Hoya darwinii was discovered in 1909 by A. Loher, who named it in honor of Charles Darwin in Darwin’s centenary year. It is endemic to the Philippines and found at different elevations in a few different provinces. It is also called the Ant Hoya, because like Dischidia pectinoides, it will form special leaves that turn into a ball in which ants will take up residence. The waste generated by the ants will provide nutrients for the plant in areas where there in little in the way of nutrients.
My first Hoya darwinii plant was purchased from Gardino Nursery on eBay way back in 2013. It was small, had about 10-12 leaves, and did not last very long at all. I had it growing in soil in a grow tent under T-5 fluorescent lights, and it began to lose leaves almost immediately. Trying desperately to save my plant I took a cutting and managed to get it to root, but the main plant died, and shortly there after the cutting, after growing a new leaf, died as well. Somewhere in 2017, I tried ordering a Hoya darwinii from Thailand in a group order and it arrived completely crispy and totally dead. I’m unsure if this counts as one of my failures as I never even planted it as there was no point. A good Hoya friend of mine in North Carolina sent me a small rooted cutting in 2018, and despite taking a little longer to die, it died none the less.
In the spring of 2019 I put together my annual 12 plant Thai order and decided to add both color variations of Hoya darwinii to the order. It was going to be the very last time that I tried to grow the plant. Both plants were considered large size and cost me about $29 each, and when the shipping cost were divided out among all plants, the total cost came to about $36 per Hoya. The box arrived from Thailand, and for the most part the plants arrived in pretty good shape spending about 8 days in the post. The Hoya darwinii were quite large, and I was generally pleased with them. The roots were grown in a coconut husk plug that was impossible to remove without cutting all of the roots off and re-rooting so I was faced with the task of deciding what growing mix to pot them up in?? I had failed with this plant a few times in soil, so I really did not want to go that route again.
I opted to pot both darwinii up in four inch net pots using a modified bonsai mix in which I had added a little fine orchid bark, charcoal, and vermiculite. I then trellised the using a rabbit wire trellis that I made myself. By using the net pot, I was able to observe, by taking the pot out of the cache pot, exactly when to water, and was shocked at how little water this plant actually required. I am a compulsive overwaterer; I simply can’t walk by a plant and not water it. I have killed many a plant from too much kindness, and I think that is what happened to my previous Hoya darwinii. By being able to observe the sides of the net pot, I was able to go between 10 days and 2 weeks between waterings. Believe me it was hell trying to stop myself from watering, but I held to it. I went from a plant that would die almost immediately to a plant that was able to hold its own, put on a little new growth, and actually form a peduncle and begin to bud up.
The curse was broken and I was finally able to flower Hoya darwinii. It took a lot of perseverance, and a willingness to try new things to pull it off. I really think that it was worth the effort. It turns out that both of my color variations bloomed pink when one was supposed to be cream color, but I care not. The flowers have only the faintest of fragrance only on the day they open, and last about 3-4 days before closing and falling off. This was a challenging Hoya to grow, let alone flower. It is definitely not a plant for the beginner, or for the windowsill. It seems to grow best in South Florida, the tropics and anywhere you can provide very high humidity. It is extremely susceptible to root rot and must be allowed to dry out thoroughly in a coarse mix such as one used to cultivate bonsai. I am unsure whether I will be able to get this one to live for me long term, but am fortunate that I had the opportunity to get to work with it for a time.