Hoyas, popular for generations, are adored by plant enthusiasts and collectors, who nickname them "porcelain flowers" or "wax flowers" for the waxy appearance of their unique blooms. They are commonly grown as climbing or trailing houseplants and blend well with any decor. Easy to care for, hoyas tolerate the climate in our homes well and make beautiful decorative plants.
History & origins
Natural environment
Recognizing Hoyas
Maintenance & advice
Watering
Cutting
Potting soil
Potting
Bloom
Temperature & humidity
Fertilizer
Lighting
Toxicity
Species
History & origins
Hoyas were introduced to the world of ornamental horticulture by Scotsman Robert Brown in the late 1800s. He named this genus of plants after a close friend of his, Thomas Hoy, who was also the gardener to the Duke of Northumberland.
Today, hoyas are making a comeback and can be found all over the world. If the conditions are right and the climate resembles that of their natural environment, they can survive outdoors. They are often found in Central and South America, for example.
Natural environment
Most hoyas originate from tropical regions of Southeast Asia, the Pacific Islands, and Australia. Some species are also found in more mountainous regions, which are colder and higher in altitude. Generally speaking, however, most hoyas prefer warm, humid climates.
Over time, some species have been so hybridized for various aesthetic attributes that they have lost characteristics that allow them to survive in the wild. They require controlled conditions and do not appreciate changes in their environment.
In nature, most hoyas are epiphytic plants. This means they cling to tree bark or rock faces to climb and reach the light exposure they need.
How to recognize hoyas
First of all, it is important to note that hoyas do not represent a family of plants, but rather a genus that belongs to the Apocynaceae family. To be more precise, hoyas belong to the Asclepiadaceae subfamily.
Here are some criteria that allow us to recognize them:
- They always have five-petaled flowers;
- They have a sap that helps them heal in the event of injury;
- Their flowers are always in umbels.
There are also differences in the fruit of Apocynaceae from that of other Asclepiadaceae . Their genetics also differ slightly.
Leaves and stems
Hoya stems contain a milky or clear sap (called "milkweed"), like most plants in the Asclepiadaceae subfamily. Most hoyas produce leaves that emerge in pairs, but there are a few exceptions, such as Hoya imbricata . The nodes found on the stems can produce adventitious roots as well as inflorescences. Hoyas also tend to grow long stems, which tend to curl around to hold on, before producing their leaves.
Inflorescence
Hoyas produce flower stalks from which flowers emerge. These stalks can bloom multiple times and will grow longer with each bloom. Composed of 1 to 30 flowers, hoya inflorescences are also nicknamed "porcelain flowers" or "wax flowers" because of their unique appearance and texture.
Care & advice: understanding the needs of each type of hoya
To understand and master the care of your hoyas, it is important to be able to differentiate between the various leaf types and their adaptations. This is often an excellent indicator of their native environment as well as their specific care needs. Some hoyas require more bright light while other species will prefer more subdued light. The smaller the leaves, the more light the plants will need and, conversely, the larger the leaves, the more the plant will prefer soft light.
Small leaves:
Small-leaved hoyas generally require more sun, as their smaller leaf surface area impacts their ability to absorb the light the plant needs. This type of hoya usually comes from sunnier locations.
Example: Hoya lacunosa splash
Large leaves:
This type of hoya has leaves that provide a larger surface area to absorb more light. Large-leaf hoyas typically come from less-luminous environments and are forced to adapt to these conditions to survive. These hoyas are often found hidden among other plants, which serve as support, in the wild.
Example: Hoya glabra
Variegated leaves:
Generally speaking, variegated hoyas need more light because the discolored parts don't produce chlorophyll. Since chlorophyll is essential for photosynthesis, this means the green parts of the leaves have to work harder to compensate for the lack caused by the white parts. These hoyas will also be more sensitive to overwatering, like other variegated plants.
Example: Hoya wayetii variegata
Thin leaves:
Like many other types of plants, thin-leaf hoyas generally need to be watered more frequently and require much higher humidity levels. They often come from places in the world, such as rainforests, where they never evolved to store water.
Example: Hoya cembra
Succulent leaves:
Hoyas with succulent or fleshy leaves have adapted to store more water in their leaves. They usually come from a drier environment and therefore require more infrequent watering.
Example: Hoya kerrii splash
Provide adequate watering for hoyas
When watering, wait until the top of the soil is dry before watering the entire soil completely. It is normal for your plants to require a little more water during flowering and active growth.
As explained above, it is important to keep in mind that the thinner the leaves, the more frequently you will need to water them. We recommend watering pubescent hoyas to avoid retaining too much moisture in the leaves and risking them rotting.
Is it necessary to prune my hoya?
It is best not to prune hoyas drastically after flowering to avoid cutting off flower stalks that could rebloom multiple times in the same spot. As mentioned above, hoyas tend to grow long stems before the leaves appear. Therefore, it is extremely important not to cut them too early as this can affect the growth of your plant. If these stems are constantly growing and not producing leaves, you can pinch the tips to start producing them more quickly. If after a while you notice that the stems continue to grow without producing leaves, it is possible to cut them back to create a more compact plant. Hoya stems usually seek to cling, so until they find a place to curl, they may continue to grow without producing leaves.
Choosing the Right Potting Soil for Hoyas
If you were to visit a tropical rainforest, you would discover that the soil there is primarily composed of fallen leaves, rotting wood and compost, as well as charcoal left behind by forest fires over time. By taking the time to provide a potting mix tailored to the specific needs of your hoyas, you will benefit from exceptional growth by providing them with an environment close to their natural habitat.
If you want to keep it simple, we recommend using our homemade hoya potting mix , which has been formulated by our specialists to meet the specific needs of this type of plant. Alternatively, you can create your own mix by combining a variety of substrates to create a potting mix that provides everything the plant needs while remaining light, airy, and offering excellent drainage.
To start, we recommend using a mix of about 20% high porosity potting soil to which you add 20% coconut fiber and 20% black pine bark . Then, you can add about 10% New Zealand sphagnum moss , 10% perlite , and 10% pumice . Optionally, it is possible to add 10% activated carbon to help control humidity and temperature variations and avoid the risk of fungal diseases.
Substrates such as coco fiber and black pine bark help retain moisture by releasing it slowly, without soaking the soil. Pine bark eventually decomposes, creating organic matter that will help enrich the soil. Other elements such as perlite, pumice, and charcoal will add aeration to the mix and help roots grow healthily without the risk of mold. Sphagnum moss, on the other hand, will help rehydrate the soil more easily.
Potting Hoyas
The best time to repot your hoya is in early spring when the plant is preparing to enter a period of active growth (usually from spring to mid-summer). If you need to repot at another time of year, don't worry. This normally won't cause a problem, and it's just possible that your hoyas will recover a little more slowly. When repotting your hoya, make sure you don't increase the pot size by more than 1 to 2 inches in diameter and always choose a pot with a drainage hole.
Flowering and pollination of hoyas
Not only do hoyas come in a variety of species with diverse foliage, but the beauty of these plants doesn't stop there. Hoyas are also known for their unique flowers, which are nicknamed "porcelain flowers" or "wax flowers." Many hoyas produce highly aromatic flowers that are used in the fragrance market, such as perfumes and lotions. There are a wide variety of scents, such as cinnamon, vanilla, chocolate, citrus, popcorn, and many more.
The flowers, as well as the leaves and stems of some species, are covered with tiny hairs or scales called trichomes. These are modified epidermal cells that allow the plant to dry more quickly to resist rot and fungal diseases. These trichomes also help protect the plant from certain insects.
Flowers are bisexual and have both male and female parts. They are also actinomorphic, meaning that the parts of a flower are arranged symmetrically about its center. The petals are fused to form a corolla, to which the corona, made up of the pistil, is fused, thus forming a sort of crown.
Pollen is collected in the form of small balls called pollinia. Pollinating flowers is quite complicated because each species has evolved its inflorescence to correspond to a certain type of insect. Thus, hoyas maximize their chances of pollination, and survival, since there is no risk of contamination with pollen from other plants.
Hoyas are pollinated primarily by nocturnal insects. This is why their scent is generally stronger in the evening. The warmth of their environment is also a factor that influences the intensity of the scent. Sometimes, hoya flowers secrete a sweet nectar that drips onto the flower to attract pollinators. The amount of nectar is never the same, and sometimes some hoyas produce so much that the plant owner must protect the flowers to prevent the nectar from spreading everywhere and attracting harmful insects.
Maintain a temperature and humidity that promotes hoya growth
Since there are several species of hoyas from a multitude of varied environments around the world, it is important to be familiar with the hoya species in your collection and thus be able to provide them with an environment suited to their specific needs.
The ideal humidity for most hoyas should be kept above 40%, preferably around 60% or higher. If the humidity in your home is too low, you can install small humidifiers or plates with clay pebbles covered in water to help maintain proper humidity.
Different hoya species also have different temperature requirements. For hoyas that come from more mountainous environments, and therefore prefer cooler temperatures, they will need to be acclimated to an environment ranging from 10 to 25 °C . For hoya varieties from warmer climates, it will be important to place them in a location that reaches at least 21 °C .
Generally speaking, most hoya species thrive in temperatures that do not fall below 15 °C and do not exceed 35 °C .
Fertilizing and Feeding Hoyas
During their growing period, you will need to give your hoya liquid fertilizer (frequency: every other watering). Preferably choose a fertilizer rich in potassium (such as seaweed or stimyla ). In spring, you can occasionally add a fertilizer richer in phosphorus to encourage the appearance of flowers. Hoyas also appreciate foliar fertilization, but it is absolutely necessary to have good ventilation to avoid fungal problems. Ideally, spray the underside of the leaves with a small droplet sprayer such as a mist sprayer.
The lighting needed for the development of hoyas
Like most tropical plants, hoyas do not go into true dormancy. However, when temperatures drop and are accompanied by dark days with very little light, hoyas slow their growth drastically and show no apparent activity until conditions improve. Plants grown under artificial lights and with uniform temperatures will continue to grow and even flower throughout all seasons.
Generally speaking, the absolute minimum for growing hoyas is twelve to fourteen hours of light per day. If you want your hoyas to flower, they will need approximately sixteen hours of light. Remember that all plants require a period of darkness (nighttime) similar to that provided in their natural habitat. Darkness allows the plant to stop photosynthesizing and use the energy produced during the day.
Some hoyas can tolerate too much bright light. This intense brightness will cause some stress in them and they will develop interesting colors, to the delight of lovers of these plants (for example: Hoya sunrise , Hoya sp.gunung gading , Hoya pachyclada new moon ). So-called "splash" characteristics will also be able to develop more with too much light. Variegata hoyas will tend to prefer a brighter exposure since they produce less chlorophyll for their photosynthesis. This will allow them to develop more vibrant colors. However, be careful of sunburn. It is always important to acclimate your plants to the new light, which must be offered gradually.
Are hoyas poisonous?
While many plants in this family are more or less toxic, some research has been done on the toxicity of hoyas in particular. It has been determined that hoyas are plants that are considered non-harmful to the health of humans and animals.
Our favorite hoya species
Hoya imbricata
Hoya imbricata is found throughout tropical Asia. It produces a single leaf per node, which forms a dome-like shape that attaches to tree trunks or other surfaces. These leaves can range from 2 inches to 10 inches in diameter. In the wild, ants use its leaves as a storage area for food.
Varieties: Hoya imbricata and Hoya imbricata green
Hoya caudata
This famous plant can be found in Southern Thailand and Malaysia, and has been seen more recently on the island of Borneo. Hoya caudata is found on limestone hills in low, dense forests. When the plant is young, it is covered in several hairs (trichomes), which it loses as it matures. When a new leaf develops, it is burgundy in color before turning green. This is a hoya that changes colors a lot, its final shade stabilizing only after a few months.
Varieties: Hoya caudata gold and Hoya caudata splash & silver
Hoya archboldiana
Hoya archboldiana is named after the famous American aviator and explorer Richard Archbold. This species was first discovered in Papua New Guinea. It is a hoya that produces very large flowers that can reach up to two inches in diameter.
Varieties: Hoya archboldiana white , Hoya archboldiana red
Hoya finlaysonii
Native to Penang, Malaysia, Hoya finlaysonii is named after one of the collectors who discovered it. Its leaves are particularly thick and hard, and its flowers give off a slight cinnamon scent. This hoya, relatively easy to care for, offers medium to fast growth and prefers a temperature above 21 C° .
Varieties: Hoya finlaysonii sukirin , Hoya finlaysonii splash, Hoya finlaysonii panggha , Hoya finlaysonii big leaves , Hoya finlaysonii chicken farm , Hoya finlaysonii nova
Hoya gunung gading
Hoya gunung gading , which translates to "Ivory Mountain," is a member of the Finlaysonii genus. It was discovered in Gunung Gading National Park in the Sarawak region of Borneo. It is a very popular hoya among collectors as it can display colors ranging from red to very bright orange, with strong sun exposure.
Hoya curtisii
Native to Southeast Asia, Hoya curtisii has developed small, mottled leaves that can turn mauve in the sun. It requires a lot of light to produce its white flowers and is sensitive to changes in its environment. Hoya curtisii likes temperatures above 15°C and high humidity.
Hoya carnosa
Hoya carnosa is the classic pink-flowered hoya. It is one of the easiest varieties to grow and is the parent of several hybrids highly valued by collectors. This type of hoya is perfect for beginners since it does not require a lot of humidity or intense sunlight.
Varieties: Hoya carnosa krimson queen , Hoya carnosa krimson princess , Hoya carnosa compacta albomarginata
Hoya callistophylla
Its name comes from the Latin words kallisto and phylum , which mean "most beautiful leaves." As its name suggests, its foliage is adorned with veins and is magnificent. This hoya has evolved to retain water in its leathery leaves. Its flowers are red and yellow with a cream center.
Hoya pubicalyx
Hoya pubicalyx is a very easy species to grow and is a perfect choice for beginners. Its flowers can range from black to white, pink, and purple depending on the hybrid. It offers one of the fastest growing hoyas.
Varieties: Hoya pubicalyx "Black Dragon" , Hoya pubicalyx "White Dragon" , Hoya pubicalyx "Royal Hawaiian" purple
Hoya kerrii
Named by Dr. Arthur Francis George Kerr, Hoya kerrii is easy to recognize. Its heart-shaped leaves are leathery and waterlogged. It grows slowly compared to other large-leaved hoyas and requires plenty of light to thrive.
Varieties: Hoya kerrii “Splash ” , Hoya kerrii variegata
