I recently up-potted Hoya danumensis, between that and spraying the plant with sulfur, it seems to have helped it bring its buds to term. In the past, I have had almost constant bud drop.

I hope to bring this plant back in the future when I have had the chance to grow it for more than a few months. Right now I would have to rank it pretty high for both its beauty as a foliage plant and its ability to flower quickly right out of the gate!

These plants just happened to be flowering at the same time:

I can find very little online on the origins of this plant; the best I can come up with is that it hails from Rangsang, Indonesia. There is a movement right now in the Hoya world to lump many previously separate species into single species with different clones dependent on locations and the like. I suspect that Hoya sp. Rangsan will be lumped in with Hoya latifolia. The flowers are identical to the flowers of macrophylla and polystachya, which are now all called Hoya latifolia.

Hoya sp. Rangsan is primarily grown for its splashy leaves. My leaves would look a lot nicer if I hadn’t sprayed the entire plant with sulfur as a preventative against the dreaded flat mite!

Hoya sp. Rangsan flowered for the first time only four months after starting it from a cutting. So if you are looking for a quick bloomer this one would definitely fit the bill!

The cutting rooted very quickly in coconut husk with a little perlite thrown in, which right now is my medium of choice. I rooted it in June and it grew well from the start.

Hoya sp. Rangsan came to me as a nice cutting from my friend Robert Beckman. It has been in the trade for a few years now, but was not really on my radar.

If you are a collector, I think you have to assume that you have flat mites on at least some of your plants. You also have to assume that any new plant or cutting that you take in will have them. If you grow outside almost exclusively, I believe that frequent sprayings with the hose and natural predators of these mites can keep them at bay to a degree, but if you exclusively grow indoors, you will have a problem at some point.

I cannot tell anyone what they should do, but after only 3 weeks spraying everything with sulfur has made a huge difference for me. The number of Hoyas putting out new growth that have not grown for a very long time is remarkable. A couple of examples: H. serpens is throwing out crazy growth from many points when it just sat there for months. H. sp. Timor Leste had not done anything for months and had some yellow spotting on the leaves, sending up new leaves and vines. The same thing can be said for H. sp. Gunung Gading, H. undulata, and H. ruthiae. I would say that 90% of everything that I had that was either not growing or growing almost not at all is throwing out new growth. Below a photo of H. serpens that had not grown in months, and one that I have greatly struggled with over the past few years is busting out with new growth.

It has now been three weeks since spraying with sulfur; lets discuss what to expect. First there has been zero phytotoxicity; there has been no leaf drop even on the tenderest of new growth on any plant. At first the smell of the sulfur is kind of overwhelming, but over time it will dissipate somewhat. Still in the morning when I first open my tent, because of the high humidity, I have to wait a few minutes before entering as the sulfur smell is pretty intense.