FastBuds seedbank #1 with 9695 diaries and a rating of Growdiaries 8.8/10 on GrowDiaries
Growdiaries 8.8/10 with 10011 diaries on GrowDiaries

How to Grow Autoflowering Cannabis Plants in a Hydroponic Setup

A hydroponic setup is the way to go if you want to grow really frosty flowers with a high amount of terpenes.
08 June 2022
15 min read
How to Grow Autoflowering Cannabis Plants in a Hydroponic Setup

Contents:
  • 1. What are ph and ppm levels?
  • 2. Measuring and adjusting ph and ec levels
  • 3. Hydroponic setups
  • 3. a. Hydro setups: ebb and flow & continuous flow
  • 3. b. Hydro setups: deep water culture (dwc)
  • 3. c. Hydro setups: shallow water culture (swc)
  • 3. d. Hydro setups: nutrient film technique
  • 3. e. Hydro setups: aeroponics
  • 3. f. Hydro setups: drip irrigation and continuous drip irrigation
  • 3. g. Hydro setups: wick system
  • 4. Best autoflowers to grow in a hydro setup
  • 4. a. Orange sherbet auto
  • 4. b. Wedding cheesecake auto
  • 5. Most common mistakes when growing hydroponically
  • 5. a. Ignoring ph levels
  • 5. b. Using improper nutrients
  • 5. c. Incorrect lighting
  • 5. d. Not cleaning properly
  • 6. Not ready for a full hydro setup, but want to dip your toes into the hydro world?
  • 7. In conclusion

Hydroponics is a well-known technique for cultivating soilless indoors, this technique consists of soaking the roots in a nutrient solution and lots of oxygen. Using this method means that there is no soil and plants grow in a sterile, inert growing medium. The hydroponic method provides the nutrients, water, and oxygen directly to the roots. As there is no need for massive roots or extra energy to absorb the nutrients, the plants grow much faster and bigger, here's a hydroponic grow guide and some tips to help you decide on the best way to grow autoflowers hydroponically in your growing space.

1. What are pH and PPM Levels?

Before talking about the different hydroponic setups we must advise that in hydroponic grow is essential to measure pH and PPM levels every day. We use the pH meter to know how alkaline or acidic our solution is and the EC meter is used to measure PPM levels (PPM means particles per million).

 

Autoflowering cannabis in hydro: check the ph

Use pH meter to check nutrient intake of your marijuana plant.
 

A simple way to understand it is we measure pH levels to be sure our plant’s nutrient intake is optimal. We measure PPM levels to make sure we are giving the right amount of nutrients to our plant and to ensure our plant is absorbing nutrients.

2. Measuring and Adjusting pH and EC Levels

In hydroponics, it’s essential to measure pH and PPM levels every day, preferably every time we feed our autoflowers. You should measure runoff and the solution going in, and compare. PH levels should be around 5.5-5.8. If they are too high or too low your plant will have problems absorbing nutrients. You can use a pH-adjusting solution (pH up or pH down) and measure again until it’s as close as possible to the desired amount. PPM levels go up for each stage so here’s a table to better visualize them:

Autoflowering cannabis in hydro: optimal ppm levels

Optimal PPM levels on every stage of a weed plant growth.
 

Keep in mind, if PPM levels are too low or too high, your autoflower will show symptoms of under or overfeeding.

3. Hydroponic Setups

No matter which hydroponic system you choose you’ll need:

  • a water pump;
  • an air stone;
  • a timer;
  • a reservoir;

Make sure that you pick a large enough reservoir so it can hold enough water and nutrients for a couple of weeks. The reservoir has to have a lid so your solution doesn’t evaporate. You’ll need another reservoir to hold water where you can test and adjust pH. We recommend having a third one in case one of the other two breaks. The reservoir containing the nutrient solution should be insulated so you can control the temperature. Now, have in mind that there's no such thing as the best hydroponic system for cannabis because the best one for you will depend on what suits you better and what you can afford.

Hydro Setups: Ebb and flow & Continuous Flow

This hydroponic system is quite simple and it's the most popular choice within growers because it doesn’t require too much work, it’s low maintenance, and very productive. This system is ideal for beginners. Ebb and flow works by placing our reservoir under the growing bed. The water pump turns on to fill the growing bed (where the plants are) every 15 min with our solution. When it reaches its higher level, the pump turns off and the solution is then drained through a pipe. In this setup, you can use coco fiber, perlite, or clay pebbles to support your plant. Growing hydroponically you need some kind of medium so the roots can hold themselves onto something. 

 

Autoflowering cannabis in hydro: ebb and flow and continuous flow

The hydroponic setup for Ebb and flow/Continuous Flow is basically the same with minor changes in the size and height of the drain pipes.
 

With basically the same setup as the Ebb and flow, the Continuous flow technique is the opposite. This method consists of providing a continuous flow of solution. The never-ending stream of water flows around the roots, allowing them to absorb what they need from it. As opposed to the Ebb and flow which fills all the way to the limit and then drains all at once.

 

ProsCons
Easy to buildProblems with breakdowns
Nutrient abundanceUnstable pH
Low costCan result in nutrient deficiencies

 

Hydro Setups: Deep water culture (DWC)

Deep water culture is a style of hydroponic growing that may or may not use a medium like perlite, coco, or clay pebbles. In a DWC setup, you have a reservoir filled with a mix of water and nutrients, the lid holds special pots or nets with their roots stretching down having part of them submerged in the solution, this way they have nutrients available all day long and can absorb nutrients when they want to.

 

Autoflowering cannabis in hydro: dwc

Hydroponic grow: Deep water cannabis cultivation.
 

As we know, oxygen is essential for plants, so you need to use an air stone in this setup to keep the solution oxygenated.

 

ProsCons
Faster growth Completely depends on the air pump
Little maintenanceHard to maintain water temperature
No need for a lot of equipmentPH may fluctuate a lot in smaller setups

Hydro Setups: Shallow water culture (SWC)

Shallow water cultures (SWC) is basically the same as deep water culture (DWC) but instead of growing in a bucket or big container, this system consists of a wide reservoir that’s no deeper than 20 - 25 cm, where plants get a constant flow of nutrient solution. SWC is considered more efficient in terms of space, however, it’s usually only used for clones because it’s super hard to maintain correct pH levels due to the nutrient solution and water in the reservoir needing to be monitored constantly.

 

Autoflowering cannabis in hydro: swc

Hydroponic grow: Shallow water cannabis cultivation.
 

As you may know, oxygenation is vital when growing in hydro so make sure the water is flowing properly or add air stones for the water to be properly oxygenated.

 

ProsCons
Water flow provides enough oxygenationNeeds constant monitoring
Bigger yieldsWorks better when growing smaller plants
Uses less water and nutrientsPH can fluctuate a lot

Deep Water Culture (DWC) vs Shallow Water Culture (SWC)

As mentioned, SWC is basically the same as DWC but instead of growing in a deep reservoir, you grow in a wide one so a shallow water culture setup may be more suited for growers with limited vertical space but plenty of horizontal space. Another important difference is that an SWC setup uses less water which allows you to save on water and nutrients but, due to using less water, pH levels can oscillate and the temperature of the water may fluctuate; This means that despite saving money, an SWC requires you to be precise and needs constant monitoring so it’s recommended for more experienced growers.

Hydro Setups: Nutrient Film Technique

The nutrient film technique consists of exposing the roots to the air permanently and keeping a thin flow of water along the bottom in which the tips of the roots are soaked, providing the nutrients they need while the rest of the roots are exposed to oxygen.

 

Autoflowering cannabis in hydro: nutrient film technique

Nutrient film technique in a hydroponic setup.
 

After years of utilizing this technique, growers realized the downsides to this technique which were quite bad, some growers quickly ran into problems such as root rot so they upgraded the nutrient film technique in a form where the roots are suspended in net pots which ended up being very similar to the Ebb and flow method but with thin layer of water constantly flowing underneath the roots.

 

ProsCons
Easy to inspect roots for diseasesCannot stop the water flow
Less water and nutrient consumptionWater can heat up faster than in other setups
Prevents nutrient build-upMust check regularly

 

Hydro setups: Aeroponics

Aeroponics is a technique very similar to the DWC technique mentioned previously. The setup is the same, a reservoir filled with a solution of water and nutrients. The difference is, instead of submerging the roots, we leave them hanging in midair, using a sprinkler to mist water directly on the roots every 3-5 min.

 

Autoflowering cannabis in hydro: aeroponics

With aeroponics method the roots are hanging in midair and watered directly with a sprinkler every 3-5 min.
 

The reservoir must be lightproof and waterproof which helps create a highly humid environment. There’s no need to use an air stone as the roots are literally surrounded by oxygen.

 

ProsCons
Maximum nutrient absorptionRequires constant attention
Easier to move plants aroundInitial cost can be high
Healthier plantsRequires a bit of technical knowledge

 

Hydro setups: Drip Irrigation and Continuous Drip Irrigation

The Drip irrigation method consists of having a large reservoir with tubes that is reaching each pot individually. On the tip of the tubes, there are drippers that are placed above the grow medium (this method can be used with hydroponic mediums or soil). You have to program a timer that controls the amount of solution and frequency your plants get fed. When the timer turns on, a water pump is activated, watering your plant for the exact amount of time you programmed, not a drop more, not a drop less. Normally they are watered in increments of 15 mins and for a duration of around 4 min. You don’t even have to be there to feed them. Ideally, you would be just checking if the system is working properly and that's it. 

 

Autoflowering cannabis in hydro: drip irrigation and continuous drip irrigation

This is a perfect option for beginners. Except checking on the system once in a while it doesn't require much hands-on action.
 

There is an adaptation of the drip irrigation technique called Continuous drip irrigation. It uses the same setup but instead of watering when the timer turns on, the water pump never turns off, providing a continuous flow of solution for the plant. Like in the DWC technique, this way the plants can be fed whenever they need to and will result in faster growth and much bigger plants.

 

ProsCons
Minimizer evaporation thus saving waterMust be controlled closely
Healthy soil due to optimal wateringsTubing might get clogged
Little runoff results in a richer soilEquipment must be on 24/7

 

Hydro setups: Wick System

A wick system (aka wicking) is another method used to grow cannabis hydroponically but unlike the other methods cited before, this one is relatively low-maintenance, easy to use, and can be done for cheap so it’s recommended for growers that want to start growing hydroponically but want to start with a simple setup.

 

Autoflowering cannabis in hydro: wick system

A wick system is the cheapest hydro system but it could be easier to get root rot so you have to be extremely careful.
 

This system basically consists of using the principle of capillary action to provide water to your plants so as your plants draw nutrients to the roots, the wick pulls the nutrient solution from the reservoir, basically watering the soil.

 

ProsCons
Simple and accessible for beginnersNot suitable for big plants
Minimal maintenanceNot very efficient at delivering nutrients
Uses less electricity than other hydro setupsEasier to get nutrient build-up in the soil

 

This is a huge benefit because it makes it almost impossible to overwater your marijuana plants, although due to the wicks being always moist, it’s possible to get root rot so it’s essential to maintain good growing conditions.

4. Best Autoflowers To Grow In A Hydro Setup

Growing hydroponically consists of feeding your plant and maintaining good conditions for the roots to grow in, just like when growing in coco or soil so any strain will do exceptionally well in a hydro setup.

Orange Sherbet Auto

If you have enough space in your grow room try cultivating one of the big yielders like our Orange Sherbet Auto. Hydroponic setup will let her fully develop resulting in a huge yield.

Orange Sherbet Auto
5 out of 5
I grew this with other fast buds strains. I'm very happy how they all grew. I use soil, 19L pots on a 20/4 light cycle. They love it.
fastman.
Verified customer
Reviewed 23 October 2020
 

Growing this strain in a hydroponic setup will let her fully develop, growing up to 150cm and producing huge yields.

Grow tips

  • We recommend LST to open up the canopy and allow light to reach the lower flowering sites, increasing yields even further.
  • It’s most likely that you’ll need to provide support to the branches due to the heavy buds so make sure you keep an eye out to prevent the branches from snapping.

Wedding Cheesecake Auto

Another great strain to grow hydroponically is our Wedding Cheesecake Auto which grows up to 130cm with several side branches, just like the Orange Sherbet Auto

Wedding Cheesecake Auto
5 out of 5
Beautiful plants, and consistent among the three. I topped all of them and got around 115g off each in 2 gallon pots. Very pleased
Breen.
Verified customer
Reviewed 9 December 2020
 

By maintaining good growing conditions throughout the whole grow cycle you can expect huge yields of up to 600gr/m2 so it’s definitely a must for hydro growers.

Grow tips

  • This strain responds very well to LST so we recommend tying down the branches early in the vegetative stage to allow the buds to develop to the maximum.
  • We recommend using bigger pots (11-12L) to allow your plant to develop to the fullest and allow your plant to show its full potential.

5. Most Common Mistakes When Growing Hydroponically

Even though you might get excited to get better yields and bigger plants, growing in a hydro setup is not super easy and it has a learning curve to be able to do it properly and successfully so here are the main mistakes that will bring problems into your cannabis garden.

Ignoring pH Levels

The pH level is vital for your plants to be able to absorb nutrients properly, if the pH level oscillates your plants will have a hard time absorbing nutrients, showing signs of deficiencies and ultimately dying.

 

Autoflowering cannabis in hydro: ph levels

Measuring and adjusting the pH levels is obligatory when growing hydroponically.
 

So to avoid this you will need to measure the pH at least once a day and with a good pH meter, remember that your plants grow thanks to the nutrient solution that feeds them so if the nutrient solution is off, your plants might not grow.

Using improper nutrients

Using improper nutrients will not only prevent your plants from growing to their fullest but can also end up clogging your hydro setup because some fertilizers may not dilute entirely and can end up clogging tubes and drains so make sure you use the best hydro fertilizers you can.

Incorrect lighting

Another super important factor is the light fixture, using the wrong kind of lighting or using a light that it’s not strong enough won’t allow your plants to perform photosynthesis properly and your plants won’t grow as strong and big as you would want to.

 

Autoflowering cannabis in hydro: led lights

Led lights produce a full-spectrum so are usually preferred by growers.
 

Now, there's a lot of debate about which ones are better, LEDs or light bulbs but the truth is that you can get really good results with both, it's just a matter of knowing how to use them but LEDs are usually preferred by growers due to their full-spectrum.

Not cleaning properly

It’s essential you clean your setup before using it and after every grow cycle because the nutrient solution can end up getting harmful bacteria or you can end up with a hydro setup full of algae so you should clean not only your equipment but the entire grow space your plants are in.

6. Not Ready for a Full Hydro Setup, But Want to Dip Your Toes Into the Hydro World?

Let's talk coco coir! Ok, so now we have been through the whole process of setting up all the different types of pure hydroponic options. And while all of them will produce fantastic results, they are pretty complicated processes that take a fair bit of effort and funds to set up, and once the setup is done the work is far from over. Hydro setups need constant attention, far more than soil grows for sure. But, is there another option? One that offers some of the ease of soil growing mixed with the obvious yield advantages that a hydro setup offers? Yes indeed! Say hello to coco-coir.

But what exactly is coco-coir, and how can we use it to grow pot?

Well, to put it simply, coco-coir is the perfect mix of both hydroponics and soil. It offers most of the advantages of both styles of cultivation with almost none of the drawbacks. It is budget-friendly, easy to work with, and offers fantastic growth potential. Coco-coir is a totally inert hydroponic medium that is made from the shaggy outer layer that covers a coconut. Do you know the stringy, almost hair-like shag that you get on a coconut? That’s the stuff. But don’t go out and start buying up all the coconuts you can lay your hands on just yet.

Since it is a totally inert medium you need to add all the nutrients just as you would with a pure hydro setup. But, unlike pure hydroponics, where the roots are suspended in the nutrient solution, the roots are held in the coco-coir which acts in a very similar way to soil. This means the roots are far more protected from not only pests, fungi, and disease infestations but also to sunlight. 

Ok, but what are the actual advantages of growing in coco-coir over hydro or soil?

We have briefly touched on some of the reasons why we love using coco as our growing medium, but let’s break it down:

 

  • Coco-coir offers Huge harvest potential and increases the speed of the lifecycle -  Plants grown in coco-coir propagate almost as quickly as with pure hydro.
  • It offers amazing root zone oxygenation -  some studies show that coco-coir holds up to 70% more oxygen in the root zone than pure soil. Root zone oxygenation plays a vital role in the speed of growth, the final yield, and potency.
  • It is highly resistant to pests, fungal, and disease infestations - The natural resistance is a huge plus for both indoor and outdoor cultivators.
  • It is renewable and environmentally friendly - Once reserved for the trash heap, these days coco-coir is being repurposed and can helo cultivators reduce their carbon footprint.
  • It requires less water and nutrient usage than soil - Coco-coir receives and drains much easier than pure soil, meaning the watering requirements of coco-coir are much lower.

 

These days, every single nutrient supplier has a dedicated range of nutrients to use for coco. They can be applied in pretty much any way you see fit, but the most common applications are either hand watering or drip-feeding. If you go down the hand watering route (which most beginner cultivators do), remember to always fully douse the coco-coir until you see about 30% of the nutrient solution runoff. Remember to also regularly check the pH of this runoff to ensure the substrate is in good shape and the root zone is in the right pH range for the nutrients to be available. It’s no good to feed perfectly pH’d water or nutrient solution if the substrate is at the wrong pH.

Are there any obvious drawbacks of using coco as the main medium choice?

As with any cultivating choice, there is a balance of advantages and disadvantages that you need to take into account before you decide on which route to go down. The cons of coco-coir are :

  • More work overall than using a soil-based substrate - While you can run an organic protocol with coco-coir, it is more complicated than using a good soil mix. Having to feed the plant with a nutrient solution is inherently more work than letting the plants feed naturally from soil.
  • Nutrient and pH issues are more common than soil cultivation - Plants in coco-coir are more sensitive to changes in the nutrient solution and pH, but thankfully they are also easier to fix thanks to the ease of flushing with coco-coir.
  • The terpene profile may not stack up against organic buds - Weed grown in coco will be strong as hell and taste amazing, but most cultivators agree that to get the absolute best terpene profile you need to use organic options.

7. In Conclusion

There's no such thing as the best hydroponics system for cannabis, all autoflowers grown in hydroponic setups can grow much taller and quicker due to the constant feeding of nutrients and water as long as you do it properly. They can develop faster and produce frostier buds with more terpenes than plants growing in normal soil, resulting in overall better quality.

We highly recommend considering these techniques and we promise the end result (if done correctly) can be infinitely better than any plant grown in soil. 

 

External references

  1. The results of an experimental indoor hydroponic Cannabis growing study, using the 'Screen of Green' (ScrOG) method-Yield, tetrahydrocannabinol (THC) and DNA analysis. - Knight, Glenys & Hansen, Sean & Connor, Mark & Poulsen, Helen & McGovern, Catherine & Stacey, Janet. (2010).
  2. Hydroponics Cultivation of Crops. - Gaikwad, Dinkar & Maitra, Sagar. (2020).
  3. The Techniques of Hydroponic System. - Mariyappillai, Anbarasu & Arumugam, Gurusamy & V B, Raghavendran. (2020).
08 June 2022