How to Care for Hoya Callistophylla?
A flowering tropical plant with exquisite foliage, the Hoya Callistophylla is native to Southeast Asia and can be found in certain regions of Australia and New Zealand.
As a succulent climber, this Hoya variety spends most its time climbing and growing on trees. Still, that shouldn’t stop you from displaying it in a hanging basket or a normal pot.
If you’ve never seen a succulent epiphyte, you’re in for a treat! Since it’s somewhat a meeting of two worlds, you’ll need to take the time to understand the care requirements of this Hoya plant.
Below, I’ve put together advice on how to care for the Hoya Callistophylla and what are some of the things you should pay extra attention to.
Size & Growth
The vines of this Hoya variety can reach up to 16 feet, when allowed to grow at its whim. Being the slow-growing vine that it is, it won’t be necessary for you to prune it back often.
While its waxy, oval leaves are mesmerizing due to their bright green color and dark green veins, the plant has another attractive feature – its blooms.
Star-shaped and pale yellow or orange with red tips, the blooms of this Hoya plant are exotic and remarkable.
As I mentioned, the plant takes well to growing in a hanging basket or in a staked in a regular pot.
Despite being a succulent, the Hoya Callistophylla isn’t as fond of sunlight as succulents are. In fact, you’d be doing a great disservice to the plant by exposing it to direct sunlight – the waxy leaves are sure to get scorched.
Still, this doesn’t mean the plant doesn’t crave sunlight. It’s just that it needs bright, indirect light instead.
I prefer keeping it in a room with a southern exposure, just to maximize the amount of light it gets. However, I do make sure to keep it a few feet away from the window, so that sunlight doesn’t reach it directly.
Don’t guard it too much from the light, lest you want your Hoya to never bloom. To produce the exotic flowers I mentioned, you need to ensure that the plant receives around 8 hours of dappled light during spring and summer.
In terms of watering, the Callistophylla behaves more like a succulent. At least when it comes to its aversion to being overwatered. Constantly wet feet in this plant equals certain death.
To avoid accidentally killing off your Hoya Callistophylla with too much water, simply allow the soil to dry between watering.
Check with your finger to see if the top two inches of soil are slightly dry. If still wet, don’t water. This is your typical soak-and-dry method that works for many tropical plants. And it works splendidly for the Hoya as well.
Depending on your indoor temperature and humidity levels, in spring and summer you’ll probably need to water more often, while in autumn and winter, you’ll need to cut back on watering.
If you notice that the plant’s leaves are starting to go yellow, it may be a sign of overwatering.
Closely watch the plant for any unusual signs such as droopy leaves and examine the moisture level of the soil.
With a bit of attention overwatering issues can be prevented. Also related to watering is severely underwatering the plant.
While the plant can survive some time off its reserves, let’s not forget that this is a tropical plant that’s also an epiphyte, so some moisture and humidity are needed to keep it alive and well.
The Hoya prefers slightly acidic soil (6.3 to 7.5) that offers exemplary drainage. If the soil is prone to waterlogging, its roots will start to rot, which cuts off the plant’s ability to absorb moisture and nutrients needed to survive.
A good mix to try is to combine one part perlite, one part peat, and one part orchid mix. This mix will provide good aeration and drainage, both of which are essential to keep the roots healthy.
Don’t use regular potting soil for this plant, especially not exclusively. Regular potting soil is too heavy, prone to compaction and waterlogging, none of which are good for the Hoya plant.
When planted in a pot (regular or hanging), make sure to fit the pot with drainage holes, so that excess water can evaporate.
Temperature & Humidity
As a plant that lives in warm climates, the Hoya plant needs temperatures between 65 °F and 80 °F. It can tolerate temperatures slightly above if humidity levels are high.
As for the lower extreme – the Hoya should not be exposed to temperatures below 50 F. This plant does not tolerate cold or freezing temperatures.
When grown outside during spring and summer, be sure to winterize the plant indoors. Make preparations to move the plant indoors when outside temperatures are nearing 50 F.
As far as humidity is concerned, its epiphyte nature prevails upon its succulent-like features and the Hoya prefers high humidity over a dry environment.
Aim for humidity levels between 50-70%, especially during spring and summer to help the plant grow more abundantly.
Should the air become too dry in your home, try to raise humidity levels with a humidity tray or a humidifier.
A fertilizer rich in nitrogen and phosphorus is the most beneficial to the Hoya Callistophylla. The plant doesn’t need too much fertilizer since it’s not a fast grower.
Yet its foliage will benefit from nitrogen, while its blooms will take well to the extra phosphorus from the feed.
Fertilizing once a month during spring and summer with a liquid fertilizer diluted at half-strength will keep the plant happy.
In autumn and winter, you can skip fertilizing. As the plant enters a dormancy period, it needs less nutrients to survive.
Potting & Repotting
Although a vining plant, it’s a slow grower that will take a couple of years to reach 3 feet. Repotting should not be on your list of priorities for about 2 years or so.
Use terracotta pots over plastic ones. For starters, they are more aerated and absorb moisture better from the soil.
The pot you’re using for transplanting, should only be 2 inches larger in diameter than the current pot.
Schedule repotting to spring when the plant re-emerges from dormancy, to take full advantage of its metabolism and growth.
How to Propagate Hoya Callistophylla?
The easiest way to propagate a Hoya Callistophylla is through stem cuttings. To maximize the rooting potential of stem cuttings, follow the next steps to harvest and root them:
- Harvest stem cuttings only in spring or early summer
- Use only green section that aren’t woody
- Size the cuttings so that they’re 5 inches and feature a few leaves and a leaf node
- Cut them 1 inch below a leaf node (the leaf node should stay on the cutting)
- Root in moist potting mix or water
- Keep in a warm place, out of direct sunlight
- Ensure moist soil, but not soggy
- Within a month, you should notice root activity
- Wait another 2-3 months for roots to become strong before transplanting.
Why are the Leaves of Hoya Callistophylla Turning Yellow?
Leaves turning yellow on Hoya Callistophylla can be a sign of overwatering, temperature shock, or lack of enough sunlight, although in this last case, the leaves tend to go pale, rather than yellow.
Check to see if the soil of the plant is wet, whether there are any fungi growing on the surface of the potting mix, or whether you can detect any foul smells. All these point to an overwatering issue.
Does the Hoya Callistophylla Plant Bloom?
Yes, the Hoya Callistophylla is a blooming plant with clusters of blooms formed on peduncles.
Each cluster features around 30-40 star-shaped flowers that are around 0.3 inches in diameter. Blooms will appear in summer.
However, you must make sure the plant receives at least 8 hours of dappled sunlight each day. Otherwise, your Hoya Callistophylla may not bloom.
Is the Hoya Callistophylla Plant Toxic?
Most Hoya plants aren’t considered toxic, so they’re generally safe to keep in a household with pets. The Hoya Callistophylla is not known to cause toxicity either.
That said, you may still need to watch your pets or kids and prevent them from ingesting parts of the plant. Particular allergies or choking hazards cannot be excluded, even if the plant itself isn’t toxic.
Because many houseplants are toxic to pets, use a general strategy to discourage pets from playing with your plants and limit their access to your houseplants.
An interesting fusion of two worlds – succulents and epiphytes – the Hoya Callistophylla enjoys slightly moist soil, warm temperatures and lots of bright, indirect light.
Overwatering and direct sun exposure seem to be the quickest ways to damage the plant, so pay extra attention to how you water your Hoya plant and where you position it.
Frost and cold temperatures are another enemy that must be accounted for. Even cold drafts or a badly closing window can induce temperature shock, so be careful to protect the plant during the coldest months of the year.