Root rot is one of the biggest enemies of indoor gardeners. It lurks beneath the soil, making it hard to detect until it has done significant damage to our plants. It is also hard to combat once it has gained a large foothold on a plant.
My goal in this post is to help you learn from my experience of losing plants to root rot so you can work to save yours! The most difficult part for me was figuring out exactly what root rot looked like at the root level because dirty roots all looked the same to me!
I will show you exactly what root rot looks like by including pictures of a plant that arrived at my home with root rot and how I knew above and below the soil.
Then we’ll also go through what you can do when you find out your plant does have root rot AND what you can do to prevent root rot from visiting your plant in the first place. Let’s jump into it.
Table of Contents
What is root rot?
“Root rot is a general term that describes any disease where the pathogen (causal organism) causes the deterioration of a plant’s root system. […] Root rots can be chronic diseases or, more commonly, are acute and can lead to the death of the plant.”Brian Hudelson, University of Wisconsin-Madison Horticulture, https://hort.extension.wisc.edu/articles/root-rots-houseplants/
Root rot is essentially where your plant’s roots begin to die and decay. This causes the rest of the plant to collapse as well if not caught early.
What causes root rot?
Root rot in house plants is most often caused by a lack of oxygen around the roots of the plant. A plant’s roots breathe or respire oxygen, as well as absorb water and nutrients for the plant.
If a plant is in too dense of a potting medium, is watered too often, or is placed in a poorly suited pot, the roots struggle to breathe and begin to weaken.
At the same time, the dense, poorly aerated soil allows bacteria and fungi to thrive and prey on the roots of the plant, weakening them further into decay.
Summary for common causes:
- Plants that are overwatered
- Plants potted in too dense of a potting mix
- Plants that receive no to little light so they are unable to utilize water when provided
- Plants in a pot without a drainage hole causing them to sit in wet potting mix for long periods of time
- Plants potted in way too large of a pot where the small root ball can’t utilize the water in the large pot fast enough to prevent rot
How do you identify if your plant has root rot?
You can look for clues of root rot above and below the soil.
Clues above the soil are often a bit confusing because many of them can also be indicators of other issues.
Despite the confusion, it is best to rule out root rot by checking the roots anytime you are suspicious. Here’s why:
- Root rot is a serious threat to your plant and can make your plant very ill
- Root rot begins below the soil. Symptoms that show above the soil indicate that root rot has already progressed to a critical degree and must be acted on quickly to save your plant.
Above the soil indicators:
- Wilted, yellowing, or discolored foliage
- Random dieback in parts of the plant
- Color loss
- Stem base at the soil level turns brown or mushy
- Musty, unpleasant odor
The photo below is of a plant that arrived at my home in the mail.
This plant arrived in a pot. When I opened the package, I saw the yellowing leaf and the dark spot at the base of the leaf near the petiole which raised a warning flag for me that the plant was not healthy.
I immediately took the plant out of its pot and dug out its roots to take a closer look because I became suspicious it might have root rot.
Below the soil indicators:
- Unpleasant odor
- Brown, black, or discolored roots
- Soft, mushy roots
- Roots that break away easily
- Roots that when pulled on will lose their outer casing, leaving a thin string behind
This first photo is of the same plant I showed before, displaying most of its roots. I can see many worrying signs that root rot has indeed set in. In the following photos, I will zoom in on a couple so you can see them as well.
In the photo below, I have placed an arrow to show where the color of the root changes from an off white to a dark, unhealthy, green-black color.
This area has root rot and would need to be removed.
When I pulled on the area that had the dark green-black color, you can see that it melted away leaving a thin string behind. A healthy root would not have disconnected.
In this photo, I have pointed out more areas where thin strings are left behind after root has rotted away. Most likely the rotted root came off when I was removing dirt.
What can you do to control root rot?
If you have positively identified root rot, here are the steps I take to try to control it:
- Get the plant out of its current potting medium, which has the bad bacteria or fungi living in it
- Clean off as much dirt from the roots as possible
- If some roots come off while you are doing this, it’s okay. Those roots were probably not healthy anyway and needed to go.
- I will even run my plants under the faucet sometimes to clean them further so I can really see the state of the roots and what I am working with.
- Sterilize a knife or pair of scissors that can be used for cutting off any unhealthy root tissue
- I use rubbing alcohol or isopropyl alcohol to do this by simply washing my tool off with some before and after I prune an unhealthy plant
- Make sure to cut off any questionable root tissue by making cuts a little above the infected area. This will mean that you cut off a little of the healthy tissue to ensure all the bad tissue is gone.
- Spray roots with a diluted solution of hydrogen peroxide. This solution is to control any bacteria or fungus on the roots.
- To make the solution, use 1 tablespoon 3% Hydrogen Peroxide to 1 cup water
- Let the roots sit out and dry, unpotted, for a while. I’ve even heard some people suggest the plant be left out unpotted overnight.
- Then pot the plant in the medium of your choice.
- If your plant has little to no roots left, you will need to treat it like you are rooting a new cutting – you could root in water, in sphagnum moss, in soil, in leca (clay balls used in hydroponic setups), or various other media. To see an example of water propagation, click here to read my post.
- If your plant has a lot of roots left, however, you can resume regular care with slightly less water while the roots are prone to rot. After a couple of months, if your plant is doing well, you could ramp up the watering to a more normal schedule.
- Be sure to pot your plant in well-draining soil with lots of perlite, orchid bark, or other substrates that will increase aeration. To read more about how to choose a good potting mix, click here to see that blog post.
- Be patient while your plant recovers! This part is tough because it takes a long time for the plant to fully recover.
Do you have success stories of rehabbing a plant after it suffered from root rot? Share your story with us in the comments below!
What can you do to prevent root rot?
Check the roots
To prevent root rot, check the roots of a plant you want to purchase whenever possible to ensure they are healthy, white, and firm.
Give it aeration
Put your plant in a well-draining potting mix inside of a pot that has drainage holes to ensure excess water won’t collect around the roots of your plant.
Give it light
Ensure your plant is receiving enough light. Plants that aren’t receiving enough light won’t be able to use the water you provide in a timely manner, increasing the odds that root rot might take hold.
To learn more about signs that your plant is telling you it needs more light, click to read my blog post here.
Only provide water when your plant needs it
Water your plant only when the potting medium is dry or when your plant indicates that it needs water.
To learn more about how to properly water your plants or how to interpret your plant to know when it needs water, check out these blog posts:
Check the roots again anytime you are suspicious
If you see any suspicious signs that make you question the health of your plant, check the roots so you catch any potential root rot early!
Do you have other tried and true methods that work for you when battling root rot? Share with us below!
Resources used for this article: Click to read last week’s article: Better Ways to Know that Your Houseplant Needs to Be Watered
Click to read last week’s article: Better Ways to Know that Your Houseplant Needs to Be Watered