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.
Green is the colour 
Thank you for your informative website, which is so helpful! I have a beloved Hoya which I treated for root rot last fall. It recovered amazingly this spring, then got mealybugs. I cleaned those up very carefully and repotted my growing plant to accommodate a large trellis that I made for it’s copious vines. I made a new potting mix based on what I learned was appropriate for Hoyas as epiphytes. It looked okay despite the recent mealybugs, but stopped growing, and its leaves began to get thinner and curled. I found out the orchid bark had come with mites but I didn’t know then about baking it to kill pests. I treated the soil with organic insecticidal soap mixture and some peroxide solution. I checked the roots again and most of them are dead. I doubt that I overwatered and had excellent drainage, so I don’t know if I didn’t water enough or if it was the shock of the repot, since its outer roots had embedded themselves into its previous terra cotta pot. Maybe it was too much stress after the mealybug infestation. In any case, I still have long beautiful vines left with some life at the base of the stems, so I’ll have to root them. I have some questions about that. I also bought 3 new Hoya plants today from a local vendor (in case my poor Hoya dies). I discussed soil and care with this Hoya specialist (that’s all they grow and are the largest local distributor), but some of his advice contradicted what I have seen online. I would sincerely be interested in paying you for a private consultation, if you are open to that. I have researched a lot and have detailed questions, and would love to have a real conversation with a skilled and experienced gardener who really knows Hoyas well. Please let me know if that might be a possibility. Thank you again. Keep up the good work on your site! 🙂
LikeLike
Hey Jennifer! Thank you for such positive feedback, it means a lot! 🙂 I don’t feel up to selling private consultations though. 😀 I’m not a gardener and I am mostly also learning as I go. I’ve been keeping hoyas for about two years now and everything I know is more or less already written on this blog. For rooting the cuttings, high air humidity and light are the most important factors. There is an article on how I root my cuttings. Now in the summer I don’t use the heat mat, because it is hot either way. 🙂 Everything else I’m doing just as written in my article. And for the hoyas that you just bought, I would definitely repot them, to check the roots and to switch to a more familiar substrate. I always repot, because otherwise, I’m never sure when to water. Any advice on substrate and care can be contradictory because they depend a lot on the conditions they are growing in. So it is a bit of trial and error at the beginning to figure out how chunky or dense your substrate should be. Keep an eye on how long the pot needs to dry out completely. This shouldn’t take more than a week, if it stays wet longer, you need a smaller pot or chunkier substrate mix. I always use the smallest pot possible, sometimes I repot new hoyas in smaller pots right away, if they don’t have that many roots yet. You are welcome to post any further questions here and I’ll be glad to assist as much as I can.
LikeLike
Thank you for your reply, Hoya lover. Sorry to get back so late, as I have been super busy. I wanted to update you on my Hoyas. First of all, I did not repot my 3 new Hoyas right away. I gave them time to get used to being in my home environment. I only watered them once every 7-10 days, as they came in a dense potting soil mixed with perlite. Finally, I repotted them 2 days ago using your mix recipe, except for leca I put in lava rock and pumice. Moreover, I bought hydroponic basket style pots and clear orchid pots online. I drilled holes in the orchid pots, which I had seen recommended for orchids, also epiphytes. I did the same for tiny clear plastic cups for small rooted cuttings. I prefer terra cotta pots, but since I have had issues more than once with my Hoya, I now prefer to be able to inspect the roots regularly. Upon reporting, my new Hoyas’ roots looked okay, so I repotted them in the new pots & soil mix. However, after watering, they drained VERY quickly. I decided to soak them in solid pots of water for 10 minutes before draining thoroughly, a method I learned for orchids. I was hoping that would help the roots and soil media absorb enough moisture to last a few days. What are your thoughts?
LikeLike
Secondly, at the time of my first comment, I had made several cuttings from my original ailing Hoya and had put them in water to propagate. The glasses with charcoal developed algae later than the glasses with vermiculite. Several cuttings developed roots after the month passed. Interestingly, the glass with the largest root development also had root development in every cutting, even those I thought surely dead. I wonder if developing roots emit hormone that stimulates root development in other cuttings, that it gets into the water. I changed the water & cleaned the glasses, saved the rooted cuttings and out them individually in their own glass with fresh charcoal. From the original vines which I had cut, I made 16 more cuttings, dipped them in root hormone and let them dry 24 hours before putting them in water. I’m going to put the new cuttings in a propagation box. One cutting that had been in water for a month had enough roots to transfer to soil. I recently learned that you can ease the transition from water to soil by gradually removing some water and adding soil mix to a container so that the roots gradually get used to the new medium. I’m going to try this method to see if it works. My previous cuttings put in soil all rotted very quickly. Have you tried the “muddy water” method of transitioning from water to soil? Also, I read that the first soil for new roots should be a bit less chunky until the roots get used to particles—albeit well draining and aerated. Any thoughts?
LikeLike