Hoya kastbergii was found during Dale Kloppenburg’s expedition to Borneo in the area of Bau, that the south-west of the city of Kuching (Sarawak).It grew as a epiphyte on a tree at a height of 5.4 m (17 feet) above the ground. The tree grew at an altitude of 300 meters above sea level. It was published in 2003, named after Swedish collector Arne Kastberg.
I received this plant as a cutting in 2007 and despite trying every horticultural trick in the book never bloomed until January of 2015. It is an easy growing plant with circular hairless leaves that are around 1 1/2 to 2 inches in diameter. It seems to be a completely unpredictable bloomer with some people getting blooms in the first year and other people never able to bloom it. I thought I was in the latter camp when it finally flowered for me after almost 8 years, in my basement grow tent ,with no warning. Here are the conditions under which it flowered:
Temperature: Night time 55-60 degrees Fahrenheit (12-15 degrees Celsius) Day time High 77°F (25°C). Lighting: Combination T-5 Fluorescent and LED lamps. Humidity: Day time RH 55% and Night time at 85%.
I think it makes a very beautiful specimen plant, and if you are looking for a carefree plant that you won’t have to worry about continually sweeping up flower petals, this is a top notch candidate!