Crown rot is like the ‘He Who Must Not Be Named’ of orchid care! But what is crown rot, is it so deadly and difficult to spot, and how can you fix it?
What is crown rot in orchids? Crown rot is where the crown, i.e. the top of the stem, begins to rot. Bacteria or fungus will cause the rot, but neither can have an effect unless the crown contains standing water. Water gets caught between leaves or directly in the crown and allows bacteria or fungus to multiply. The crown then becomes soft and yellow, and eventually dies. Crown rot will kill your orchid unless it is treated. It can be treated with hydrogen peroxide, and prevented with proper watering technique.
The guide below explains everything you need to know about crown rot. It starts by describing what causes crown rot, as well as the symptoms you’re likely to notice. To finish we’ll explain exactly how to treat crown rot, and why sometimes it can’t be fixed at all.
What Causes Crown Rot in Orchids?
Before we begin, we should make one thing clear. Your orchid’s crown is the top of its stem. The stem is the central body of the orchid, which rises up from the roots, and has leaves coming off of it at opposite sides. The stem isn’t the same thing as the flower spike, even though flower spikes look like the stems of other plants.
To locate the crown, place your finger on the tip of the topmost leaf and move it inwards until it’s precisely in the middle of the top two leaves. That’s where the crown is. Below the crown is the stem, which can be infected too, and similarly shouldn’t be cut open like the crown.
Crown rot, obviously, is where rot develops within the crown. There are two things that are necessary for this to occur: water and bacteria/fungus.
Getting Water in Your Orchid’s Crown
Rot will not develop in the crown unless water is placed in it, either accidentally or on purpose.
There are many ways that owners get water into the crowns of their orchids. They include:
- Misting the orchid too much. This keeps the crown moist permanently, never allowing it to dry out. That’s the perfect setup for rot to occur.
- Watering the orchid from above without avoiding the top two leaves. The leaves capture water droplets, which then roll down into the crown. You should avoid watering the leaves, and water the roots instead. This is an especial issue if you like to shower your orchids rather than bathe them.
- Not dabbing away any water that gets in the crown. Whether because of watering, misting, or something else, you should check for water in your orchid’s crown. If there is any, you can dab it away with tissue.
Certain things can make the likelihood of this happening worse. So, for example, if your orchid has grown straight upwards rather than at an angle, it means water can’t escape from the crown. But if your orchid is leaning out of its pot, like some of mine are, it’s less likely that any water that gets on the leaves will drip down into the crown.
Some people take different approaches, and there’s nothing wrong with that. Many owners point to the conditions that wild orchids live in, where of course they get wet in the rain, and of course they can get water on their leaves and crowns. But no matter how you choose to water or mist your orchid, you should ensure that the water doesn’t stay in the orchid’s crown for a long time. That’s how you cause rot.
Bacteria & Fungus
The second prerequisite for crown rot to occur is bacteria or fungus. Both are omnipresent, whether they arrive in your new orchid bark mix, through an open window, or in water. There’s no way to sterilize your orchid and keep it sterile over the course of its lifespan.
But bacteria reproduce much more quickly in the presence of water. That’s because they reproduce asexually by expanding and separating into two, and like us, they’re mostly made of water. It’s therefore an essential ingredient for them to multiply. The more water, the more bacteria or fungal spores.
What’s especially bad is if you allow standing water. This is water that can’t drain away, and doesn’t evaporate away. If you consistently water your orchid before this water has fully dried, it’s effectively permanently wet. This is what will cause the initial infection.
What Are The Symptoms of Crown Rot in Orchids?
Crown rot isn’t the easiest of conditions to spot. Rot on a leaf, for example, can be pretty easily identified and is also more easily treated. Crown rot, though, you have to be looking for to see (if that makes sense!)
Yellow Leaves, Particularly Near the Crown
The first sign you’re likely to notice is a subtle one. The leaves of your orchid, particularly the topmost leaves, will turn a light shade of yellow.
Now, there are a number of caveats to this as a symptom. The first is that there are many reasons a leaf might turn yellow. The first is if the orchid’s leaf is old, as all old leaves eventually turn yellow, wither and die. That is perfectly normal, which means that yellow leaves aren’t necessarily a sign that something is wrong with your plant. New orchid leaves can also be a light green color, verging on yellow, which again is fine. Overwatering can also make leaves turn yellow.
As such, you shouldn’t immediately assume that an orchid with yellow leaves has crown rot. But that could be the issue. The yellowness in crown rot spreads from the site of the rot, i.e. the crown. It then spreads up the leaf towards the tip. It’s a light yellow in color, slightly lighter than the light yellowy-green you sometimes see in new leaves.
If you’re not sure what’s causing your orchid’s yellowness, check that the other issues (like overwatering) aren’t affecting your plant. Check in your orchid’s pot to see if its mix is too claggy, or if it’s still wet a long time after its last watering. Check that it’s not wrinkly and old, far down the orchid’s stem, to see if the problem isn’t old age. If you can categorically rule out these issues, then it may be crown rot.
Wilting, Withered Leaves
The last sign you’re likely to notice is that your orchid’s leaves look old, dried and wrinkly. They will also droop, having seemingly lost their structure and firmness.
This occurs because the orchid’s leaf is cut off from its roots. The rot that has taken hold in the crown means that water can’t be transferred between the root system and any of the leaves above the level of the rot. It then dries out and dies in much the same way as it would if it dried out for any other reason.
The problem with this symptom is that it makes you assume that the orchid is underwatered. Withered and wrinkled leaves do signify that an orchid isn’t getting enough water, but that isn’t the only reason they occur. As such, if you do decide to water your orchid more, you could be making the crown rot worse. More water will enter the crown, and will hasten the development of the rot… Leaving you wondering why your orchid is giving you mixed signals!
At this point, it’s almost certain that you won’t be able to correct the problem no matter what you do. You can still try to fix crown rot with the steps below, but it probably won’t work.
How Do You Fix Crown Rot in Orchids?
The first thing to note is that you can’t always fix crown rot. The crown is a very difficult place to treat any health condition, and it can spread from the crown to anywhere else: any leaf, any root, and so on. Your orchid may be too ‘far gone’ to be saved. That doesn’t mean you can’t try, of course, but it does mean you have to temper your expectations before you attempt this rescue operation!
Can You Cut Away Crown Rot?
The key difficulty with crown rot is that you can’t cut it away. If the rot occurs in the root system or on a leaf, you can simply trim away any rotten part, and if you correct what caused the rot in the first place, it won’t reoccur. But you can’t do the same with the crown.
The problem is that if you cut the crown away, the orchid doesn’t know how to regrow it. Orchids can grow new roots and new leaves, but they can’t grow new crowns. As such, you have to try different treatment options.
Hydrogen Peroxide and Crown Rot
Since crown rot is caused by bacteria, you must sterilize or at least disinfect the infected area. This will stop the rot from spreading any further, and mean that your orchid stands the best chance of surviving. You can do this using hydrogen peroxide. Hydrogen peroxide is a chemical compound that kills bacteria and funguses, and is commonly used in cleaning products. It’s suitable for use on orchids, provided that you use the right concentration (3%—any higher is too strong).
Using hydrogen peroxide to treat crown rot is simple, but as for whether it works, that’s another matter. All you have to do is pour a small amount onto the affected area. You then leave it to sit for one minute, which is enough time for it to do what it does (disinfection). You must then rinse the area out and dab any remaining water away fully. When applied, the hydrogen peroxide will make a hissing, fizzing, spitting noise. This is normal. You could alternatively dab a piece of cotton wool in hydrogen peroxide and place that on the infected spot for a more even application. If at any point you are going to touch the chemical compound, e.g. to dilute it, you should wear gloves.
You should then repeat this process over and over again until it becomes obvious that the rot isn’t spreading any more. At this point, the hydrogen peroxide will have killed the bacteria or fungus that was causing the problem. It then won’t fizz, or at least won’t fizz as much as it used to. You must then prevent rot from recurring by changing how you care for your orchid.
Bear in mind that even this may not work. It depends how deeply the rot has infected the orchid’s crown and stem. You also have to be very careful to dab away any remaining hydrogen peroxide, which is diluted with water. In weak concentrations, the water could actually help the rot.
I’ve personally used hydrogen peroxide before with mixed results. I bought it originally to get rid of an infection in an orchid, and it worked fine. I then used it maybe a year later in an unrelated case, and found that it didn’t work at all. What I didn’t know is that hydrogen peroxide degrades over time into… Water!!! So if you arae going to use it, make sure you use a new bottle.
Does Cinnamon Fix Crown Rot in Orchids?
If you’ve owned orchids for a while, research them online, read books about them, or just talk to somebody else who owns orchids, you’ll eventually be recommended cinnamon! Cinnamon has known anti-fungal properties, and it used for various things from treating rot to sealing open wounds from a cut (…on an orchid leaf, that is).
I personally haven’t had great experienced using cinnamon. Whenever I’ve used it, it has only partially worked: so for example slowing down an infection rather than completely getting rid of it. I’ve had one orchid die from an infection when I used it, and on one that I still have, I tried it again. It didn’t even slow the infection this time, and I had to use an anti-fungal spray. It’s for that reason that I don’t use it any more. The problem could have been that I was using old cinnamon, the wrong kind of cinnamon, or something else—but whatever the reason, I don’t personally recommend it.
That doesn’t stop other people using it, and it seemingly working for them. So, if you want to give it a try, feel free. All you have to do is sprinkle it on the affected area and let it do the rest. There are a few problems with this approach, though:
- The cinnamon wouldn’t penetrate through to the inside of the crown, where the infection is.
- The cinnamon isn’t necessarily of high quality, and may be quite old by the time you buy it, losing some of its effectiveness.
- Cinnamon isn’t as effective at killing pathogens as something like, say hydrogen peroxide!
How to Prevent Crown Rot in the Future
Preventing crown rot is much easier than treating it, doesn’t require any special equipment or expenses, and is certainly not beyond the skills of a novice.
The first way of preventing crown rot is to water your orchid correctly. If you were to shower your orchid with a shower head on full-blast, plastering it from top to toe in water, lots of that water would pool up in your orchid’s leaves. This could be a precursor to crown rot, especially if you don’t allow it to fully dry before you water your orchid next. Instead, water carefully by emptying a jug of water into your plant’s pot directly onto its roots. There’s no reason to get water onto its leaves. If any does, dab at it with tissue and tilt your orchid from side to side so that it runs out.
Another way of preventing crown rot is to ensure there is enough air movement around your orchids. Wild orchids are obviously subject to the wind, and wind helps water evaporate. But if your orchid is kept in a still room with no circulation, any water in its crown will stay there as opposed to evaporating.