A lot of problems that come with plants (both inside and out), stem from improper care. Not enough water, too much light, wrong type of fertilizer or the wrong size pot, to name a few examples. Most of these issues come from you and where you chose to plant.
But sometimes, there are other external foes you have to contend with. Things like insects or grazing animals. But under the surface of the soil, that can mean root rot, and it’s probably not what you think.
What Is Root Rot?
First of all, it should be understood that an over-watered or water-logged plant (see my list of treatments for this) isn’t the same as one with root rot. While it is true that too much water can encourage rot, it doesn’t strictly cause it. A fungus in the soil is the culprit, and it thrives in soggy soil.
It attacks the roots, leaving them soft and interfering with their ability to absorb water for the plant. Eventually, it kills them.
As is the case with most underground pathogens, you won’t know you have a problem until you see symptoms in the aerial parts of the plants, like the leaves and stems. Are your plants showing yellowing in leaves that start to curl, but seem to bounce back overnight? That’s a sure sign you have root rot going on.
Once you get the plant out of its pot (for treatment as discussed below), you can see the roots will be very pale and yellow, and probably getting soft or even outright mushy.
How to Prevent It
The best approach to fixing root rot is to prevent it from developing in the first place.
One smart idea is to plant varieties that have been bred to resist the fungus that causes root rot. Not all plants can be bought this way but it can be a life-saver if you are dealing with outside plants in an area where the fungus can’t be fully eradicated.
Just make sure to read the information before buying. Some plants may be resistant to one kind of fungus and not another (there are many possible sources).
Other than that, you should be taking care not to over-water. Get to know your plants and only give them a drink when they need it, not just because you happen to have time to do it.
Some plants should never be dry to the touch, and some should be left alone until the soil is completely dry to an inch or more from the surface.
Once you are watering on the right schedule, do your plants have well draining soil? Thick, heavy or otherwise compacted soil will hold on to water and start to smother the roots. That’s not good for the plant anyway, and can encourage fungal rot.
Looser soils are much better. Add in perlite, moss, coconut fiber or even a little sand to keep the water moving. For outdoor landscaping that you can’t easily dig up, try drilling 12 inch or deeper holes and filling with these materials around the root area of the plant.
It doesn’t remove the existing soil but still creates a bit more drainage to reduce the soggy environment.
Root Rot Treatment
Prevention is the best option because root rot is hard to treat. Take extra care with the watering of your plants, and hopefully that will be enough for you.
Be forewarned that a severe case of root rot cannot be fixed. Once the fungus is established and the damage done, you won’t be able to save the plant. If you catch the problem soon enough, you should be OK.
Having to fix root rot in houseplants is a little different than with outside plants. In either case, you should stop watering right away.
Houseplants are the easiest (relatively speaking) to take care of. Gently uproot the plant, and rinse away as much of the soil or potting mix as you can. Get rid of the old soil.
Examine the roots of your plant and there should be some soft or discolored roots. If not, you may not have root rot after all. Let’s assume you do.
Use clean, sharp scissors to trim away the most effected roots. Hopefully there is still enough healthy tissue left to keep the plant alive.
Repot in a new container with fresh potting soil. You should even give the pot itself a thorough cleaning or find a new container. Take extra care not to over-water your repotted plant, and hopefully it will recover.
For outdoor bedding plants, you can take some of the same steps to fix root rot as you would with houseplants. Dig up the plant and clean up the roots in the same way.
The only difference is that you shouldn’t just replant them back into the garden at this point. The soil still has fungus living in it.
Either find a new place to replant, or temporarily put your plants in containers so you can control the water issue better. A pot would also curb the spread of any root rot still lingering on the roots of your plant.
Once it starts thriving again, you can plant back into the garden.
Trees and Large Shrubs
For larger plants, shrubs or trees, it can be a more difficult challenge to fix root rot because you can’t actually move the plant to access the roots.
Stop watering until the first 2 inches or more is very dry, and then only water away from the trunk or main stem. For trees, there are roots as far out as the branches extend, so aim to water at that point.
Rake away any mulch around the plant to allow the soil to dry out property between waterings.
Avoid using any fertilizer at this point with your plants. Not only does root rot mess with water absorption, but also the intake of mineral compounds. Added fertilizer will just make it harder for the plant to absorb what it needs while it’s fighting the fungus.
Wondering about just buying a treatment product of some sort? That is going to be trickier than it seems because more than one type of fungus can cause root rot, and using any other type of fungicide won’t do your plants any good.
If you have access to a local extension office, you may be able to get a diagnosis, providing you are able to dig up a little bit of the roots to show them.
Stop the Spread
The fungus behind root rot is going to still be living in the soil, even if you are unable to save your plants and have to pull them up. You need to take specific care not to make matters worse and have it spread to other parts of the garden.
Don’t compost any of the plant material you pull up from that area. Either burn it or throw it in the trash. The same applies to any contaminated potting mix from inside if you are dealing with houseplants.
You can also go an extra step and clean your garden tools when you are working in an area with rot in it, before you go digging or working in an unaffected part of the yard.
The best approach is to really work on prevention so you don’t have to start digging up or getting rid of your plants. Don’t allow water to accumulate and definitely don’t let any root rot fungus spread around once you do have it under control.
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.