Care of Wax Plant - The Wax Plant Flowers (Hoya carnosa)
The Wax Plant Flowers (Hoya carnosa)

The Care of Wax Plant (Hoya carnosa)

The Care of Wax Plant or Porcelain Flower (Hoya carnosa) does not require much effort on the part of the plantlovers. And this actually happens because it is a fairly tolerant vine with rather few, basic requirements.

Perhaps this is one reason why the popularity of Hoya carnosa, which has been cultivated for about two centuries in the Western world, although sometimes with transitions, remains largely satisfactory.

A second reason is that the choice of Hoyas for beautifying at least the interior spaces rewards. And it rewards not so much with its – by no means negligible – habit as with its magnificent and long-lasting flowering that accompanies the distinctly attractive sweet aroma emitted by its flowers.

And a third reason is clearly the present quite aptly dedication of "Kalliergeia" – although the careful reader will notice that it comes 200 years late.

But what is 200 years in the face of eternity?

The Porcelain Flower decorates indoor and outdoor spaces both in the form of climbing and hanging plant.

A Hoya carnosa Hanging Plant
A Hoya carnosa Hanging Plant
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Light & Location of Hoya

One fact remains indisputable, that the Wax Plant grows in conditions of both moderate and strong intensity of indirect lighting, but thrives in the latter case. Thriving means that it grows vegetatively and also that it shows abundant flowering – a goal that most likely meets the expectations of the plantlovers.

Exposure of plant to direct sunlight, if it is for a few hours in the morning, does not harm it – on the contrary, it is beneficial. But its exposure to direct midday sunlight is disastrous.

In indoor spaces with little or no natural light, artificial light sources can produce wonderful results. This can be achieved by using, for example, fluorescent lamps with a luminous flux above 3230 Lumen (lm). The lamps should provide the plant with 12 to 16 hours of light, followed by total darkness until the 24 hour period is complete.

The recommended location in the house for the Wax Plant is near or next to a window covered by a curtain. The appropriate window orientation is north for the southern hemisphere, and south for the northern.

Placing the Hoya carnosa in an extremely bright bathroom seems like an excellent choice, provided that the exquisite aroma of its flowers diffuses only within this special and more or less – as usual – strictly personal space.

For the Wax Plants, whose climatic conditions allow them to be planted in the garden, the most suitable location is that which is under a tree or locations in partially shaded areas of the corresponding environment.

The Care of Wax Plant (Hoya carnosa)


The Wax Plant is another indoor plant native mainly to the tropics. It therefore feels comfortable exposed to temperatures between 18 and 32 °C.

The temperature requirements of the plant, when it is cultivated as an ornamental outside its native areas, vary according to the season and the phase of day/night cycle.

The minimum night temperature in winter should not fall below 10 to 12 °C, while the maximum daily temperature can vary between 22 and 24 °C. At such temperatures, among other things, the normal growth of Hoya during the coming vegetative season is favored, while its flowering is also promoted.

In summer the recommended minimum night temperature should be between 16 and 18 °C and the maximum daily temperature between 24 and 29 °C.

If Hoya carnosa is planted outdoors – in the garden or in the landscape – its suitable exposure temperatures are between 0 and -1 °C for minimum values and 34 to 36+ °C for maximum values.

The Care of Wax Plant (Hoya carnosa)

The Spectacular Inflorescence of Hoya carnosa
The Spectacular Inflorescence of Hoya carnosa


The Porcelain Flower seeks higher relative humidity values than most indoor plants. Its favorable growth values range between 40 and 60%, but the best results, both vegetatively and for increasing flowering, are close to the maximum value.

However, indoor relative humidity above 50% is extremely difficult for human living, while below 40% is extremely difficult for the plant itself, as among other things it increases the risk of being attacked by pests, such as for example from mites.

The solution to this problem is rather simple and is given by modifying the microclimate around Hoya. To achieve this, so that the plant enjoys a wetter environment, techniques – among others – include:

  • The systematic misting of the foliage (twice a week)
  • The use of a humidifier
  • The placing of a shallow tray or plate with pebbles and water at the base of the pot

At this point it is worth saying that it is not a bad idea to periodically clean the leaves of the plant, especially if misting is chosen. Because otherwise, the dust, debris and dirt that accumulates on the surface of their lamina mix with the micro-droplets of the fine mist, clogging the stomata and reducing the photosynthetic capacity of Hoya carnosa.

In other words, neglecting to clean Hoya leaves combined with misting them seems to be an ideal, effective and successful way of exterminating this wonderful plant.

As for misting, let the plantlovers keep in mind this too, that it should not be attempted for any reason during the period when the Wax Plant is in bloom.

The Care of Wax Plant (Hoya carnosa)

Watering of Wax Plant

The Porcelain Flower has moderate to minimal watering needs. The plant’s thick, fleshy leaves, with their waxy, shiny surface, contribute a lot to this, as they release extremely small quantities of water. On the other hand, overwatering must be avoided, because in combination with possible poor drainage of the mixed growing medium or substrate, it contributes to the exposure of the roots of Hoya to the risk of rotting.

Let plantlovers not forget that Hoya carnosa is an epiphyte that develops many aerial roots when it is in its natural state, and also that the presence of the air phase in the rhizosphere area is in great need.

We will not sound very original if we claim that the irrigation method of Hoya varies according to the season: in the winter period, small quantities of water is provided, the amount and frequency of irrigation increases accordingly in the spring and summer, and gradually decreases during the autumn period.

A reliable indication for watering the plant is when there is an almost complete lack of moisture in the first 2.5-3 cm of the surface of the mixed growing medium – during the period of growth and flowering. In winter watering is drastically reduced, taking place only shortly before the planting medium dries out completely.

Regardless of the season, watering is done with plenty of water, until the pot or planter is flooded. However, if there is a sauser at its base, since it is understood that the pot has holes, it is immediately removed when the drainage is completed.

The Care of Wax Plant (Hoya carnosa)

Care of Wax Plant - A Flowering Wax Plant Climbing on a Tree
A Flowering Wax Plant Climbing on a Tree

Wax Plant Fertilization

Regular plant nutrition helps, among other things, in their unhindered growth and optimal flowering. A source of nutrients is the mixed growing medium or the growing substrate as well as fertilization of any type.

The Wax Plant, without being the most demanding plant – a heavy feeder -, especially in terms of fertilization, also needs an adequate supply of the necessary nutrients.

And as much as the growing medium is a good reservoir of nutrients, adding the right fertilizer increases their adequacy and availability.

A suitable fertilizer for Hoya is one whose formula of the basic elements corresponds to the ratio 1(N): 1(P2O5): 1½ (K2O). In addition, the combination of the fertilizer with organic amino acid preparations results in the promotion of flowering.

The administration of fertilizers is recommended to be done by root irrigation, while the application dose depends on the general growth of the plant (and always following the manufacturer’s instructions). The frequency of application can be once a month, starting from the beginning of spring until the end of summer.

The Care of Wax Plant (Hoya carnosa)

The Pruning of Hoya carnosa

The Hoya carnosa plants will not bother the plantlover with pruning. Of course, if the plantlover wants to prune, can do so:

  • Pruning the long vines of the plants in order to form or maintain a compact habit of the Porcelain Flower
  • Drastically pruning the central stem to allow the growth of more lateral stems and side shoots

The best time to prune the plants is the first fortnight of spring.

But before the plantlover indulges in pruning, should seriously consider the way the plant blooms: the Wax Plant blooms – and bears fruit – on stems with a special function and appearance, the so-called "Spurs".

These stems grow laterally, and are short and thick. They are in some way homologous vegetative structures as those of the cherry and apple trees, which means that for almost no reason should they be cut, because they flower and bear fruit for many years.

The Care of Wax Plant (Hoya carnosa)

Care of Wax Plant - A Wax Plant Flowering Stem (Spur)
A Wax Plant Flowering Stem (Spur)

The Flowering of Porcelain Flower

The flowers of Wax Plant are borne on an umbel inflorescence (actually is a pseudoumbel). The umbel in turn grows on the short and thick stems, the ‘Spurs’ – which are perennial. The role and importance of the latter was discussed a little above, however it can still be said here that the more they are, the more abundant the flowering of Hoya will be.

On the other hand, the flowering of the plant is promoted above all by its exposure to high intensity indirect light. If the intensity of indirect light is reduced, Hoya carnosa may continue to grow vegetatively but flower little and/or not at all.

Flowering generally occurs from Spring and lasts until the end of Summer – sometimes longer. Each inflorescence displays flowers that remain open for up to 20 days or so. During the flowering phase the pot with the Porcelain Flower should not be rotated, just as the plant itself – we point it out again – should not be misted. Also, under no circumstances is it recommended to remove the withered inflorescences from Hoya carnosa.

Hoya plants take from 1 to 3 years to start blooming – a phenomenon that is directly related to the general growing conditions.

The Care of Wax Plant (Hoya carnosa)

Potting - Repotting & Potting Media

One of the special characteristics of the fleshy Hoya is that it likes to have its roots quite bunched up – almost tightly. This fact not only satisfies the plant but also the plantlovers, because it frees them from the trouble of annual transplanting.

But before starting the transplants, the plantlovers must transfer the planted – usually – in a nursery pot Wax Plant to a planter of his preference. And of course its form, colour and shape will only meet its own aesthetic criteria, but the size should keep up with the plant’s requirements, so that it can grow and bloom normally. So both for the initial and subsequent transplants, the planters should be slightly larger – just one size – than the previous ones.

Regarding the frequency of repotting, it can be carried out every two or three years.

Now in relation to the selection of the appropriate soilless growing medium, the plantlovers will be faced with a dramatic dilemma of existential dimensions: should they use ready-made or prepare their own mixed potting media?

But, as is often the case, this too is a false dilemma. There are excellent quality ready-packaged potting mixes available from the market. If they still want to prepare their own, here they meet the maximum help of "Kalliergeia", in order to confide in them only the golden recipe of the most suitable mixed potting media, which is none other than:

  • 2 parts peat
  • 1 part of potting soil for orchids
  • 1 part potting soil for cacti
  • and 2 parts pumice for agricultural use

In any case, of course, the purchased or prepared potting mix should have a neutral or slightly acidic pH reaction.

Pests and Diseases

As long as the growing conditions are appropriate, Wax Plant will respond by remaining admirably healthy. But this can give rise to the envy of certain parasites, who will try to infest it.

Among these otherwise worthy of mention parasites are scales, mealybugs and aphids pests. Their treatment is carried out with a mixture of soap and water, which is applied by spraying. Once they are destroyed, the plant is rinsed with water (preferably distilled). In severe infestations, however, the recourse to special insecticide preparations, with approval for domestic use, is necessary.

Hoyas planted in garden soil are likely to be attacked by various nematodes belonging to species of the genus Meloidogyne. These pests are difficult to impossible to controlled.

Of the diseases, the most serious is that which manifests itself with root rot, due to the action of various fungi, which is usually due either to a failure in choosing the appropriate growing mixture or to the overwatering of the Hoya plants.

Infestations from these fungi are difficult to treat, and the recourse to special fungicides, also approved for domestic use, it’s pretty much a one-way.

Another disease of Hoya plants is botrytis blight. Botrytis blight is caused by the action of the fungus Botrytis cinerea, which can be controlled quite satisfactorily with special fungicidal preparations.

The Care of Wax Plant (Hoya carnosa)

Potential Issues

The following table lists various potential problems, their possible causes and their treatment within the framework of care of Porcelain Flower.

Browning of LeavesOverwatering, underwatering, excessive fertilizationWatering control, proper fertilization
Yellowing of LeavesAging, overwatering, nutrient deficiencies, inadequate lighting, pest action, cold draftsWatering control, proper fertilization, proper lighting, pest control, draft free location
Necrosis of shoot apexLow relative humidity, excessive fertilizationHumidity and fertilizer quantity control
Absence of floweringLack of light, wrong planter sizeExposure to high-intensity indirect lighting, transplanting into the correct planter size
Falling flowersExcessive wateringWatering control
Bud drop, yellowing, browningMoving - rotating planterPermanent position, immobile planter

The Care of Wax Plant (Hoya carnosa)


The References of the the deeply insightful article, which bears the unique and original title The Care of Wax Plant (Hoya carnosa), are presented by the greatest classic rock band Creedence Clearwater Revival with their always timely song Fortunate Son.

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