How Hydroponics Works

The core idea of hydroponics is taking plants from their natural environment (outside in soil) and putting them in a environment where you have greater control of all the variables of growing. What you’ll find in learning about how hydroponics works is that hydroponics is all about control and precision.

What Soil Provides for Plants

How Hydroponics Works by Replacing SoilMost hydroponics systems give up entirely on soil, opting for better options. Learning about how hydroponics works can be done by looking at what soil provides and what it is replaced with in hydroponics.


the most obvious thing that soil provides is nutrients to the plants. While photosynthesis uses water and CO2 alone to make sugars for the plant, the plant requires other nutrients to grow and perform other functions. These include nitrogen, potassium, phosphorus and to a lesser extent other elements like sulfur or zinc. Soil provides these nutrients because soil contains bacteria and fungi that take large biomass (say a dead tree) and decompose it, leaving nutrients behind in the soil.

How Hydroponics Plants Get Their Nutrients

As mentioned earlier, hydroponics is about control. Using fertilizer, you can control the nutrients in your soil to some degree. However, if you have plants in a hydroponics system, you can give them precise quantities of nutrients and you or an automated system can check these nutrients daily, if you want to. This level of precision, this control, is one of the advantages of hydroponics and is a key part of how hydroponics works. You can get a better yield, a better harvest because you can control the nutrients to a greater degree. (Note for beginners: while you can check nutrients on a daily basis, it’s not required.)


Stability is a property of soil that’s easily overlooked until you wonder how you’re going to get a plant to stand up on its own. Most hydroponics system will use one media or another to act as a source material for the roots to grow through/around and which will provide the plant with stability. In nature, this is easily achieved by the soil with all of its small rocks other components

How Hydroponics Plants Get Their Stability

Hydroponics systems generally use two things for stability- the first is something for a seed to sprout in and put down initial roots. Hydroponics systems commonly use a material called rock wool, which essentially feels like a compact fiber-glass like material. Rock wool is not bio-reactive and it holds water well, making it a great initial environment for seedlings. Second, as plants get bigger, often times they are transplanted into a new stability media (also called a substrate). Many people use clay pebbles, taking the small rock wool that a plant is in and placing it inside a net cup surrounded with clay pebbles. As the plant grows, it’s roots will go through the rock wall, wrap around and down the pebbles in search for water.


This one is an obvious one. While water comes in the form of rain or from a river, soil can help soak up and keep water close to plants. Water is necessary for photosynthesis to occur. It’s also necessary for the plants to remain stiff and vital, a concept known as tugor pressure, that allows plants to stand upright even without any kind of skeletal structure.

How Hydroponics Plants Get Water

Water delivery is the crux of any hydroponics system and it’s often what sets apart one system form another. Some systems drip water above plants, allowing the roots to collect the water as the water flows down the clay pebbles. Other systems have a reservoir of water below where the plants’ roots will grow down and be submerged. Yet other systems will use periodically flood plants roots. If you need help choosing which system is right, check out our page on choosing the best hydroponics system for beginners.

Now that soil is out of the way, hydroponics practitioners can deliver precise amounts of nutrients, water, and air to plants all while tightly controlling their environment from temperature to humidity, CO2 levels, and even light exposure. This allows us to take the reigns instead of allowing mother nature to drive.

Now that you’ve got an idea on how hydroponics works, we’re ready to dive into a few topics with a bit more depth. Next up is a crash course on nutrients.

Next Section: A Beginner’s Guide to Hydroponic Nutrients

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