How to grow hydroponic weed?
Cannabis is a hardy plant that can adapt very well to different conditions so that it can be easily grown on almost all plant substrates. The most common methods are growing in soil or in hydroponic systems with substrates such as rock wool, coconut, expanded clay or Mapito.
Due to the benefits of using a hydroponic system, growing hydroponic weed has become very popular. However, to novice growers, it may sound off-puttingly technical.
No worries, we tell you exactly how to grow hydroponic weed including the best hydro systems and nutrients.
What is hydroponic weed?
Hydroponic is one of the most used methods of growing cannabis and is a very old cultivation method – archaeologists believe that hydroponics was used in the Hanging Gardens of Babylon. There are several types of hydroponic systems, but all are based on the same principle. The idea is simple; it is based on making the nutrients available to the plants by quickly absorbing fertilisers in an inert substrate such as rock wool, expanded clay or Mapito.
How it works
By using an automatic irrigation system, either recirculating (the nutrient solution is reused) or waste-to-drain (the excess nutrient solution is not reused), the cannabis plants are optimally supplied with nutrients. When using expanded clay, it is imperative to stabilise the pH of the substrate to avoid problems with the pH during the grow. If the expanded clay is not stabilised, many difficulties arise for the plants, and they will not be able to absorb the nutrients sufficiently. Also, in recirculating systems, when using unbuffered expanded clay, there are fluctuations in the nutrient tank, which can also lead to over- or under-fertilisation.
In recirculating systems in which the nutrient solution keeps leaving the tank and running back, the pH and EC value can be easily changed by an unbuffered or contaminated substrate. These factors also play a role in waste-to-drain systems, albeit a smaller one.
It is essential to point out that in these systems, the roots are exposed to the air, and constant irrigation is necessary so that the plants can develop without problems and do not dry out. As soon as a lack of moisture stresses the roots, they are severely damaged because they have no protection as in Coco substrate, in which the root ball is less exposed to the air and therefore dries out much more slowly than with expanded clay. On the other hand, if these factors are under control and no mistakes are made, the growth really explodes in such a hydroponic system.
The irrigation methods of the hydroponic systems sometimes differ enormously. There are systems like the Dutch Pot which have permanent 24-hour watering. Some growers water their plants every 15 minutes; others prefer watering them for 15 minutes every hour. Depending on the selected system, an optimal irrigation program must be set, just like when growing in rockwool.
Every grower has to find the ideal watering time for the grow, as this depends on several factors: temperature, humidity and ventilation. If the substrate dries out quickly, more waterings must be carried out, each with the development phase and needs of the plants’ optimal EC value. In hydroponic systems with rockwool or expanded clay, the nutrient uptake of the cannabis plants is more effective than in Coco, which is why the EC value should be slightly lower. The plants must also be checked every day to find an optimal EC value for each strain.
Advantages of growing hydroponic weed
Growing weed in a hydroponic way offers some serious advantages. Let’s dig into that deeper!
1. Complete control of nutrients and pH value
Hydroponics allows you to control the nutrients your cannabis plants need completely. Dilute them with water and add them to the tank so there is zero waste, unlike adding nutrients to the soil which is comparatively ineffective as some of the nutrients always fail to make it to the roots. You can calculate accurate nutrient measurements to guarantee that your weed plants receive exactly the right amount each day. The risk of root burn from inadvertently giving too much fertiliser is eliminated. Many strains of cannabis plants require a correct pH value to grow properly, and again, hydroponics ensures that the guesswork is removed when it comes to testing the pH value.
2. Increased yields
The effective fertilisation leads to improved growth and better yields, the end goal of all weed cultivators. Your precious plants don’t have to waste energy trying to get nutrients from the soil. Hydroponics means that they are free to focus on putting their energy on developing strong stalks and lovely leaves and buds.
3. A better way of using space
A hydroponic setup uses less space as the soil needs a lot of space for the roots. You can group your plants more closely together, and more plants mean more weed, once the flowering season begins! It’s also less messy than a soil-based system, no need to spend ages sweeping spilt compost from floors.
4. The roots are visible so you can quickly diagnose problems
Observing the root system is an excellent way to spot signs of nutrient deficiency or stress as problems are usually revealed more rapidly than the parts above ground. If the roots are not white, you need to take action – brown or dark roots are only seen in unhealthy plants.
5. Speedy growth rates
Hydroponics provides direct access to the nutrients your cannabis needs, close monitoring of pH and constant oxygen supply. As long as you have adequate lighting and good temperature control, plants will grow faster than plants that grow in soil. They are supplied with everything they need so that practically no energy is wasted. Plants which grow healthy and vigorously are also more resistant to diseases.
6. No need to worry about pests and diseases
Many pests and diseases thrive in soil. A hydroponic system instantly offers the answer to all these risks.
Disadvantages of hydroponics
Besides the advantages of growing hydroponically you have to be aware of the disadvantages in order to decide if growing hydroponically is the best option for your culture. So what are the disadvantages?
1. Initial investment costs
The cost of the equipment is more expensive than a crop that uses soil. However, after several successful crops, you will almost certainly realise that the investment is worth it.
2. Learning curve
Although hydroponic cultivation is not difficult, it requires a solid plan of action. You learn it by doing it so take your time and enjoy the learning process
Building a hydroponic system for growing weed
The following list encompasses all the apparatus you need to build a basic indoor hydroponic system. We recommend buying each item separately at the lowest possible price, so you have more funds for expensive but essential lighting and heating.
This is what you need
- A grow space
- Growing medium, such as coir or rockwool
- Mesh or net planting pots
- Hygrometer to measure humidity and a thermometer
- A carbon filter
- LED Lights
- A ventilation fan and an oscillating fan
- Ducting tubes
- Pump or airstone
- Lighting hangers
- Hydroponic reservoir and tray
- pH and PPM meters
Best hydroponic medium to grow weed with
One of the first things you need to do is choosing a growing medium — this is a substance that supports the axis between the stem and roots. The growing medium allows the roots to descend into the water to access nutrients. There are many types of medium, each with its own set of advantages and disadvantages. It’a matter of experience to see which is best for you.
1. Clay Pebbles
Clay pebbles are highly popular as they are inexpensive and easy to use; just watch the pH levels as they may need to be altered because of the clay. Place in a basket with gaps for the roots to penetrate into the water.
2. Rockwool or mineral wool
Rockwool is also a common choice and is a substance made from spinning fibres from basaltic rocks into a wool texture. Rockwool is really good at retaining water, which enables proper hydration of the top root system. However, it is not very environmentally friendly and is also potentially harmful to your health.
Perlite is an amorphous volcanic glass that swells when it is exposed to high temperatures. You may have come across it in compost to prevent compaction and to provide aeration, and it serves the same purpose when used in hydroponics.
4. Coco Coir
Coco coir is the hairy fibre from coconuts and enables proper aeration and moisture retention. Coconut fibres also help protect roots from being affected by plant-stimulating hormones.
Best hydroponic system for weed
All systems use a water solution enriched with nutrients. However, some installations vary according to various factors such as circulation and water exposure. You can buy hydroponics setups online, or you can save money and build one yourself if you have DIY expertise.
1. Deep water culture
Deep water culture is an excellent place to start for beginners and is probably the least expensive option. Cannabis plants are placed in buckets filled with a nutrient solution, and an air pump provides a constant supply of oxygen.
2. Flood and drain system
This type of system consists of several buckets hung over a growing tray which has two waterways; an inlet and outlet, both of which are connected to an external tank that contains nutrients. A flood and drain system is a very stable method of cultivation and is highly recommended for novice growers who need a secure hydro system that will still provide great results.
3. Drip system
A drip system is an active hydroponic system, which means that it utilises a pump to supply your plants with regular nutrients and water. It is also known as a micro-irrigation system. The system features small emitters to drip the nutrients directly onto your cannabis plants.
4. Nutrient film technique
If deep water culture is similar to growing cannabis plants in a pond, then the nutrient film technique equates to growing weed over a river. This system involves placing weed plants into an angled tube so that water can flow in one side and leave the other via gravity. The roots descend into the tube, where they are exposed to the flowing water. The water enters from a tank with a pump and airstone and returns once the cycle is complete.
5. Wick system
A wick system is a simple hydroponic setup that features a growing tray. A tank of water is placed underneath from which several wicks exit and enter the growing medium. Water flows up the wicks and hydrates the medium without a pump being required.
Best nutrients for hydroponics
In hydroponics, the nutrients the plants need are mixed with the water the plants receive. Here you have two options:
1. Liquid food
Liquid food needs to be mixed with a certain amount of water. If the plant then absorbs water, it also absorbs nutrients, allowing it to grow.
The capsules are slightly different. These have to be mixed with water, but they will sink to the bottom anyway, no matter how much you mix. When the plant is hungry, it secretes a specific acid that ends up in the water and causes the capsules to disintegrate. The nutrients in the capsules are thus released and mix with the water. The nutrients are then absorbed in the same way as with liquid food. If the plant absorbs some of the water, it automatically absorbs the nutrients in the water. The handy thing about this system is that you can easily give the plant a lot of nutrients, without running the risk that the weed will immediately consume everything.
Best strains for hydroponics
Choosing the right strain is an important consideration when using hydroponics. Plants can absorb nutrients very quickly, which frequently leads to ultra-rapid growth. If space is at a premium, you would be well-advised to opt for a small, bushy Indica rather than a lanky Sativa that will quickly be out of control.
Smaller and bushier varieties are great for indoor hydroponic systems for several reasons. Firstly, it will allow you to grow types of weed plants within a smaller space, enabling greater variation and yields. If your plants do decide to take off, you’ll have enough room to cope with a sudden upsurge in height.
Here are two strains that are brilliant for hydroponic growing:
Anyone who wants to try and grow Blue Dream should be warned – nutrients are very important and potentially expensive as this cannabis strain is famous for its hungry appetite.
One of the many reasons why Blue Dream is an excellent choice for hydroponics is because the nutrients it craves will be optimally absorbed in water. Less waste and less cost. Blue Dream is highly recommended as it offers brilliant highs and effectively treats depression.
White Widow is one of the most potent Ruderalis hybrids currently available on the market with a downright great fruity aroma and taste. Its highs make it a good strain to be used in combating anxiety, stress, anxiety and sleep disorders, a perfect strain for ultimate relaxation after a stressful day. It offers average yields for an auto-flower, but the result is absolutely worth it.
The White Widow Auto is ideal for hydroponic cultivation – and a perfect strain for novice growers due to its robust nature, high natural resistance to mould and its ability to withstand almost any climate. The White Widow Auto has a small to medium build that tends to form one large, dense central bud whose growth and density can be stimulated by pruning the lower branches in time so she can put all her energy into the tops.
Tip: check our feminized White Widow strain seeds
Hydroponics can seem daunting but the effort is worthwhile
Hydroponics can seem off-puttingly complex to a novice grower. All the various components and methods are a lot to take in. Our advice is to start small, select a reliable strain, and regularly tend to the needs of your plants. Using a hydroponic system is very rewarding, and your hard work will pay off with quick harvest time and generous yields.
It’s important to remember that, to produce good weed using hydroponics; it is still vital to use a reliable seed source, such as Weedseedsexpress. You could spend lots of money on expensive hydroponics systems but fail to produce a good crop of weed. A potent strain of genetics is essential for a seed to reach its potential and blossom into high-quality buds filled with sticky resin.
Contact Weedseedsexpress and browse our extensive selection of high quality cannabis seeds.
Curious how to grow hydroponic weed? Check it out! We explain what hydroponic weed is, how to build the best setup and what you need!
How to Germinate Cannabis Seeds in Hydro
We have a cannabis seedling germination page which has everything you need to know about all the different germination methods, but this tutorial is different. In this hydroponic seedling tutorial I’m going to share exactly how I do my seeds from beginning to end in a DWC/bubbleponics setup!
Just follow these instructions and you’ll end up with healthy, fast-growing plants that germinate in just a few days. It’s pretty much fail proof!
Learn How to Start Seedlings So You Can Grow Hydroponic Cannabis Plants Like This!
1.) Get Cannabis Seeds
There are a few different ways to get cannabis seeds, with the most common being ordering seeds online and growing seeds you find in weed that you buy. Learn how to research and find the right strain.
Here’s a picture showing several healthy and viable cannabis seeds
2.) Germination for Hydroponics
I’ve tried a bunch of different germination methods over the years, and the technique I prefer is for hydroponics is starting with the “Paper towel method” to germinate, putting the germinated seeds into Rapid Rooters, and installing the Rapid Rooters directly into reservoir. Lots of other germination methods as well, but this has worked best for me!
Paper Towel Method
This method is hard to mess up if you follow the instructions!
- Place your seeds inside a folded wet paper towel, and place it between two paper plates (or regular plates) so that they don’t dry out.
- Check on your seeds every 12 hours but try not to disturb them. When they’ve germinated, you’ll see the seeds have cracked and there are little white roots coming out.
- They should germinate in 1-4 days, though some seeds can take a week or longer (especially older seeds).
- Keep them warm if possible. One thing you can do to get seeds to germinate a little faster is to keep them in a warm place (75-80°F). Some people use a seedling heat mat but in most cases that’s unnecessary.
These seedlings were sprouted using the paper towel method!
3.) Place Germinated Seed in a Rapid Rooter
The Rapid Rooter should be cut open lengthwise
Gently place the germinated seed inside, root down
Most seedling plugs will go back into place easily, and you’ll barely be able to tell it’s been opened ?
4.) Prepare Hydro System for Its New Guest
If you haven’t put your hydroponic system together yet, now is the time! Make sure your pumps are all running, and that you’ve made a reservoir with seedling-strength nutrients. You need a home to put your new plants!
Hydro Tips & Hints
- Air bubbles – have lots and lots of bubbles in your water reservoir. That means your air pump needs to be on all the time for the full grow. The main benefit of hydro is your plant roots are getting an unlimited amount of both water and oxygen. This is achieved by dissolving a lot of air into the water via an air stone and air pump. In order to get the fast growth, you want a lot of bubbles! A highly-oxygenated tank is also far less likely to get root rot, or suffer from other unwanted organisms growing in the reservoir!
- Hydroguard – This supplement contains a specific bacteria that was first found in rice paddies in Japan in the 40s! It’s been common in Asia for years but only in the last several years has it been available in the US from a company called Botanicare. I highly recommend, even insist, that all hydro growers get this cheap-but-effective supplement to keep plant roots healthy!
- Add seedling level nutrients from the beginning. A lot of growers, especially soil growers, will tell you not to add any nutrients for the first few weeks of the plant’s life. That makes a lot of sense in soil, because there are lots of nutrients contained in the soil itself for your young cannabis seedling, and giving more right at the beginning can end up giving way too much for such a young plant. However, in hydro, the only nutrients your seedling gets is what’s in the water, plus what little was contained in the seed itself. Because of that, I highly recommend giving seedling-strength nutrients to your plants from when you first fill your reservoir. Seedlings grow a LOT faster with light levels of nutrients than if you only give plain, pH’ed water at first.
- Always check the pHfrom the beginning of your plant’s life to end the of your plant’s life
5.) Install Rapid Rooter and water the seedlings until roots reach the water reservoir – Turn on light to keep seedlings warm for best results!
Make sure to always keep the Rapid Rooter moist but not soaking wet.
If you have a top-feed, place the tube near the bottom of the net pot so the water isn’t soaking the seedling’s roots. You just want water dripping out the bottom so the root can use it for oxygen and water until it’s fully established in the reservoir.
Add your Rapid Rooter(s), and fill around the edges with extra clay pellets to hold each one in place.
Since your seed has already sprouted and been in placed into the right growing position, it’ll often pop its head out within just 12-24 hours! Sometimes you see just the leaves, but occasionally you actually see the seedling push the shell above ground. I keep the grow light on even before the seedling appears. It helps keep it warm and guide it toward the light.
When this happens the shell usually falls off on its own as the seedling grows!
The Rapid Rooter in this picture is a little too wet, which makes the seedling prone to “damping off.” If you ever notice the Rapid Rooter actually looks wet or shiny, it’s too much water. Try turning the top-feed off every few hours, or hand-watering the seedling at first. Too much moisture can kill!
Don’t use a humidity dome on seedlings unless it’s very dry where you live. If you do use a dome, consider keeping a vent open and watching the humidity. A young seedling doesn’t require high humidity, and they tend to get “wet feet” and stop growing in constantly wet conditions.
Now that your seedling in in the tank, it’s time to learn how to….
6.) Take Care of Hydro Seedlings
Here are tips for taking the best care of hydroponic marijuana seedlings:
- Leave roots alone as much as you can with young seedlings in a hydroponic setup. It takes them a little while to get all established in the tank, almost like a fish, and during that time seedlings are much more sensitive to their roots being touched or being moved around. If at all possible, try to let the seedling grow in the same place without being moved for at least a few weeks until you put them in their final home, or even just start them in their final home!
- Avoid reservoir changes for a few weeks if you can – Going along with what I said before about leaving the roots alone, I’ve found that young seedlings often don’t respond well to reservoir changes. Instead of changing the reservoir, just top off with half-strength vegetative nutrient water until the plant is at least 3 weeks old. It won’t be using enough nutrients to mess with the ratios, and as long as you maintain the pH and use Hydroguard your young plant will be fine with being topped off.
- Check the pH dailyto prevent nutrient deficiencies
- Warm but not hot temperature– I recommend hydro growers aim for 75°F, and try to stay between 73-80°F.
These seedlings are a few weeks old, and the grower plans to move them all to the
This is a time-lapse video of a cannabis seedling sprouting and growing over 13 days.
Cannabis seedlings just getting their bearings – try to avoid moving or disturbing them until they are growing fast, with new leaves every day!
Big cannabis plants ready to switch to the flowering stage
I thought hydro plants liked it cold?
Just like in soil, cannabis plants in hydro tend to grow faster in relatively warm temperatures. This is a somewhat controversial statement because a lot of hydro growers prefer to keep their temperature lower in the grow space to help prevent root rot. In fact, there are some growers right now who are reading this and shaking their heads at me.
There’s good reason to believe that hydro plants would grow better with a cool reservoir. For example, the bad microorganisms that make root rot don’t survive well at lower temperatures. Additionally, water can physically hold more oxygen at lower temperatures, which seems like it would be great for faster plant growth. Because of this, lots of growers will AC their room to 60°F, and/or get a water chiller to cool their water reservoir to a similar temperature.
I do agree that if the temperature is above 80°F, your plant is a lot more likely to get root rot. However, I personally have not found that cool temperatures are adequate to prevent root rot. Even if the temperature is 60°F, you still need lots of bubbles and a “good bacteria” supplement like Hydroguard to prevent root rot in many cases.
I’ve seen several growers buy a water chiller and still get root rot. So I personally don’t believe cold temperatures are the best way to go to keep roots healthy.
The other reason I recommend to keep it warmer is because the plants just grow faster around 75°F in hydro. If your roots go from 60°F to 75°F, you’ll see the plants start growing faster in just a day or two, just like how plants in soil grow faster when it’s warm!
Just like in soil or coco, cannabis plants in hydro grow fastest when it’s a little warm, around 75°F!
Although there may be more oxygen dissolved in the water at lower temperatures, at least in my grow tent that apparently isn’t the limiting factor to growth, because plant growth speeds up at warmer temperatures.
I’ve found that if the grow space feels cool to you, it also feels cool to your plant most likely, and it may not be growing to its full potential. Some Sativa strains are particularly sensitive to the cold, though some Indica strains from cold climates will still thrive at lower temps.
Autopsy: Why Aren’t My Seeds Sprouting?
If your seeds still aren’t sprouting and growing properly, consider the following factors.
If there’s no germination at all…
- Temperature may be too hot or cold – aim for 75-80°F
- Too wet – seeds and seedling roots should always be moist, but should not stay wet
- Too dry – if a root dries out the seedling can die!
- Bad seeds – It might not be you, it could be the seeds themselves! How can I tell if seeds are viable?
If seeds sprout, but then stop growing…
- Temperature is too hot or cold – aim for 73-78°F
- Too wet – even though your plants are growing with root directly in water, new seedlings don’t like “wet feet”. They don’t like for it to be too wet near the seed for too long, so make sure your Rapid Rooter or growing medium nevers looks shiny or muddy, as that means there’s too much water! Young roots that stay too wet for too long start to get mushy and die. For this reason, it’s also usually recommended to avoid using a humidity dome with seedlings unless your air is dry. Although clones love humidity domes (they need water from the air because they don’t have any roots to get water), seedlings like it a little more dry or roots tend to get mushy.
- Too dry – less common unless you live in a very dry area, but sometimes your medium dries out too fast if you’ve got a heavy-drinking, fast-growing seedling!
- Too much light – if the seedlings get blasted with high levels of light right away, it can shock them. They may need some time to adjust to higher light levels. Simply starting your grow light a little further away that normal is usually enough.Think sunny window at first, and start ramping up after a week of healthy growth.
- Not enough light – if seedlings are growing long and stretchy without growing new sets of leaves, it means it wants more light.
- No light for more than a day – if the sprouted seed doesn’t get light within 24 hours after sprouting, it may die. Once seeds are sprouted, get them in a Rapid Rooter and under at least some amount of light as soon as possible!
- Roots damaged – If somehow your roots got damaged, it can sometimes stop the seedling from growing
Unfortunately sometimes you will never know why certain seeds just don’t thrive! It’s all part of nature ?
How to Germinate Cannabis Seeds in Hydro We have a cannabis seedling germination page which has everything you need to know about all the different germination methods, but this tutorial is