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The most important thing you can do to save an overwatered Monstera is to help it regrow the rotted roots.
Overwatering can quickly lead to root rot. Root rot stops the plant from being able to absorb water (ironically enough) and nutrients, as well as eventually literally rotting the plant.
Root rot is caused by a proliferation of bacteria. The bacteria are anaerobic, so thrive in soil that doesn’t contain any oxygen. Overwatered soil is dense and muddy, and ends up being low in oxygen.
What does root rot on a Monstera look like?
The problem with diagnosing plant problems is that plants only have a few symptoms and dozens of causes.
So the symptoms of underwatering, like having brown spots on the leaves, are often the same as the symptoms of overwatering to the untrained eye.
In general, if your Monstera is looking sad and the soil is very wet, check the roots for root rot.
Brown spots on the leaves
This one is super useful to newbies because there aren’t many issues a Monstera can have that don’t result in brown leaves, or at least brown marls on the leaf.
Pests, underwatering, over fertilising, sunburn, etc can all result in brown spots on the leaves.
Sunburn and overwatering, in particular, can look similar.
If the brown mark is across the bottom of the Monstera leaf, and is pretty dark in colour, it could be overwatering.
This is more common to overwatering, BUT yellowing leaves can also be a sign that the leaf is being, er, retired by the plant.
Usually, older leaves go yellow and eventually fall off. The Monstera extracts as many nutrients as it can from the leaf – hence the change in colour. However, if your Monstera is growing big leaves quickly, the plant may decide that lower-down, smaller leaves aren’t worth maintaining. The leave will yellow off and die, even if they’re not technically old.
In general Monster leaves that are being retired go a more vibrant yellow tone, and root rot leaves are a more sickly yellow, but for one thing that’s not much use if you have nothing to compare it to, and for another, the yellow-ness varies from plant to plant.
If your Monstera leaves are all turning yellow, there’s probably an issue with overwatering. If it’s just a couple, check the soil and roots.
When I say ‘check the roots’ we’re looking for brown and mushy roots. Some roots are naturally brown, so definitely check the texture. You can also look for a smell.
Look for a smell??
Smell for a smell sounds weird.
CHECK FOR A SMELL.
Yeah, we’ll go with that.
I have no idea how to describe the smell to you. All I can say is that I think soil usually smells nice, but root rot doesn’t.
Leaves are drooping
Leaf droop is a bit of crap symptom, because some Monstera are naturally droopy and others aren’t.
I have one that gets super droopy when its thirsty (I can only assume she was raised by peace lilies) but I’ve never encountered another one that did that.
Still, if your Monstera is looking sad and droopy, that can be a sign of root rot.
How do Monstera get root rot?
It’s all very well to say ‘overwatering’ but overwatering is not always as simple as watering too often.
By the way, don’t worry about giving your Monstera too much water when it’s watering time. THat isn’t really a thing. Soil can only hold so much water (though read on for soil information). The key is to not water too often. It’s the frequency of watering rather than the amount of water you give that tends to cause issues.
Too much water
As I just said, you don’t need to be working out the volume of water to be giving your plant. Wait until the soil is dry, and then thoroughly soak the potting medium.
Some people prefer to give a little bit of water more often, some people like to really flush through the soil repeatedly.
It honestly doesn’t matter which you choose – all that matters is that the soil is allowed to properly dry out between waterings.
It shouldn’t get absolutely bone dry (we’re looking at around a 2 on the moisture metre), though Monstera are fairly drought tolerant, and absolutely don’t water if the soil is still wet.
In my experience the type of soil you plant your Monstera in depends on your habits (do you over or underwater?) more than the plant.
I’ll discuss potting mix in the next section, but here I just want to ensure that your pot has drainage holes.
Personally, I think drainage holes are necessary. I’m an underwaterer, so I like to really soak my plants when I eventually get around to watering them. If the pots didn’t have drainage holes, my plants would be sat in water and would get root rot quickly.
A lot of people claim that drainage holes aren’t necessary, and I do agree BUT if you don’t have drainage holes you have to be careful about how much water you give your plants at any one time. I don’t like to dance so close to the edge!
Too dense of a potting mix
There are a tonne of articles about the importance of the right blend of potting mix for Monstera, but I firmly believe that if you can mix a substrate that suits your plant care habits, your Monstera will be happy.
Monstera are invasive species in basically every country that doesn’t get frost. They are extremely unpicky about what they grow in. Give them good light and something to climb and they’re pretty chill.
If you like to water your plants a lot, get a seriously chunky mix for your Monstera. If you lean towards the neglect-y side of things *raises hand* go for a denser mix.
This doesn’t mean you can put your Monstera in clay and still have it be ok BUT if you buy a store bought house plant soil and don’t amend it with bark and perlite, your Monstera will be FINE so long as you let the soil dry out between waterings.
If you’re really, really, bad at forgetting to water, then consider growing your Monstera in water. I grow my Thai Constellation hydroponically and it’s really happy. I add java moss to the water for oxygenation. I have a video showing you how I did it:
Too big of a pot
Big pot = more soil = can hold more water than the plant can use
I know that it’s tempting to use that big, beautiful pot that you know your Monstera will eventually grow into, but it can lead to overwatering by proxy.
Instead, fill the pot with….other stuff* and use it as a big cache pot for the smaller nursery pot.
*You can use old blankets/towels to fill up the pot. You could also fill the plant up with soil if you want but make sure that the smaller pot is in a drainage hole-less cache pot other wise you’ll get water moving between big pot and little pot and it’ll be a PITA to get watering right.
How long does it take for root rot to develop?
It depends. It can either be something that builds up slowly over time from consistent slight overwatering, or something that stems from a one-time incident, like accidentally leaving your plant standing in water.
Also, sturdy plants like Monstera can usually tolerate small amounts of root-rot causing bacteria, especially if they’re pretty established, but if something upsets the balance or weakens them (like pests) they can quickly develop root rot.
So the answer here is ‘anywhere from a week to several months’.
Can a Monstera recover from root rot?
Yes, Monstera recover really well from root rot. They’re pretty hardy plants that tend to be relegated to plants that can live in low light and low humidity. Give them bright light and high humidity and they’ll bounce back quickly.
If you feel like your plant looks grim and is too far gone, you can easily propagate them from their nodes. I have a whole article on propagating Monstera here.
How to treat a Monstera with root rot
By the way, you can use these steps on most plants with root rot.
Step 1: take it out of the pot
This seems like an obvious step that doesn’t need to be stated, but the reason I put it in is that I want you to appreciate that this is going to be messy. Go and get a towel or tarp, and get the vacuum cleaner ready to go.
Do it. Do it now. Put on gardening gloves if you’re fancy. I simply take a second to apologise to my fingernails, but you do you.
Step 2: remove as much soil as you can
Be gentle, and don’t be alarmed if a lot of the roots come away too. If they were healthy they wouldn’t be doing that. The trash, as they say, takes itself out.
When you’re finished, look at the root ball. Then look at your pot. If the rot has been going on for while, you may discover tha the pot is waaay to big for the root ball.
If you have significant rot, make sure the pot is only slightly bigger than the root ball.
Step 3: chop off any diseased roots
Anything brown and mushy has to go. You can use kitchen scissors, but run them under boiling water first.
Step 4: wash the roots in hydrogen peroxide
This is optional, and to be honest it’s not something I do (because lazy) but it will kill off any remaining bacteria. I have an article here on how to use hydrogen peroxide on your plants.
If you still have a significant amount of roots and the plant looks ok, you can put the plant back and go about your day. You may want to repot in dry soil, but you can also dry out the soil with a blowdryer and pot it up in the same soil.
Obviously, you risk there being some bacteria in the soil, but I’ve repotted in the same soil dozens of times and root rot hasn’t returned – if you care for your plant properly and stop overwatering then the bacteria won’t be able to thrive as it did before.
Don’t be discouraged from taking these steps because you don’t have fresh soil and hydrogen peroxide. A rinse under the tap will remove some bacteria, and you can spread your soil out on a tarp (or some plastic bags) to dry. The important thing isn’t to make everything sterile – it’s to remove what you can and then reduce the chance of the bacteria multiplying in the future.
Re-root if necessary
The best approach to rerooting is to treat the plant like a propagation.
You can do soil, but I think water is more convenient. Use warm water and an air stone/oxygenating aquatic plants for best results (an aquarium is perfect, but don’t go setting one up just for this – it is NOT worth the hassle).
Rehabilitate in a grow tent
I’m getting quite attached to the idea of having one of those big silver professional grow tents in the corner of my room but they’re not really practical for the vast majority of us.
Aaaand Monstera tend to be too big to put in a terrarium.
So what to do?
Well, a big, clear plastic bag or box will do the job. Or even a small room where you can crank up the heat (dry your washing in it to add humidity!). Bathrooms work well if they have the light and aren’t too cold.
A grow tent is just a controlled environment that is nice and warm, and has good light and high humidity. This is what your Monstera needs to recover. A balance of all three is important – light and warmth are fine with lower humidity, but low light, high humidity, and warmth might encourage a lot of fungus and gnats.
Should you propagate a Monstera with root rot?
It’s entirely up to you. If the rot has seeped into the stem (i.e. if the stem is brown and mushy) then yeah, you’re going to have to propagate.
But even if the plant itself looks crap – all the leaves have dropped off and it looks sad – you can still reroot it as is.
Personally, I would propagate. In order for a Monstera to grow into an aesthetically pleasing shape after recovering from a bad bout of root rot, you’d need to provide it with optimal light, humidity and warmth. If it grew even slightly leggy, it’d look weird.
If you live somewhere like Florida, then this is fine. But here in the UK, it’d probably be easier to chop, prop and start again.
How long does it take a Monstera to recover from root rot (and how to speed it up)
A bigger plant will take longer to recover, and you’ll have to prepare for it to look wore before it looks better.
How long it takes a Monstera to recover from root rot depends on how much light, humidity and warmth you can give it. In the middle of summer with a good humidifier, you could probably have roots in a week or two and a full recovery in a couple of months.
By the way, dead leaves can’t grow back, so you won’t have exactly the same plant – we can’t time travel here. By ‘full recovery’ I mean a plant that can sustain itself with its root system.
Bright light, high humidity and warmth will speed this process along.
Hope this helps, and as ever, leave any questions below and I’ll get back to you ASAP.