Root rot fixed in hydroponic basil

Fixing Root Rot in Hydroponic Basil

Root rot is the sneakiest plant disease, but not for hydroponic basil.

They usually go unnoticed because basils grown in solid don’t show symptoms until the root is rotten to a reasonable extent. The leaves may turn yellow, which is often mistaken for nutrient deficiency or some mildew attack. Then, the plant growth will be stunned. Again, there are a bunch of reasons for stunted growth. Removing some roots and inspecting yourself is the only way to ensure it’s a root rot. Rotten roots are black and smell bad.

Luckily, hydroponic growers don’t have all these problems. When you see yellow leaves or stunted growth in a plant, you can inspect its roots and remove it from the system. Once you are done inspecting, you can place the plant back on the system without damaging the roots or any other part.

This post discusses the causes, diagnosis, and fixes for root rots in hydroponically grown basil plants. Yet, most of these points are also valid for many other crops in hydroponics.

Causes of Root Rot in Hydroponic Basil

Fungi, bacteria, and poor water management usually cause root rot in hydroponic basil:

  1. Fungal Infections are the most common cause of root rot in hydroponic systems. Fungi like Pythium, Phytophthora, Rhizoctonia, Fusarium, and Phoma attack basil roots and create root rot. This leads to symptoms like wilting, yellowing leaves, slow growth, and roots that turn soft, brown, or black.
  2. Bacterial Infections can also cause root rot, especially in consistently damp conditions. Bacteria such as Erwinia, Pseudomonas, Rhizomonas, and Xanthomonas create wet, soft root rots.
  3. Poor water circulation and oxygenation can contribute to root rot. Stagnant or poorly oxygenated water provides an ideal fungal and bacterial growth environment.

How to find root rots?

As mentioned, root rots are easier to find in hydroponics than in soil-based farming. Although this is beneficial in industrial-scale farms, monitoring is still a challenge.

Since the conditions in the hydroponic system cause root rot, a few nearby plants would show the symptoms together instead of one among many.

The earliest sign of root rot is stunned growth. Rotten roots slow the plant’s growth because they can’t absorb nutrients. Then, the leaves may turn yellow, indicating that the leaf doesn’t get enough nitrogen. Eventually, these plants may die.

If any section of your farm doesn’t grow as well as the others, you must inspect that area. Remove a few plants from the system and inspect their roots. Entirely rotten roots are usually black. You’re lucky if you can pick them up when they are brownish. At this level, root rot is easily fixable.

Rotten roots also smell bad. Yet, the smell is hard to spot in the early stages of root rot. Especially in hydroponic systems, the smell disappears in the water.

How to prevent root rots

The traditional advice on preventing root rot is to use a growing medium with good draining capacity and alter the watering schedule. Both these would reduce the water retained near the roots. When there’s air near the roots, the roots can breathe oxygen, preventing root rotting.

Yet, in hydroponics, altering the watering scheduler is not an option since the plant is grown directly in the water. The preferred way is to aerate the water or introduce recirculation.

Dr. Kratky has found that a gap between the plant’s base and the nutrient solution encourages air-breathing roots. Thus, the bottom part of the root absorbs nutrients, and the top part keeps breathing oxygen. This, too, can prevent root rot. Kratky’s hydroponic method is excellent for growing basil and many other plants.

Yet, Kratky systems used outdoors need to be continuously monitored. When there’s a storm, water builds up in the container, disconnecting the breathing roots from the air.

Thus, installing an air pump and air stone would ensure a continuous oxygen supply to the roots through the water.

Instead of aerating like this, you may switch to a recirculating system. Hydroponic systems like NFT, Flood and Drain, and Dutch buckets recirculate the nutrient solution. Moving water has more oxygen to prevent root rot than stagnant water.

How to fix rotten roots.

Dead roots are gone forever. Yet, you can control the growth of rotting. The plant will grow new, young roots by itself.

The first thing to do is increase the water’s oxygen content. As mentioned, you can aerate the water or try a circulating hydroponic system. If you still see root rots in systems like NFT, you may have to reduce the depth of the film. Just a little moist would do.

Secondly, you can treat the root rot with hydrogen peroxide. Mix one part of 3% hydrogen peroxide with two parts water in a watering can or spray bottle. Remove the plant with rotten roots and cut off as many as possible. Finally, spray the mix directly to the remaining root. You can then place the plant back into the system.

Hydrogen peroxide is a safe chemical to use in most gardening activities. It’s simply water with one more oxygen in every molecule. In the presence of light, they become water again. Yet, it is strong enough to eradicate most germs and fungi.

Although some plants are severely affected by root rot, basil is an exception. Even without treatment, basil can recover and grow new roots if oxygenated water is present. Since basil stems can grow roots, they can regrow well even if many are damaged.


Root rotting is one of the leading causes of plants dying in hydroponic systems. It’s prevalent in non-circulating systems like Kratky. Thankfully, basil can turn around from rotten roots. Simply increasing the oxygen content with an air pump would do.

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