Well, my rotundiflora likes to dry out between waterings, as does polystachya. It's very likely your guess is correct, that they were staying damp too long. Plus, sphagnum degrades more quickly than other mediums, compacting around the roots. It's great for rooting Hoyas, but not a good long term medium.

I would go ahead and look at the roots, like you plan. It's easy to remove sphagnum by soaking it well and then gentling pulling it apart. You have enough rotundiflora there to reroot it. You would just cut it off below that node the leaves are coming out of, then press that node into the soil, with the leaves protruding. Best to do it before those leaves start going downhill.

I find I do most of my rerooting emergencies this time of year. You're not alone. I've done a couple already. Good luck!

I have to agree that sphagnum moss is not a good long term media for Hoyas. The only Hoya I grow in moss is Hoya microphylla and that's because it is in a terrarium where I constantly monitor it and where the top portion of sphagnum is alive. The living moss you are seeing in your pot is not sphagnum but another species that is using the dead sphagnum as a substrate.

When receiving rooted cuttings from overseas the plants must be sent without soil to be able to enter most other countries, this is because of soil nematodes which are agricultural pests. The moss is great for rooting cuttings but it is better to soak the moss and remove it in exchange for your usual potting mix once your cuttings arrive.

I would carefully check the root system of your Hoya rotundiflora before making any cuts as it might be just fine. If the roots look healthy then repot in your usual mix making sure the mix is moist. If bark is a component of your mix but the bark has not been soaked it will tend to pull the moisture from the potting mix at first and this can quickly dry out a plants root system. I recommend either soaking the bark or watching very closely the moisture levels in the pot for the first couple weeks.

Mike

Thank you for your reply GG and Mike. It was the moss growing on top of the sphagnum that made me think it was not a suited medium. Because the moss would not have grown if the moisture level wasn't high. After reading GG's post I went straight to the rotundiflora and carefully pulled off most of the sphagnum moss, and the roots seem to be ok. I'm a bit worried the lowest part of the stem with roots are starting to wither, so I'm going to snip the stem in half. I'll leave the top part of stem and roots, and repot it in my own mix of perlite, bark and chunks of cocos fiber mixed with a little bit of compost.

When I came back to my computer to post pictures of the roots I saw Mikes reply, and was reassured that I had done the right thing. LOL Thank you again! Here are the pictures of the roots, there's still some moss attached to them, but they seem to be white in color and don't look rotted. I'll still snip it in half though, as the stem looks a tiny bit more mushy-ish at the bottom (not yet mushy, but could be if left the way it is).

Here are the pictures (all the brown stuff is the moss attached to the thin white roots):

Yeah it looks like you caught it in time. :) Yay!