Hoya Callistophylla Care & Bloom Guide

Hoya Callistophylla

The Hoya Callistophylla is an evergreen epiphytic climber that is found in the forests of Southeast Asia. It is a vining plant what grows long stems that can reach 15 feet or more.

And with one look you can easy tell that its leaves are its most striking feature.

These can grow to 10 inches long and 3.5 inches wide. They are likewise thick and have an elliptical shape. However, their most attractive feature are its dark green veins that run all over the light green foliage.

These patterns make the Hoya Callistophylla stunning to look at.

Of course, as with other hoyas, its flowers are just as lovely.

These grow in clusters of 20 to 40 flowers per bunch giving you colorful spherical balls. The flowers themselves have star-shapes. They feature brown, yellow and red borders round the white centers.

It is native to Southeast Asia particularly in Thailand, Malaysia and Borneo.

Hoya Callistophylla Plant Care

Light Requirements

The Hoya Callistophylla thrives in bright indirect or dappled light. While it will likewise do well in low and medium light, it is worth noting that you give it the best chances of flowering by leaving it under very bright, indirect or filtered light.

That said, you also want to keep it away from direct sun or very harsh lighting. Although the plant can tolerate some direct sunlight (1-2 hours daily) if you leave it there for prolonged periods of time, it will eventually sustain foliage damage including scorching.

Note that this won’t kill the plant. However, you do end up with ugly looking foliage which you’ll eventually need to prune.

Thus, the ideal spot to keep the plant is either is near the east or west facing window. Try to keep it away from the sun’s rays, although this is less of a problem with an eastern exposure since the morning sun is gentle.

Be careful with a southern window as it takes the strongest rays from the sun for the longest periods of the day. While this is great for some plants, it is often too much for the Hoya Callistophylla (and other hoyas).

Therefore, it is a good idea to place it a few feet from the window or provide some kind of protection like sheer curtains or a shade cloth to filter the light.

Outdoors, the best location for the plant is somewhere is partial shade.

 

Temperature

Although the Hoya Callistophylla also has specific climate preferences, this aspect is much easier given that it enjoys moderate to warm environment.

This comes from its native habitat which is Southeast Asia whose countries hug the equator. Therefore, they got a lot of sunshine all year round and no snow. A good way to compare the weather there is to look at Texas and Florida.

Similarly, Southeast Asia also gets battered by hurricanes the same way these two states do during the rainy season. Although there, they call it typhoons. But the strength of the winds are rains are similar in that they blow small homes and object into the air and can cause tremendous amounts of flooding.

However, because the Hoya Callistophylla lives underneath the forest canopy, it does get the benefit of the shade provided by larger trees, their branches and leaves.

As such, while it can tolerate hot temperatures, its ideal level is between 65 and 80 degrees Fahrenheit.

On the other hand, since the weather in its native habitat does not get cold (winters in Southeast Asia go down to about 55 or 60 degrees at most between December and February), it is less suited for snow and freezing winters.

Thus, avoid leaving it in places where temperature drops under 50 degrees, especially for long periods of time.

 

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Humidity

The other aspect of weather in the Southeast Asian region is that it is very humid. Average humidity hovers between 55% and 75% on most days. During the rainy days, it till go up to 85% or higher.

This is why the Hoya Callistophylla loves humidity and prefers 50% to 70%. As such, it is perfect for greenhouses, terrariums and grow cabinets if you have them.

However, thanks to its thick leaves which store water, the plant can tolerate dry periods longer than other hoyas. This also allows it to stay happy and healthy in lower humidity.

That said, try to keep humidity at 40% and higher if possible. It can tolerate slightly drier air, but the lower the humidity the higher the risk of dry, crispy and brown leaf tips.

Good humidity helps the plant grow faster and allows it to keep its lovely foliage shape and texture.

And while it does not have problems with very humid environments, you do want to temper this a bit as the higher the humidity gets, the increased moisture also ups the risk of fungus gnats, bacterial and fungal infections.

 

How Often to Water Hoya Callistophylla

Again, the Hoya Callistophylla’s thick succulent-like leaves come into play here. This allows it to tolerate some periods of dryness.

But this feature, coupled with the fact that it is an epiphyte means that you want to be wary of overwatering.

The reason is that its roots like to be able to breathe. Therefore, letting them stand in water is not a good idea as it increases the risk of root rot.

Just the same the other extreme is bad. That is, avoid letting the plant dry out completely for extended periods of time. This will eventually cause it to get dehydrated and sustain damage as well.

But between the two, overwatering is often a more serious problem because the plant is less able to bounce back quickly from it.

Knowing this, the best way to water the plant is to let the top 1-2 inches of soil dry out before adding more water. You can check this by sticking your index finger down to the second knuckle.

Then only water when the soil at that depth feels dry.

When watering, give it a thorough soaking. Avoid dousing the entire plant with water though. Instead, water directly onto the soil until the entire root ball gets saturated.

You’ll know when this happens as the moisture will start dripping from under that pot. That’s your signal to stop.

After that, allow the soil to completely drain. Make sure you throw away any liquid that ends up in the saucer under the pot (if you do use one).

 

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Hoya Callistophylla Potting Soil

The best soil for Hoya Callistophylla is a light, well-aerated mix that drains quickly. The plant also enjoys soil pH between 6.0 and 7.5 (which is slightly acidic to normal pH).

This kind of soil will hold just enough moisture to give the plant’s roots happy but drain the excess water so they don’t end up standing in water.

A good (and easy) combination is to use

  • 2 parts peat moss
  • 1 part perlite

Of course, you can use other components as well. The important thing is to give the plant sufficient (but not too much) drainage to avoid overwatering.

Thus, you can use perlite, pumice, vermiculite, orchid bark and even coco coir to do this. All of them work at varying degrees which is why they need to be combined with something that retains enough moisture to keep the roots well-hydrated as well.

Other soil options you can go with are:

  • Orchid mix with cactus mix and perlite
  • Coco coir, potting soil and perlite
  • Potting soil, perlite, charcoal and pine bark
  • Potting soil with succulent & cactus mix, along with some compost and charcoal

Don’t forget to use a container with drainage holes to let any moisture that drains from the soil get out of the container.

 

Fertilizer

When it comes to fertilizer, there are a few things to consider when it comes to the Hoya Callistophylla.

  • It is a light feeder
  • Therefore, Avoid overfertilizing the plant
  • But it does need fertilizer to grow optimally
  • It is not picky about the kind of plant food you give it. The more important thing is that it gets the nutrients.
  • Use a high nitrogen fertilizer most of the time for leaf growth and development
  • But when the plant is about to bloom, switch to a bloom booster (high phosphorus fertilizer) to encourage flowering instead of foliage growth

The biggest reasons for this that while the Hoya Callistophylla is for the most part a foliage plant, it also produces very beautiful flowers which grow in bunches (shaped as a sphere).

Therefore, once the blooms come around you want it them to be the center of attention. As such, the switch back and forth between kinds of fertilizer depending on whether or not the plant is flowering.

That said, the worst thing you can do is overfertilize the plant as this will be toxic to its roots.

Thus, feed it once a month or once very 2 weeks during its growing season dilute the application to half strength when you do. With a liquid formula, all you need to do is add more water before pouring onto the soil.

Don’t feed the plant during winter.

 

Flowers and Blooms

Speaking of flowers, once the Hoya Callistophylla matures, it will be capable of producing beautiful flowers. Note that it takes about 1.5 to 2 years or so before it reaches this stage (if start from a young plant).

Therefore, you do need patience.

That said, the blooms are worth the wait as they are gorgeous. The flowers themselves are small. And they come in star shapes that feature a white-cream color with yellow, orange and red borders.

As mentioned, the flowers grow in bunches, usually anywhere from 20 to 40 of them in a cluster. Although each of the flowers are only about 0.3 inches in diameter.

They usually appear during spring and summer although unlike other hoyas whose blooms last longer, the fragrant flowers of the Hoya Callistophylla stay for about 24 hours at a time only.

Note that the plant needs the right living conditions to bloom.

This is why sufficient bright, indirect light is important. Keeping it root bound also increases the chances of the plant to bloom.

 

Pruning

In the wild, the Hoya Callistophylla can grow to lengths of 15 feet and longer. Although this is not the case indoors.

That said, its vining stems can still grow quite a bit giving you anywhere from 6 to 10 feet if you let it.

As such, it is often placed in hanging pots and baskets to allow its lovely vines to drape downwards.

However, in its natural habitat the plant is often found climbing up trees using aerial roots. This allows it to get more bright light as it reaches heights above many other shorter plants.

With more sun, it is able to grow bigger as well.

Thus, it will happily climb up a support if you let it. A trellis or wire structure will let it wrap itself around the shape of the wires which you can use as décor.

As you can already guess by now, pruning is part of keeping the plant looking neat and tidy.

Its long training stems will need regular (but minor) trimming. You can use this as an opportunity to shape the plant and define its overall looks.

The one thing you want to avoid is very heavy pruning. Instead, trim in smaller bunches on regular intervals.

Similarly, don’t cut off the peduncles after the flowers have faded. You want to leave those as they new blooms will grow from them.

 

How to Propagate Hoya Callistophylla

Stem propagation is the best way to grow more Hoya Callistophylla plants. The good news is that it is quite easy to do this at home.

And you don’t need a lot of equipment or experience.

Here’s how to propagate Hoya Callistophylla from stem cuttings.

  • Use a sterile cutting tool to take a stem cutting from the parent plant. ideally, take a 4-6 inch long healthy stem with at least 1-2 nodes. The leaf nodes are essential as these as where the new roots will grow from. Without them, the stem will never propagate into a new plant.
  • If you can get a stem with aerial roots, all the better. Also, pick a stem with at least a few leaves on it.
  • Once you’ve selected the stem, cut before the node (and aerial roots).
  • Take the cutting and dip the cut end into rooting hormone.
  • Then plant the cutting into well-draining soil that is moist. Make sure you bury the leaf nodes under the soil. But remove any leaves that end up under the soil.
  • Keep the cutting in a moderate to warm spot that is well-lit (but no direct sunlight).
  • Water the soil regularly to keep it moist.
  • It will take about 4-6 weeks for the roots to develop and establish themselves.

The steps above are for soil propagation. You can likewise propagate the stem cutting in water.

  • Here, you’ll submerge the nodes and stem in water instead of planting it in soil.
  • Make sure to remove any leaves that end up in water.
  • Also change the water before it gets murky..
  • After 3 to 5 weeks the roots should grow and you’ll see them get longer.
  • When the roots reach about 1-2 inches long, you can move them to a small pot with well-draining soil.

 

How to Repot or Transplant Hoya Callistophylla

The Hoya Callistophylla only needs to be repotted once very 2 to 5 years. The reason for the large gap is that many growers like to leave the plant root bound because it increases the chances of flowering.

Therefore, don’t be surprised to see some hoyas that have been in the same pot for 5 or 10 years.

This feature, in combination with the fact that the plant is a moderate grower and its epiphytic roots means it does not need an overly large container either. And it will take time before it fills out that container.

When choosing a pot, go up only one pot size. And, make sure to use one with drainage.

 

Is It Toxic/Poisonous to Humans, Cats & Dogs

No, the Hoya Callistophylla is not toxic even when ingested. It is not poisonous to cats, dogs or humans. This makes it safe to keep around the house.

However, try to avoid any accidental hoya ingestion by pets or kids since it will still cause the usual unpleasant side effects when you eat something you’re not supposed to.

 

Problems & Troubleshooting

Pests

Mealybugs are the biggest threat to the Hoya Callistophylla when it comes to pests. Although mites, aphids and scales can come around as well. But for the most part it will be mealybugs you’ll likely experience if the plant does gets pest.

The important thing when dealing with these bugs is to spot them early and immediate treat them with water spray, neem oil or insecticidal soap.

You don’t want to wait because the will multiply quite quickly. And they’re much more difficult to get rid of when they turn into infesttations.

 

Diseases

The Hoya Callistophylla is quite resistant to disease. But it is not immune.

For the most part, diseases are brought about by too much moisture. Thus, humidity does in a way become your enemy here.

This makes it very important to let the soil dry a bit before adding more water. It also means making sure the leaves dry quickly after getting wet essential as this is where bacterial and fungal infections come from.

The most common problems include blight, sooty mold and root rot.