1. Plumeria spp
    1
    Plumeria spp
  2. Hoya finlaysonii
    2
    Hoya finlaysonii
  3. Hoya sp. IML 1438
    3
    Hoya sp. IML 1438
  4. Hoya multiflora
    4
    Hoya multiflora
  5. Hoya publicalyx
    5
    Hoya publicalyx
  6. Stephanotis floribundas
    6
    Stephanotis floribundas
  7. Hoya obovata
    7
    Hoya obovata

The Genus

The genus Hoya was established 1810 by Robert Brown after Mr. Thomas Hoy who had worked at the Scion House of Duke of Northumberland, as a chief gardener. It belongs to the Apocynaceae family along with other interesting species like Adenium, Allamanda, Nerium, Plumeria and Stephanotis. Hoya plants have a milky, latex-like sap and they are closely related to Asclepiadoideae. This are includes Asclepiuas, Huernia, Stapelia and Fockea. Natural distribution of Hoya ranges through Western India, Sri Lanka, Myanmar, Thailand, Taiwan, Southern China, Vietnam, Malaysia, Indonesia, North Eastern Australia, Philippines, Micronesia, Japan, Papua New Guinea, Solomon Islands, Samoa, New Caledonia, Fiji and Tonga. There are species that are limited to a specific habitat, while some species reported from various altitudes on various islands with different types of environments. The majority of Hoyas flower under extremely bright conditions, but under indirect light. For that reason in the jungle Hoya plants are found on top of the trees, hanging on branches or creeping on the trunk or other parts of vegetation. The plants are usually abundant along the river or near other water sources. Some species grow on limestone cliffs, exposed to salt water spray from the sea, while others have been found on mangroves in estuaries. Hoya plants are commonly called wax plants because of the waxy flowers or waxy appearance of the leaves of some species. All Hoya are evergreen plants that can be a vine, or scrambling, crawling or upright pendent or bush-like stems. 
Most are epiphytes (air plants) growing on top of some other vegetation or limestone boulders in their natural habitat. Sometimes seedlings are started on the umbell. When Hoya flowers redevelop from the rachis of a peduncles usually called spur. the spurs resembles a thickened stem scarred with minute bracts and arises from the leaf axil on each node. Depending on species, the spur persist as part of the plant after the leaves have fallen off or it may drop off after some time as well. The more spurs a plant has the more flowers it can produce. Hoya is a very diverse genus when it comes to appearance of individual flowers. The flower characteristics have been used to establish a sectional relation, but it does not support the species relationship based only on the flower. The size of the flower depends on different species and range from minute to large. To facilitate classification of species corolla shapes at complete open flowers are grouped into 5 types: revolute, reflexed, flat, campanulate and urn-shaped. The flowers of Hoya plants contains both male and female parts with symmetrical five partly-fused sepals, collectively named as “calyx”, five fused petals known as “corolla” and crown in the center, known as “corona”. Beneath the corona is the head at the edge of which are five bi-parted stigmas.  
Cultural requirements for this group of plants in SFLA is very similar to other tropical plants from around the world. Almost all species of Hoya are from humid forests or found near different bodies of water, such as rivers or creeks, swamps or seas and requires high or moderate humidity to grow well. Most varieties  will appreciate bright, indirect sunlight or semi shade, where more brighter condition will promote more flowering, while strong direct sun will be responsible for the reddish color of leaves and stems.

Many species can be grown in lower light intensities and will produce greener and taller plants. Optimum temperature for most varieties of Hoya will be 65F at night and 85F at day time, most species, with a few exceptions are warm loving plants and will not tolerate when temperatures drop down to low 40sF. Hoyas will grow most rapidly in evenly moisture, but not wet, medium. Depending of the size of the container it may take a week or few days to allowed top portion of the media to dry out before next watering, but in the same token never allow medium to dry out completely. Hoya plants can tolerate dry conditions, but it is not recommended to keep them from turning yellow or dropping leaves, all or partially. Most varieties will appreciate a good watering and will take a lot of water provided that the potting media is loose and well drained. Air movement is necessary to prevent developing different diseases and pathogens in the warm, moist and stagnant environment, specially in the summer month.
Moving air cools the plants surfaces and helping to dry out the plants if they are exposed to rainy weather conditions in SFLA. Potting medium for Hoya plants should be well aerated and has to have good drainage, but also keep medium evenly moist. For that purpose i would recommend to use  1/1 course canadian peat  and saw dust, peat and coconut coir dust, or all purpose commercially prepared potting soil and coconut coir. All of the above will have good structure and will dry out in the medium at a slower pace, depending on the weather. Nutritional requirements for Hoya plants is not difficult to meet, usually balanced slow release fertilizer such as Nutricote 18-6-8 designed for 180 days, at rate of 2 tsp per 6 inch pot or HB should be sufficient through the season. Occasionally use of water soluble 15-5-15 with extra Ca and Mg will help to control any minor deficiency symptoms during the growing month, especially from mid to the end of summer.    The plant container must allow good drainage and free air circulation. i use 5 inch azalea regular plastic pots for smaller plants and 6 and 8 inch hanging baskets for a larger plants. In general terms potting media for Hoya plants in SFLA should be porous, but still be able to retain some moisture. Hoya roots need enough water, but also need some H2O to breathe. When media in the pot become compacted, there very little space for the oxygen to get in and it may stay wet way too long and cause the tip of the roots to die off. On the other hand if mix is overly porous and it has plenty of oxygen, but not enough water holding capacity. The mix that i have used for a long time is very simple: 50%peat moss and 50% saw dust. Right now i am experimenting with coconut coir that is widely available in horticulture and orchid composted bark and  it seems to be doing well and could be the future of growing Hoya plants. The rule of thumb on the subject is if you have them growing well, there’s no need to change the recipe.