Nothing is perfect, not even the hoyas. 🙂 Unfortunately, they are extremely prone to root rot. Even if you manage to perfect the substrate, the watering, the light, you will still have an occasional problem with the rot. So do not beat yourself up when one of your darling plants starts rotting. It happens!
The most important thing is to notice it quickly and treat the plant right away. This will give you very good odds at saving the hoya.
What are the usual signs of the hoya roots rotting?
- The most obvious sign will be when your hoya starts dropping leaves. When they drop older, established leaves I always check the roots, unless it is just the oldest leaf (which is probably dying away from the natural causes).
- When some leaves look like they are rotting and are soft and mushy, yellow or brown, this almost always means that the roots are dying.
- When hoyas abort new growth or baby leaves, this too can mean they are rotting. They will also drop the baby leaves if you let them go dry for too long. But if your substrate is moist and the new growth dies away, check the roots.
- When a growing hoya suddenly and unexpectedly aborts new growth and starts stagnating, check the roots.
- When the leaves get black or brown fungal spots, check the roots.
- If your hoya is not thriving and you can’t find a good reason for it to be unhappy, check the roots.
Basically, if you find anything being weird and off with your plant, just check the roots first. I know hoyas are sometimes called stubborn, slow, and drama queens, but do keep in mind they are just plants! 🙂 If they are healthy and get the correct conditions, they will grow and thrive. If this is not so, you need to identify the problem and help them out.
How to identify which roots are rotten?
If you are used to aroids, you are also used to identifying the rotten roots by being black and mushy. It is hard to miss them.
With hoyas, this is not always the case. The first thing that you need to know, hoya roots will most often look white when already rotten. This makes it hard to identify the rot just by looking at the roots. To identify the rotten roots, you will need to gently pull on each root and see whether the outer sheet comes off easily. If the entire root or the outer layer of it comes off, the root is dead. If you are left with a white tiny, hair-like root, the root is dead.
If you have never seen the difference between healthy and rotten hoya roots, it will be hard to tell from the start. So don’t just look at them and say “The roots are fine” because they look white. Try pulling on them and you will know. The healthy roots are not soft but rather firm and will not come off due to the gentle pulling. And even though hoyas do have thin roots, healthy roots are never as thin as hair.
These are the healthy roots:
And these roots are completely dead:
How to treat the rot?
There are a few different scenarios here.
#1 You may find that only a few roots are rotten and most of them are OK.
In this case, you should only remove the bad roots. Cut them off right by the stem. Check the stem for the rot as well. If anything looks suspicious (colored dark or soft), remove those parts of the stem.
#2 If you find that most roots are dead, you will want to remove all of them and start from scratch.
This is not a big problem usually. As long as your stem is alive, you can always reroot a hoya. I believe in this case it is better to cut all roots off than to leave the plant with one or two healthy roots. This way it will grow new roots faster and more willingly.
#3 The rot is so bad that it affected the stem as well.
If the rot has already gotten to your stem, the hoya can still be saved. You just need to remove everything that is rotting or dead.
If I am not sure whether the stem is OK, I start cutting very small pieces of it from the bottom up. And I keep cutting until I see some sap coming out of the stem. The sap is either white or clear, depending on the species. Hoyas usually bleed heavily when you cut them. If they don’t, this means the part where you cut is not alive anymore.
So you just keep cutting until you are sure that you have reached the part of the stem that is alive. When in doubt, better cut some more.
After you are done cutting away everything that needed to be removed, dip the entire stem in the 3% hydrogen peroxide solution for a few minutes. This will disinfect the cuts. You can buy the hydrogen peroxide that is already diluted to 3% or buy the more concentrated version and dilute it with water yourself. I prefer to buy the 3% version as it is ready to go.
When you take the plants out of the hydrogen peroxide, you shouldn’t pot them up right away, nor put them directly in the glass of water or perlite for rooting. Leave them out for a few hours first, let them dry and heal the wounds. Otherwise, they will start rotting again.
Once the cuts are healed, you can pot them up in the airy and chunky substrate or begin to root them in the media of your choice.
I hope this helps. Let me know in the comments if anything is not clear or if you have any further questions.