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The Changing Seasons

12 years ago

I thought I would start a discussion on the different seasonal changes experienced by Hoyas in nature and how to best grow and bloom species that are found in areas with pronounced seasons.

Many Hoyas grow in areas with high year round rainfall but others are specially adapted to survive up to two dry periods each year. A dry period can be totally dry for several weeks or a period of much less rainfall that can last for several months. Orchid growers are familiar with the deciduous species found in different Asian genera, many Dendrobiums drop their leaves and survive on energy stored in their pseudobulbs. Some Hoyas store their energy reserves in thick succulent leaves and this allows them to survive harsh conditions. I am not familiar with the specific needs of these Hoyas in regards to their rest periods but most of the orchids that share these same habitats will not flower if the rest is ignored. Often times there is a temperature drop that corresponds with the dry season and this is more pronounced at higher elevations. Some species may experience rainfall all year but with a significant reduction in rainfall which causes the plant to stop actively growing. If your Hoya stops growing during the winter it will benefit from being kept slightly dryer, especially if light levels are low. In the tropics the dry season is often the brightest time of the year for plants as many forest plants and trees also shed their leaves.

Here is a great link that shows different provinces in Thailand and what their yearly weather patterns are. The province of Chiang Mai in the North is one that is associated with Hoya species that have thick succulent leaves. If you look at the rainfall patterns you will see that during the dry season there is only 7.7mm of rain in January and this increases dramatically to 157.6mm in the wettest month of July.

The link at the bottom shows a paper on the climatic cycles of the Doi Tung region of Northern Thailand. There is a list plant species adapted to this seasonally dry area and several Hoyas are listed, they include Hoya kerrii, Hoya verticilata, Hoya thompsonii and Hoya sp. Doi Tung.

Other well known Hoya species that grow in these seasonally dry/drier areas are Hoya rigida and some forms of Hoya pottsii and related species like Hoya sp. Chaing Mai. These seasonal patterns also occur in other areas and continents where Hoyas are found and they include India, other Asian countries and parts of Australia.

I though I would start this discussion because Hoya growing is not yet as detailed when it comes to orchid growing but these plants share the same types of habitats. Unless there is collection data to accompany Hoyas it can be difficult to determine what type of culture they need. Often knowing a general geographic area is all you need to do a search for weather/seasonal info. I figure if a Hoya blooms well for you there is little need to change it's culture but other more stubborn bloomers may be trying to tell you that they would appreciate a seasonal change and this may be all that is needed to coax them into bloom. Thin leaved species obviously require year round moisture but the next time you look at your plants consider which ones are adapted to periods of low rainfall.


Here is a link that might be useful: Climate and vegitation info on Doi Tung Northern Thailand

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