Roots Won’t Grow in DWC Hydroponics? This is Why

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Hydroponics is one of the best ways to grow plants at home. But it isn’t always as simple as it seems. Quite a lot can go wrong with the system! And none more so than in Deep Water Culture (DWC) hydroponics. A common problem is stunted root growth. If you’ve been trying to grow plants via DWC but have noticed that the root system isn’t growing well, there could be a number of reasons.

The majority of the reasons why your plant’s roots aren’t growing in your DWC hydroponics set-up are directly linked to the condition of the nutrient solution. Common issues, such as pH imbalances, temperature fluctuations, over-oxygenation and contamination can prevent nutrient absorption and be a leading cause of root rot, which can prevent root growth.

Fortunately, most issues can easily be prevented with the proper care and attention. In this blog post, we’ll address the most common causes of why the root system of your plants may not be growing as it should, and what you can do to get them back on track. Let’s get into it.

6 reasons your plant’s roots aren’t growing in your DWC hydroponics system

1. Insufficient nutrient levels

One of the most important things to ensure in DWC hydroponics is sustaining the correct level of nutrients for your plants. Without a balanced supply, plants will not be able to absorb enough of what they need to grow and their roots will not be able to develop.


Don’t underestimate the importance of nutrients and consider carefully the levels and type of nutrients needed for your plants. Make sure to use nutrient products that work well with DWC hydroponics. Some good examples are FloraBoom by General Hydroponics and General Hydroponics FloraGro 2-1-6 or even Botanicare CNS17.

2. Too much oxygen

Oxygen is a vital element that supports the growth of your plants. However, conversely, too much oxygen can actually inhibit root growth in a phenomenon known as ‘root stunting’. When the nutrient solution is too rich in oxygen, roots are discouraged to grow further since their oxygen needs are already met. This can also stunt the growth of the whole plant.


Reducing the amount of airflow into the nutrient solution can help to encourage root growth, but getting the balance right is tricky and important. Frequently moving the positions of any air stones can also help prevent roots positioned directly above them from beginning too saturated with oxygen.

3. Temperate extremes or fluctuations

Extremes in temperature, whether it be too cold or too hot, can also have a negative effect on root growth. Additionally, frequent temperature fluctuations can further inhibit root growth and impact the health of your plants.


Make sure you research the optimal temperature for your nutrient solution depending on the type of plant(s) you are growing. For most plants, this will be between 65°F and 80°F (15.5°C to 29.5°C). The nutrient solution should be kept at a consistent temperature to ensure proper root growth.

4. pH imbalances

pH balance is often overlooked but can be one of the most important factors influencing root growth in hydroponics. In essence, pH affects how your plants take up nutrients. Therefore, maintaining the right levels is crucial. Too high or too alkaline, and your plant will not be able to absorb the nutrients it needs which can lead to deficiencies and stunted growth, including root growth.

Testing the pH of your nutrient solution is critical


Maintaining a pH range of between 5.5-6.5 is generally considered optimal for hydroponics. To help you achieve this, I’d recommend buying a pH Monitor that can help you keep track of the current pH levels and make necessary adjustments.

5. Contaminated water

Contaminated water can also be a factor affecting root growth. Contaminants like certain bacteria, fungi and algae can all cause issues if left to build up in the system over time. These build-ups can compete for resources within the system and prevent roots from effectively absorbing nutrients if left unchecked.


Although it’s a chore, it’s important to regularly clean and sanitize your hydroponics system in order to prevent and remove algae and the build-up of any other nasty contaminants.

6. Your plants have root rot

Another important thing to look out for is root rot which can be very damaging to a plant’s roots and prevent their growth. Root rot is largely caused by a fungus – Phytophthora – that thrives in damp, hypoxic (oxygen-poor) environments. The fungus attaches itself to the root system, preventing it from absorbing nutrients and eventually killing them and the plant altogether. If your plant is yellow, wilted or brown, chances are it suffers from root rot.

Watch this informative video about root rot to help you identify it and prevent it:


Prune any dead or dying roots. Ensuring your plants receive the right amount of air to keep the roots well-oxygenated is key and can be achieved by using an air pump completed with air stones. Regularly clean your hydroponics system to remove contaminants that may lead to disease. In addition, regularly pruning the roots that become too large can help to prevent root rot.

7. Too much light

Too much light reaching the roots can cause issues that led to stunted growth, root rot or even death. Light is a leading cause of algae and fungus growth. By allowing too much light to reach the root system, it can cause a build-up of unwanted contaminants that prevent roots from absorbing nutrients.


As far as possible, prevent light from reaching the root mass. This will limit the build-up of contaminants that will choke the roots over time.

What do healthy roots look like in hydroponics?

Healthy roots in hydroponics should appear tan or white in colour and are generally healthy looking. They should be free from discolouration and there should be no evidence of rot, stickiness or bad smell. The root should be firm and not disintegrated. Healthy roots should also have a good amount of branching and be firmly attached to the growing medium.

A healthy root system for plants growing in a DWC hydroponics system

How long should a plant’s roots be in DWC hydroponics?

The length of roots in your DWC hydroponics system will depend on the type of plant you are growing. Rather than root length, however, it’s more important to keep an eye out for root health. If the roots look visibly unhealthy (discoloured, rotted, smelling etc.) then they should be pruned immediately.

Should you trim the roots in your DWC hydroponics system?

In some cases, the root system can become so large in DWC hydroponics that it starts to impede the proper functioning of your system, which in itself can have a detrimental impact on the health of your plants. In such cases, it’s recommended to prune the roots back to create more space.

It’s recommended to wait until a plant is well-established before pruning. Periodically prune the most obstructive roots, but never prune more than 10-15% of the total root mass as a general rule. If you trim too much, you could damage the roots and prevent them from growing back.

Closing thoughts

There are several things that can negatively impact the growth of your plant’s root system in hydroponics. The good news is, with proper care and attention, most of them are easily preventable or treatable if spotted early enough. Hydroponics, like most gardening, requires time and attention to detail. The more effort you put into looking after your plants be healthier and more productive they will be.

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William, an experienced consultant and passionate advocate for technology and sustainability, is the founder of Smarter Home Gardens. William's journey into gardening began with the purchase of his first home, which came with a small backyard garden. Despite initial challenges brought about by limited space, soil, and sunlight, William's determination to create a vibrant garden led him to research and experiment with innovative gardening technologies and sustainable practices. Driven by his lifelong enthusiasm for technology and sustainability, William explored various gardening methods, including vertical gardening, hydroponics, companion gardening, and composting. Through these efforts, he realized that it was possible to combine his passions with his newfound love for gardening. Smarter Home Gardens was born out of William's desire to share his research and experiences with others, helping them create smarter gardens that leverage cutting-edge technology and contribute to a more nature-positive world. The blog offers in-depth articles on innovative gardening technologies and methods, helpful 'how-to' guides, reviews of the latest gardening technology, and research on cost-effective garden maintenance solutions. William's commitment to sustainable and technologically-driven gardening has made him a trusted voice in the field. His enthusiasm for creating gardens that work with the planet, rather than against it, is evident in every post he shares on Smarter Home Gardens. Through the blog, William hopes to engage with a wider audience, encouraging others to join him on this exciting journey towards smarter, more sustainable gardens.

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