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Hey everyone, and welcome to the Cannabis Horticulture Series. Today we’ll be going over a general overview of hydroponics so you can know this, too.
While the word hydroponics might bring to mind large rows of plants in a clean room, complex setups utilizing pumps and gravity, and a lot of roots dangling in the breeze, the actuality of hydroponics just means growing plants without the use of soil. And because the term is so broad ranging, something like this, which looks exactly like a normal soil grow, except with coco coir instead of soil, is considered a hydroponic setup.
And same with something like this, which clearly doesn’t look like soil.
Same with this, this, this, and this.
And while the different systems vary greatly in how they work, all of them have one thing in common, which is to provide a favorable environment for the roots of a plant to thrive after taking away the protection and benefits that soil traditionally provides. So while above ground, everything is still the same as a soiled grow. Below, without the use of a soil that typically provides things such as stability, micro nutrients, temperature control, and a pH buffer, all of these will need to be adjusted manually, although when done correctly can significantly increase a plant’s growth rate because everything now can be fully optimized.
Best Water Temperature for Hydroponic Plants?
So what does a favorable root zone environment look like? Let’s take a look first at the temperature. Unlike leaves above ground, which have some systems in place to handle some environmental changes and temperature spikes, roots are not able to protect themselves from the high and low temperatures of a typical day to night cycle and definitely can’t handle spikes of their temperature.
So optimally room temperature, or around 70 degrees, is ideal for healthy roots, with a maximum fluctuation of plus or minus 10 degrees, which will need to be consistently maintained to optimize root development.
Plants Need Water, Nutrients, & Oxygen
Now that the temperature is correct, roots need a constant supply of three things. Water, nutrients and oxygen. Water and nutrients go hand in hand because nutrients are taken in along with water. So let’s take a look at both of them together.
Plant Nutrients & Water
The nutrients you’ll need to provide in a hydroponic setup will need to be included in the water for the plants uptake. And without the micronutrients typically already provided from soil, these will need to be added in as well, which is why you can’t use off the shelf soil nutrients for hydroponics, as these typically only include the primary nutrients of nitrogen, phosphorus, and potassium, but are usually missing the secondary macronutrients of calcium, magnesium, and sulfur, and all of the micronutrients of iron, magnesium, boron, copper, zinc, cobalt, and so on.
There are also organic ways to feed the plant as well, with a popular trend of including fish to the system so that the fish waste, after being broken down by beneficial bacteria, provides the nutrients the plants need, and in turn by removing the waste from the water, cleans the water for the fish to thrive in.
Recommended Water PH Levels
As for the water part of the equation, without the benefits of soil providing a pH buffer, hydroponic systems will require a very specific pH range of water for the nutrients to be available to the plants, which is between a 5.5 to 6.5. So pH testing and balancing the reservoir water, or for every watering, will be necessary.
Finally, we have oxygen. And this is the simplest yet most complex part of the equation, as oxygen is readily available, except in water. So when looking at all the different types of hydroponic setups, each of them provide their own solution for how to get both water and oxygen to the roots. You can submerge the roots in water and then oxygenate the water with a waterstone. You can provide both a wet and dry environment back to back with an ebb and flow or drip system. Or you can keep the roots in the air and mist them with water with necessary with an aeroponics system.
What hydroponic lax in simplicity, it makes up for with versatility, and that floods over to the different type of hydroponic grow mediums available as well. And while it’s possible to let the roots grow suspended in the air or submerged in water, soilless grow mediums are a great tool for many hydroponic setups, as they provide some of the benefits that traditional soil would provide, but in a hydroponic setting. From plant stability, to temperature control, to water retention, each soilless grow medium has their pros and cons. And with a wide variety of options to choose from, it’s easy to select one that fits your grow situation if needed, and you can always utilize a mixture of different soilless grow mediums to maximize their potential while minimizing their drawbacks.
Common Hydroponic Setups
So now that we’ve covered the basics, let’s go over some of the most common hydroponic setups to understand how each are able to tackle the air and water dilemma. First, we have a basic system which is growing a plant utilizing a soilless grow medium and watering by hand. This is as similar to a soil grow as it gets. With the complexity coming from having to use a hydroponic nutrients system, pH balancing of water, and understanding the pros and cons of the grow medium used to not over or underwater the plant. And just like soil grows, water is provided to the roots when watered, and air is provided to the roots when the grow medium dries.
Next we have the passive system. One popular option is utilizing a wick to passively bring water from a reservoir to the grow medium, which keeps the grow medium not too dry and not too wet, just damp enough to provide both air and water to the roots.
Another even simpler system takes advantage of how roots developed, by keeping the plant in a container of nutrient rich water. As the first roots drink the water, the water level drops, which then leaves a growing pocket of air for the new roots to breath, as the oldest roots continue growing, drinking water from the lowering of water level.
Deep Water Culture
Now we have the completely submerged system of deep water culture. And this system grows the plant in the water, and then oxygenates the water through in airstone or by creating a waterfall like effect. Simple, easy to set up and effective. For the systems that provide both air and water to the roots at different intervals, two common methods are a drip system and an ebb and flow system. A drip system is exactly as it sounds, providing a slow flow of water from the top of the plant and utilizes gravity for the water to flow down to the bottom of the roots. And when done in intervals, the roots have time to take an air in between the water cycles.
Ebb and Flow System
An ebb and flow system does the exact opposite of a drip system by providing water from the bottom up, and flooding the root system before draining it out again. This method provides a much more even watering to all the roots, and never exposes the water above ground to prevent algae issues.
Now for aeroponics. This is the inverse of a deep water culture system. So instead of submerging the roots in water, we keep the roots suspended in the air. And instead of having a provide air through an airstone, we provide water with a spray or mist.
So as you can see with hydroponic setups, you’ll need the correct tools, fertilizers, grow medium, and set up, which could vary greatly in complexity, scalability, and automation, making deciding on a good hydroponic setup for your gross space a tough choice. So be sure to join us for the next batch of Cannabis Horticulture Series videos, as we’ll be breaking down each piece of a hydroponic grow and set up in much more details. And that’s it.
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