Is Chemical Flushing Necessary?

By Rich Hamilton
Published: February 12, 2017 | Last updated: April 27, 2021 12:54:27
Key Takeaways

In nature, water serves as an ideal flushing system. It will work for your hydroponic system, too. But is it the best means available? Rich Hamilton dives in headfirst to determine if flushing your plants with chemicals is worth it.

It is heavily debated that using a flushing agent to help clean your plants of any unwanted chemicals is a pointless exercise, and that using water can be just as effective. There tends to be strong, differing opinions on this topic, depending on who you talk to. In an effort to settle the matter, let’s look at what flushing agents do to help determine if they hold an advantage over water.


Starting with the basics, most people that grow hydroponically want to produce the biggest and best crops possible in the shortest amount of time. To do this, there is normally a chemical-rich nutrient feeding solution used to support and feed the rapid growth of hydroponic plants. While these nutrients are a vital part of producing such crops, they can often leave unwanted chemical traces within the plants. These traces can manifest themselves in the plant as a chemical-like taste, smell, or color. To remove these unwanted effects, most hydroponic growers, whether hobbyists or commercial, will flush their plants. This flush is intended to clean the plant of the unwanted chemicals that may still be stored within the plants.

First, A Little Biology

Most fruit- or yield-producing plants have a vascular system. The vascular system of the plant is what takes the nutrients and water around the plants via the roots (considered the start of the vascular system) and feeds the entire plant, including the leaves, to fuel the photosynthesis process. This, in turn, helps the fruits to develop along with the overall growth of the plant. The vascular system also transports starches, sugars, and nutrients absorbed by the plant around the whole structure, including the fruits.


As the plant’s vascular system transports these vital sugar and nutrients around the plant, helping it to grow strong and healthy, it deposits the reserves it doesn’t need in certain parts of the plant. The main reserves are held within the stem and root ball. In a normal plant under normal conditions, these deposits are made up of natural, low-level chemical elements that are released when the plant needs them over the different stages of its lifecycle. In hydroponics, a controlled environment means there is an abundance of nutrients and chemicals being fed to the plant, so the buildup of these chemicals that are naturally stored in the plants tissues is not needed. It is vital to remove these chemicals before harvest. Not flushing the plants of these chemicals can leave your harvest unfit for human consumption.

Within a plant’s vascular system are two main paths. The first path is the xylem, which is composed of four different cell structures. It is this path that transports water and dissolved nutrients from the roots throughout the plant and its organs. It also stores substances such as dissolved nutrients and water for later use. An easy way to remember it is to note that the xylem transports liquid for the plant to drink.

The second path is called the phloem. The phloem is made from four different types of cell structures that transport the sugars made in the leaves throughout the plant and its organs. The plant can turn any of these unused sugars into starch and store them for later use. An easy way to remember this is to note that the phloem transports food for the plant to eat.


The Flush Factor

The first part of the flush process is to stop any further intake of nutrient elements via what the plant is drinking, through the xylem, and replace it with plain water. The second part is to flush out as many active chemical elements as possible that are already present in the plant’s vascular system. This is where the term ‘flushing’ comes from. The faster the plant is flushed of all active chemical elements, the faster it can move on to the next stage of the process. This is the key to the process.

Water performs this process naturally in the wild over a much longer period of time. Hydroponics differs greatly as it uses constructed systems to get the most out of the plant in the shortest amount of time possible and to the best of its potential. So yes, while water works for this part of the process to a certain degree, a flushing agent will work faster. How? Well, it’s designed that way.


While the whole process is complicated, the principle is simple. Think of water as a shape. For argument’s sake, let’s say water is an L shape. When this shape (the water molecule) is sent around the vascular system, it dilutes the active elements by picking off the chemical molecules. While the shape of the water molecule may seem ideal at first glance, it is not the best or the most effective shape.

In comparison, let’s say that the flushing agent’s shape is an X. As you can see, this shape will be more effective. It’s basically four Ls back-to-back, so therefore should be four times as effective as the L shape. As this molecule moves around the plant’s vascular system, it will attract more chemical molecules than the L, thus diluting and flushing the active chemical elements out of the plant faster. As soon as the vascular system is not providing the plant with the nutrients it needs, it will start to release and use up the reserves it has stored previously. This is the next stage of the flushing process. Getting the plant to use its reserves faster will not only clean the plant of unwanted chemicals faster, it will also mature the produce faster.

And the Winner Is …

So, does just water work? Yes, it will flush your plants. Does using a flushing agent work? Yes, it also works, but much better. It will flush your plants faster than plain water and help them mature faster.

For the people that don’t believe in using flushing agents, I ask this: Would your plants grow if you just simply used water throughout the entirety of their life? Yes, they would. Would they produce as high a yield? Would they be as big, or as developed, if you used a tailor-made range of nutrients? No. Not a chance.

I believe that using a flushing agent is a vital part of a hydroponic feeding schedule and that the people who don’t use one are missing out on better results from their plants.

In conclusion, if you have never tried a flushing agent, maybe this is the time to give it a chance.


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Written by Rich Hamilton | Writer, Consultant, Author of The Growers Guide

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Rich Hamilton has been in the hydroponics industry for more than 20 years, working originally as a general manager in a hydroponics retail outlet before becoming an account manager at Century Growsystems. He enjoys working on a daily basis with shop owners, manufacturers, distributors, and end users to develop premium products.

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