered more directly, and can be absorbed more quickly by the plants, than when they grow in soil. This means that if you over-fertilize it will impact the plant negatively very quickly – so continuous and rigorous monitoring is necessary, especially  as plant interactions with various fertilizers can change the pH or levels of nutrients very quickly. Reputable nutrient additives have a good balance of both macro- and micro-nutrients (macros are needed in larger quantities than micros).


This is a big subject, so if you need further help please check out this resource page on fertilizing Cannabis plants:


Maintaining Your Hydroponic Grow for the Future


Hydroponic Feeding Schedule


So your grow room has been prepared… your Cannabis hydroponics have been set up and tested and your first crop has been started… congratulations on getting this far!


But of course, this is just the beginning. Now that your hydroponic grow has started, you need to continue to monitor your growing conditions and adjust water/nutrient levels as necessary.


This is the really tricky phase, as your plants need a spectrum of nutrients to grow, and they must be administered in the proper amounts and at the proper time.


But growers of pot seeds are ready to help you out. With your shipment will be a feed chart which will outline exactly what types of nutrition your weed seeds will need, and when – at what time – those nutrients should be administered.


For the novice pot grower, you can rely on a “simple” feed chart which will help you to grow Cannabis that is of typical size and results in a typical harvest size. More experienced weed growers, however, can rely on an “expert” feed chart which typically presents a longer list of additives that can be added to your grow over its life cycle to help improve the size, and health of your plants, and ultimately to increase the size of your harvest. The additional nutrients can also improve the taste and aroma of your weed, and also accelerate its growing cycle. 


Over time, as you gain experience in growing your pot, you will learn what nutrients are most beneficial to your plants. As you experiment with various nutrients, varying the amounts and the timing, it is essential to maintain good records. Some growers will keep a “grow diary” or journal that gives you a place to record different formulas you are using currently, and also be a place to record when you feed your plants, as well as record how the plants react to the treatment, problems encountered and other details.


Equipment Needed for Proper Cannabis Feeding. One critical piece of equipment you will need is a PPM meter. PPM meters determine the amount of suspended nutrients in a solution by checking its electrical conductivity. A PPM meter is essential to make sure that you have not over-fed or are under-feeding your plants.


A pH meter is also essential. Monitoring your pot plant growing medium for its current pH level is necessary because Cannabis must be grown in liquid  kept at the proper pH range in order to ensure a problem-free growing experience.


Nutrients must be delivered to your plants in exact quantities – no more and no less. This means, in most cases, that the supplement must be added to a fixed amount of water in a predetermined amount. Proper ratios of nutrient-to-water must be maintained, so you will need measuring spoons and cups as well as water storage containers to hold the water to which you will be adding the needed supplements.


If you can afford to do so, we recommend that you purchase nutritional supplements in larger amounts as that will help you to save money. You are going to need to have some sort of shelving to store your nutrients, measuring spoons, mixing containers and testing equipment. 


When planning your grow room you should give consideration to the amount of space you will need to reserve for equipment and supply storage – and whether or not you will store these items near your plants or in a separate location. To keep expenses to a minimum, second-hand shelving can easily be purchased or borrowed. Your shelving and storage area could be just about anything: workshop shelving from your garage, old bookcases, a spare kitchen table. It does not need to be new or good-looking, just functional to meet your needs. 


If your existing grow room is maxed out with your crop, you can store your supplies and equipment elsewhere. Do note, however, that if you have small children on the premises, your storage arrangements should allow you to keep your plant additive supplies out of the hands of little ones. If you opt to have a separate storage area, a closet that can be locked will provide safety from accidental opening of containers (and possible poisoning) by small children.


If you need help in developing your hydroponic feeding schedule, a detailed breakdown on the equipment you will need, how to mix your additives, proper pH levels, how to read a feed chart and other important topics, you can find it here: (


For further researching off-site, you can also check out these informative links: (This link has lots of good photos as well.) (This is a very well-researched, deep-dive, with a good discussion – with photos – of growing equipment as well as an excellent discussion of the different types of hydroponic growing systems available today. A really excellent read.) (This resource article will give you pointers to help you to properly dry and cure your Cannabis once it is harvested. Only when weed has been properly dried and cured can it be put into long(er)-term storage.)

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