If it’s possible to over-water a plant, then how is it that plants can sit in the water while in a hydroponic system? Plants need air exposed to their roots or they will suffocate. In nature, drying dirt allows air to reach the plant’s root system. In hydroponics, you have to expose the root system to air by other means. Here I’ll give you 5 ways to expose your hydroponic plant’s root system to oxygen.
Why Do The Plants Roots Need Oxygen?
As many of you know, plants release oxygen during the process of photosynthesis. That doesn’t mean plants don’t need oxygen. What you might not know is just like we breathe oxygen, so do plants. Humans have a circulatory system that carries oxygen throughout the body, but plants don’t have a circulatory system that distributes the oxygen as we do. This means that plants must take in oxygen at both the top (the leaves) and bottom (the roots) of the plant.
Ways To Provide Oxygen To a Hydroponic Plant’s Root System
Use An Air Stone
The most common way for hydroponic gardeners to oxygenate the water in their hydroponic system is by using an air stone. The reasoning is that air stones are inexpensive and easy for hobby hydroponic gardeners to find.
The air stone is connected to an air pump that pushes the air through the stone. The air stone is porous, splitting the air into a bunch of large bubbles. The bubbles that an air stone creates are typically large so while they get the job done, air stones are not the most efficient.
Air stones come in many different shapes and sizes making it easy to find one to perfectly fit your hydroponic system. They tend to be pretty breakable, so when purchasing an air stone I recommend spending a little extra to get one that has some plastic reinforcement. I prefer the discs, especially when growing plants with large root systems, as the discs spread out the bubbles reaching more of the root.
Use An Air Diffuser Tube & Ring
Another common way of oxygenating the water of a hydroponic system is by using an air diffuser. Air diffusers are typically made of a bendable tube with holes in it, releasing air into the water. Air stones typically have more evenly distributed holes throughout the tube which evenly distributes the airflow.
The biggest advantage air diffusers had over air stones was the size of the bubbles. The large bubbles created by the air stone rise quickly often not touching much of a large root system. The holes in air diffusers produce smaller bubbles causing them to stay in the water for a longer period, exposing more oxygen to the root system to ensure maximum oxygenation. With the growing interest in hydroponics, there are now many air stones on the market that produce smaller bubbles.
Set up An Automatic Siphon
Popular in ebb and flow and aquaponic systems, siphons are a great way to automatically drain a hydroponic grow bed. When the grow bed drains it exposes the root system to air, providing oxygen to the plant’s root hairs.
There are several different types of hydroponic automatic siphons including the bell, loop, and u siphons, but they all work on the same principle. As the water level in the grow bed rises, it reaches a certain point where the water starts going down a tube (a standpipe) back into the grow bed. When the standpipe gets to a point it completely fills with water, the suction creates a vacuum that sucks the water quickly out of the grow bed.
When water is sucked into the pipe it breaks the suction, allowing the grow bed to fill, and the process repeats.
Let The Roots Hang
A hydroponic plant doesn’t have to sit in the nutrient water. Some plants are instead suspended in the air and nutrient solution is splashed over the roots. Many vertical hydroponic systems and also aeroponic systems use this method of growing.
In most vertical systems, the nutrient solution is pumped to the top of the system, then falls back to the reservoir dripping on all of the different plant’s roots on the way down. With aeroponic systems, the nutrient solution is instead sprayed up at the plant’s roots.
Give An Oxygen Gap
In some hydroponic systems, like NFT or the Kratky Method, the plants received oxygen through an air gap in the system.
When your plant has a healthy root system, as long as the bottom of the roots are touching the nutrient solution the plant will be able to take it in. The air gap between the base of the plant and the nutrient solution is oxygen for the plant to breathe.