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Hydroponics Cannabis Growing Guide

Hydroponics is a method of cultivating plants, specifically cannabis in this case, in a solution of water and nutrients.

Contents:

As the name may suggest, hydroponics is a soilless method of growing cannabis using water as the primary medium. Within a hydroponic setup, cannabis plants are grown in buckets or baskets filled with an inert growing medium, and are suspended over a tank full of water. The water is filled with all of the nutrients plants need to survive and thrive, and air stones are used to aerate the tank. This basic model manifests in many different forms and systems, with different growers preferring different setups. There are many advantages to hydroponic cultivation, all of which will be covered in this article. But first, let’s delve into the history of this fascinating art form.

THE HISTORY OF HYDROPONICS

Hydroponic cultivation might initially seem like the result of modern advances in technology. But this couldn’t be further from the truth. The origins of growing plants in water goes back thousands of years into human history. The famous Hanging Gardens of Babylon, created in 600 BCE, are theorised to have utilised hydroponic principles. The region located next to the Euphrates was naturally dry and arid. It’s believed the crops of the garden were nurtured using a trickle-system starting at the river.

Moving closer in time to the 10th and 11th centuries, the Aztec civilisation was also known to utilise hydroponics to provide sustenance to their society. After being forced from their land via conflict, these people settled at Lake Tenochtitlan. They proceeded to build floating rafts topped with soil, allowing crops to grow through the tap layer and spread their roots into the waters below.

More recent, but still distant, examples of hydroponic growing involve the English scientist John Woodward in 1699. His work involved cultivating spearmint plants in water. He found that the plant species grew faster within a water source mixed with soil.

The history of hydroponics has shown how effective this method can be in many different settings and scenarios, with cannabis cultivation being no exception. Let’s explore the advantages of this interesting method, and how to apply it to growing great weed.

THE ADVANTAGES OF HYDROPONIC GROWING

If you talk to a grower who has experience with hydroponic growing, one of the first things they’ll probably tell you is that their hydroponic plants grow much, much faster than those in soil. This is a prime advantage of this method of cultivation—hydroponic plants usually grow 30–50% faster and often provide larger yields. A large reason for this is that nutrients within a hydroponic system are much more readily available to plants. The nutrients are suspended in water and enter directly into the root system as there is no soil to navigate through. In contrast, plants growing in soil must search through the medium in order to uptake nutrients from below. Easy access to nutrients allows plants to preserve energy, which is then diverted to growth efforts instead.

MATERIALS NEEDED TO MAKE A DIY HYDROPONIC SYSTEM

If you go the DIY route, check out the brief guide below. The list covers all of the equipment you need to construct a basic indoor setup. Simply find the product that suits you for each listed item. Buying your gear separately allows you to invest more heavily into important items such as lighting while reducing the cost in other areas.

Here’s what you’ll need:

a) Lighting (LED or HPS)

b) Lighting hangers

d) Hydroponic reservoir and tray

e) Airstone and pump

f) Growing medium (e.g. coco coir)

g) Net mesh planting pots

i) Ventilation fan and ducting tubes

j) Carbon filter

k) Oscillating fan

l) Hydroponic nutrients

m) pH and PPM meters

THE COST OF GROWING WITH HYDROPONICS

When thinking about hydroponics, you might picture a high-tech setup: automated switches, flashing lights, ticking timers. However, the cost of a hydroponic system all depends on how much money you’re willing to splash. They range from a simple plastic bucket all the way to self-draining and flooding systems. To save time, invest in a cheap hydroponic starter kit. These include all of the materials you need to get from seed to harvest. You can purchase one for around £200 (€235).

1. CHOOSE A GROWING MEDIUM TO GET THINGS STARTED

Now that we have covered the history and benefits of hydroponic growing, it’s time to get things started. To begin, you’ll need to select a growing medium—a substance that will hold in place the intersection of the stem and roots. From this location, the roots will grow down into the water in search of nutrients. The inert medium also allows good air access to the top of the roots. There is a huge list of different media used by cultivators, with those below being the most common. Each medium has its own unique benefits, and some work better with different systems. It’s all about experimentation when starting out to see which works best for you.

  • CLAY PEBBLES

As one of the most popular options, clay pebbles are excellent at aerating root systems. Clay pebbles sometimes require that growers alter the pH in order to provide an optimal growing environment, however, pre-altered pebbles can be purchased. You’ll need to place clay pebbles into a plastic hydroponic basket that has spaces for roots to grow through.

As one of the most popular options, clay pebbles are excellent at aerating root systems. Clay pebbles sometimes require that growers alter the pH in order to provide an optimal growing environment, however, pre-altered pebbles can be purchased. You’ll need to place clay pebbles into a plastic hydroponic basket that has spaces for roots to grow through.

  • ROCKWOOL

Rockwool is another popular choice, and is a substance created using volcanic rocks with a wool texture, hence the name. Rockwool has a tremendous capacity to retain water, which allows for good hydration of the upper root system. Rockwool can be placed within a hydroponic basket, but can also be lodged directly into the top of a bucket or tank lid without.

Rockwool is another popular choice, and is a substance created using volcanic rocks with a wool texture, hence the name. Rockwool has a tremendous capacity to retain water, which allows for good hydration of the upper root system. Rockwool can be placed within a hydroponic basket, but can also be lodged directly into the top of a bucket or tank lid without.

  • PERLITE

Perlite is a volcanic glass that expands when exposed to high temperatures. It’s often used in garden soils to provide aeration, which is exactly why it’s beneficial to use as a hydroponic growing medium for cannabis.

Perlite is a volcanic glass that expands when exposed to high temperatures. It’s often used in garden soils to provide aeration, which is exactly why it’s beneficial to use as a hydroponic growing medium for cannabis.

  • COCO COIR

Coco coir is a good sustainable option for a growing medium. As the fibre from coconuts, coco coir allows for good aeration and moisture retention. Coconut fibres are also known to protect roots from infection due to the presence of plant-stimulating hormones.

2. CHOOSE A HYDROPONIC GROWING SETUP FOR YOUR PLANTS TO THRIVE IN

Now that you’ve selected a growing medium, it’s time to choose which type of hydroponic setup to use. All systems are similar in that they utilise a nutrient-enriched water solution. However, setups can vary widely depending on factors such as water exposure and circulation. Most of the following systems can be purchased, but those with DIY skills could easily make them by using buckets, drills, pumps, and air stones.

DEEP WATER CULTURE

Deep water culture is a good place to start for beginners, and is likely the cheapest option. Plants are placed in buckets filled with a nutrient solution and an air pump provides a constant supply of oxygen.

EBB AND FLOW

An ebb and flow (also known as flood and drain) system features water that, well, ebbs and flows. These systems consist of several buckets suspended above a growing tray that features a water inlet and outlet. Both of these waterways are connected to an external tank that contains nutrients, an air stone to aerate the water supply, and a pump to move water into the growing tray. The roots in these systems are not continuously submerged within water. Instead, water periodically floods the growing tray with fresh oxygen and nutrient-enriched water. Once the pump cycle ends, all of the water drains back into the external tank.

This system allows for periodic feeding. The time when the growing tray is empty allows growers to easily tend to plant roots and harvest plants.

DRIP SYSTEM

A drip system in hydroponics is very similar to a drip irrigation system when growing in soil. This system consists of a large tray filled with growing medium, such as clay pebbles. Plants are placed directly into the medium, and each has its own drip pipe nearby. An external water tank with a pump and air stones constantly supplies a drip feed of water over each plant. The roots of these plants are constantly exposed to air, and the excess water drips down the medium and back into the external tank.

NUTRIENT FILM TECHNIQUE

If deep water culture is the equivalent of growing cannabis plants in a pond, then the nutrient film technique is the equivalent of growing weed over a river. This system involves placing plants into a tube that is angled, so water can enter at one side and exit at the other via gravity. The roots grow down into the tube, where they are exposed to the flowing water. The water enters from a tank with an air stone and pump, and returns back once the cycle is complete.

WICK SYSTEM

A wick system is a basic hydroponic setup that uses a growing tray similar to the drip system filled with clay pebbles. Under the tray is a tank of water, from which several wicks exit and enter the growing medium. Water travels up the wicks and passively hydrates the medium. No pump is required for this system.

AEROPONICS

Aeroponics is perhaps the most futuristic version of hydroponic growing, and uses misted water dispersed through the air to optimise aeration and hydration. Plants are placed into the top of a large tank of water filling the bottom 25%. Under the water is a pump that sends water into misters underneath the root systems. This fine mist constantly soaks the roots, allowing plants to receive massive quantities of air and water simultaneously.

3. PREPARE YOUR SYSTEM TO ENSURE A SUCCESSFUL GROW

After choosing your system, it’s important to prepare it well to prevent any detrimental situations. The damp and dark nature of water tanks is an ideal growing environment for a host of pathogens. Before running your system, you will need to sterilise your equipment to minimise the chances of contamination. Wipe down all of your buckets, trays, pipes, and tanks with rubbing alcohol, hot water, and peroxide. Once your system is sterilised, begin following the instructions to set it up correctly.

YOU’LL NEED TO MAINTAIN YOUR SYSTEM REGULARLY

Every hydroponic system requires frequent maintenance to provide an optimal growing environment. Below are all of the major factors you need to be aware of.

A) ALWAYS MONITOR PH

You’ll need to constantly test the pH of the water to ensure an optimal growing environment. Nutrients are more available to plants when the environment is slightly more acidic. Therefore, a pH of 5.5–5.8 is required. Use a pH testing kit to take regular readings, and be sure to change the solution weekly to maintain this range. During flowering, a pH of 6 is preferred.

B) TRY TO KEEP YOUR WATER TEMPERATURE AT AROUND 20°C

Hydroponic cannabis has an ideal temperature of 20°C. This factor can be monitored using a water thermometer and altered using a water heater if the temperatures are too low.

C) PROVIDE THE CORRECT QUANTITY OF NUTRIENTS

Hydroponic plants require the same nutrients as their soil-based counterparts. The easiest way to go about feeding your plants is by purchasing hydroponic nutrient solutions that contain all of the required substances for both the vegetation and blooming periods. Products will also describe how often to add nutrients back into your system and how much dilution is required.

D) KEEP THINGS CLEAN TO AVOID CONTAMINATION

Both growing trays and tanks require emptying and cleaning around every two weeks. This process will keep the roots of your plants safe against invading pathogens and diseases. Repeat the same process mentioned above when initially preparing your system.

E) SELECTING A STRAIN FOR HYDROPONIC GROWING

Strain selection is an important factor of hydroponic growing. Plants grown within these systems are free to uptake nutrients extremely fast, which often results in explosive and rapid growth. For this reason, selecting a large, towering sativa variety won’t be your best choice, especially if your system resides within an indoor grow tent.

Smaller and more compact strains are ideal for indoor hydroponic systems. Beginning with a smaller strain is advantageous for several reasons. For one, it will let you cultivate several plants within a smaller space, allowing for more diversity and potentially bigger yields. Additionally, if your plants do go through a growth spurt, you’ll have room to deal with such sudden surges in height.

Below are two strains that we recommend for hydroponic growing.

WHITE WIDOW

White Widow is a perfectly balanced hybrid strain that features 50% indica genetics and 50% sativa genetics. She was created using parent strain White Widow S1, and provides a well-balanced high that stimulates and excites the mind whilst relaxing and stoning the body. A THC level of 19% ensures a powerful psychoactive experience that lasts several hours. These flowers contain a terpene profile that emanates grounding tastes and smells of earth and pine.

White Widow will reach a height of 60–100cm when grown indoors, making her an ideal candidate for the spatial demands of a hydroponic growing operation. Expect good yields of 450–500g/m² after a flowering period of 8–9 weeks.

Hydroponics is a method of cultivating plants, specifically cannabis in this case, in a solution of water and nutrients.

Best Hydroponic Nutrients for Cannabis?

In other words, why are some hydro nutrients better than others for growing cannabis? What kind of hydroponic nutrients need to be avoided when growing marijuana? Do you need expensive nutrients to get good results, or will cheap nutrients get the job done?

With all the different bottles of marijuana nutrients out there, how do you know which one is best for your hydroponic setup?

When it comes to choosing hydroponic nutrients for growing weed, there are a few considerations that are really important!

Best Hydroponic Nutrients

  • Made specifically for hydroponics
  • No organic matter (nutrients are provided via minerals)
  • Mineral nutrients are “chelated” (easier for plant to absorb at a greater range of pH levels)
  • Contains rich sources of micro-nutrients (to make up for what might have been found in the soil)
  • Optimum NPK ratios (more info below)

Worst Hydroponic Nutrients

  • Made specifically for soil
  • Contains a lot of organic matter (guano, worm castings, fish emulsion, blood meal, etc) – this stuff can completely mess up your reservoir and cause unexpected and unwanted bacteria/root problems. If it seems cloudy with lots of material floating in the water, don’t use it for hydro!

You can learn a lot about nutrients by looking at the label!

Optimum NPK Ratios for Hydroponic Cannabis Nutrients

N-P-K stands for Nitrogen-Phosphorus-Potassium, which are the three most important plant nutrients. These are what the 3 numbers listed on the front of all nutrient bottles stand for (Potassium is represented by “K” because chemists use the symbol K in the periodic table for potassium).

In order to get the best results growing cannabis in hydroponics, it’s important to give the right ratio of these crucial nutrients so the plant gets what it needs at the right time. For example, if you give too much Nitrogen in the flowering/budding phase, it actually surpresses bud production and reduces your yields even if the plant is completely healthy! You don’t want that!

So what are the optimum NPK values for growing cannabis in hydro?
(N-P-K are the 3 numbers on the front of nutrient bottles)

Optimal Hydroponic Cannabis N-P-K Nutrient Ratios
Life Stage N P K
Vegetative/Grow High Medium to High High
Flowering/Bloom Low High High

Additionally, hydroponic nutrients should always include….

  • Magnesium
  • Calcium
  • Iron
  • Sulfur

Nice but not necessary micro-nutrients (contained in most water sources, but if using RO or very soft water you want these in your nutrients to prevent possible deficiencies)

  • Boron
  • Cobalt
  • Copper
  • Manganese
  • Molybdenum
  • Zinc

The main difference between NPK ratios for hydro and soil are….

  • Hydro nutrients usually contain more micro-nutrients (in trace amounts), to make up for what the plant would have been able to find in the soil
  • Hydro nutrients tend to contain higher levels of Nitrogen, which is abundant in soil but not in most water sources.
  • Hydro nutrients tend to have lower levels of Phosphorus, because Phosphorus is more “available” to the plant in a hydroponic setting. In soil, there are microorganisms (as well as clay “colloidal” particles) which can ‘steal’ some of it, and soil nutrients compensate by adding more Phosphorus.
  • Hydro nutrients rarely use organic sources of nutrients. Soil nutrients often contain organic material, which can can make it easier for bad stuff to grow in a hydroponic reservoir. Organic sources of minerals also usually need to be broken down by microorganisms before the plant can absorb them, which doesn’t happen as well in a soilless environment.
  • Hydro nutrients are often made up of chelated minerals which have been specially treated so they are easier for the plant to absorb.

What are Chelated Nutrients? Manufacturers actually “wrap” the nutrients inside an organic molecule that is less affected by pH, making it easier for the plant to absorb even if the pH is too high or too low.

When set up right with good nutrients, DWC / Hydroponics can produce some incredible yields!

Optimum pH of 5.5-6.5 Recommended DWC Nutrients & Supplements

These hydroponic nutrients systems are not just great as far as cannabis yields and quality, they won’t break the bank either! There are lots of great nutrient systems out there, but the truth is that you don’t need incredibly expensive nutrients to get incredible marijuana!

The following nutrient systems have proven to thousands of growers, big and small, that they have everything needed to produce star-quality cannabis!

General Hydroponics Flora Trio Lineup

These plants grown using just the GH Trio + Hydroguard (formally known as Aquashield)
Feel free to check out the complete grow journal (over 1 lb harvest!)

General Hydroponics Flora Duo Lineup

General Hydroponics FloraDuo (Bottle A & Bottle B) ​

Hydroguard (formally known as Aquashield) – prevents and treats root rot.

House & Garden DWC Kit Lineup

Warning: H&G Products have been difficult to find online lately

The House & Garden line-up is expensive yet remarkably effective. Aqua Flakes A + B, Roots Excelurator, Algen Extract ​

Hydroguard (formally known as Aquashield) – prevents and treats root rot. No need for extra Cal-Mag with the Aqua Flakes line as it already comes with plenty!

Botanicare KIND Hydro Lineup

This is actually the hydroponic nutrient lineup I plan to use for my next grow. Right now I’m using the General Hydroponics Flora trio (which I’ve used for more than half a decade with amazing results), but I’ve decided I want to try something new and KIND is what I’ve decided to go with. I’ve heard/seen so many great things about it and Botanicare is a great company that takes feedback from cannabis growers and is happy to answer any questions if you contact them through their website.

Botanicare KIND Trio For Hydro (Base, Grow, Bloom) ​

From a grower who wrote in: “I use the Botanicare KIND lineup – it seems to get good results, not too expensive, and works very well in hydro.” Another grower told us, “As far as favorites go, I’ve been pretty pleased with Botanicare KIND, it’s ‘pretty good’ when you follow the chart, but once you start tinkering with it based on what you see with your plants, it’ll really shine since it was developed to be played with.” Apparently a lot of growers like tinkering with this trio as another grower said, “Botanicare KIND is like the opposite spectrum [of the Botanicare Pure Blend series]. The Base is just Nitrogen and Calcium. Grow and Bloom both have most of the minerals in them, along with things like seakelp! The Bloom is also 0-6-6. Grow at 2-2-4. So quite literally you can call the shots on Nitrogen and Calcium. That level of control hasn’t been around a great deal in our market. For the savvy grower this is a pretty nice tool.”

If you think you have the best hydroponic cannabis nutrients, tell us about your results!

Ever wondered what makes hydroponic nutrients "good" or "bad" for cannabis? Learn about the different types of ingredients that go into hydroponic nutrients to learn which ones work great for marijuana, and which ones to avoid!