Easy Ways to Prevent Root Rot in Hydroponics

September 18, 2020October 18, 2020 by Joshua

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I wondered what causes root rot in hydroponics as my plants stopped growing, drooped, and eventually shriveled up.“Why are my hydroponic plants dying?”

I thought it was over nutrients, too much light, or bad seeds. The problem, however, was much more sinister.

Even though hydroponic growing is simple, several things can go awry if you are unaware of common problems that come with hydroponics.

Today we will focus on what root rot is, how it affects your plant, and how to detect and prevent it.

Table of Contents

What Does Root Rot Look Like in Hydroponics?

If your plants look like this, there may be a problem.

The most common sign of root rot is brown, soft, and slimy roots.

Root rot will prevent growth with your roots as well, so you may notice a small number of roots in comparison to the whole plant.

Healthy roots are white firm and strong in comparison. It should look full, dense, and have many branches.

Up top, your plant will have stunted growth, wilted or discolored leaves.

This lettuce I have here is over 2 months old and should be ready for harvesting. An adult lettuce plant should be 10 times as big as these plants.

Have a look at the roots below also. The plant should have hundreds of long white roots.

2 Common Causes of Root Rot in Hydroponics

Lack of Oxygen

Roots need 3 things to survive. Water, oxygen, and nutrients.

Your plants can easily drown in the nutrient solution if you are not careful in a hydroponic system. Most hydroponic growers use growing mediums to place plants in to prevent completely submerging the plant.

If you grow with the Kratky Method, you need to ensure there is a pocket of air in your container to allow some roots to be out of the water to breathe.

With plotted plants, over-watering will quickly lead to the doom of your plant. Many people do this and are often the number one reason for the potted plant’s demise.

Indoor plants do not need water often, so stay away from that watering bucket!

Plant Pathogens and Diseases

Fungus, bacteria, and mold can attack roots.

One of the disadvantages of hydroponics is that in a controlled environment, pests thrive. In a natural environment, pests have predators or changing conditions that prevent them from overwhelming an ecosystem.

All these germs survive in many types of conditions but thrive in warm, stagnant, humid places.

Phytophthora

Phytophthora, which is Greek for “Plant-destroyer” is the one that will do the most damage to your plants. This mold is airborne and can also be carried in by bugs that touch water on the outside then come in.

As this mold incubates in your solution, they eventually coat themselves around the roots of your plants, stopping them from absorbing any nutrients or water. Your plants will soon die afterward, of course.

For Kratky growers like me, that can be a big problem. The Kratky method is passive, and the roots sit in warm, stagnant water which is a perfect breeding ground for the bacteria.

Prevention:

Everything should be cleaned and sanitized in your hydroponic system regularly. This also includes general areas like floors and shelves.

Keeping the area clean prevents bacteria, bugs, mold, and fungus from hanging out in your growing area. Most people eat the plants they grow, so you do not want to be eating that stuff either.

Replace your nutrient solution every 3-4 weeks. During the replacement, sanitize the reservoir with hydrogen peroxide, bleach, or PHYSAN 20.

An easy way to change out your solution is to drain the container, refill it with enough 3% hydrogen peroxide to cover most, but not all the roots. Dump the peroxide after 24 hours and refill with nutrient solution.

Wear gloves when handling concentrated hydrogen peroxide. You will suffer light chemical burns like this. If you are ridiculous enough to get it on you like me, then wash with lots of soap and cool water.

The discoloration should fade after a few hours. This burn is from 34% hydrogen peroxide.

PHYSAN 20, which is another type of disinfectant, kills bacteria, fungus, mold, and algae in hydroponic systems. It can be used as a general disinfectant for cleaning tools, benches, planter trays, contaminated pots, and soil.

It is excellent for controlling bacteria and fungi on seeds, seedlings, it kills the bacteria and not the plant.

Note: This is the best solution to use if you have algae problems

If your growing lettuce with the Kratky method, however, you should be able to grow fully-grown lettuce in one nutrient batch.

Lettuce usually doesn’t go into its final container until after it has been germinated for several weeks in a separate germinating tray.

I use a simple Tupperware container. The lid cracked, so I use it for germinating instead of throwing it away.

Some people like to keep the lid on to raise the humidity, but lettuce is super easy to germinate, and I like to keep air flowing around it to prevent mold, mildew, and fungus.

Oxygenate the Water

Can a Plant Recover from Root Rot?

Once a plant shows visible damage to the green part, it is often too late to save the plant.

Even if the plant survives, the foliage that is damaged will not become healthy again.

Your plant will have to grow new and healthy leaves to replace the wilted ones.

It is usually best to trash the plant to prevent the infected plant from spreading the disease to other, healthy plants.

However, if you notice root rot early you can cure it before it causes too much damage.

First, inspect the roots, if all the roots are mushy and brown, then it can not survive. However, if you see some white and strong roots, the plant may salvageable.

Root rot often begins at the extremities of the roots and works its way upwards so you may see some parts of the root brown and some white.

If you think the roots can handle it, take the plant to your sink, and gently rinse the slime off it.

Remember, root rot makes the roots very weak and a lot may fall off in this process. I would not recommend this procedure unless you visibly see white and healthy roots that can handle the rinse.

If you notice any signs of root rot, drain the nutrient solution, and refill with 3% hydrogen peroxide. Allow the roots to soak for 12-24 hours to disinfect the container.

Roots can handle the solution, but the smaller bacteria, mold, and fungus cannot survive the sterile solution.

Another treatment you can use is Physan 20 Concentrate. PHYSAN 20 is a broad range disinfectant, fungicide, virucide, and algaecide which effectively neutralizes most forms of bacteria from your solution or plant surface.

It is a disinfectant. You can pick this up online or at your nearby hydroponics store.

Conclusion:

Root rot can ruin your hydroponic experience. However, with the right tools and knowledge, root rot becomes a minor issue.

Adding a simple air bubbler to your hydroponic system to oxygenate your system will cut out a lot of problems growing your plants.

I recommend using them in all types of systems, including Kratky in certain conditions.

Did you this article helpful? Tell me a time where you experienced root rot.

Want some ideas on what types of plants do well in a hydroponic system? Check out my blog.

Ruddshomefarming

Easy Ways to Prevent Root Rot in Hydroponics

What Does Root Rot Look Like in Hydroponics?