The Hoya Coronaria is a rare species of hoya that you’ll not often sound for sale. In most cases, stores will either be sold out or don’t have the plant.
It is also worth nothing that in addition to being a well sought-after houseplant it is also used for medicinal purposes.
The most interesting thing about the Hoya Coronaria is there are many varieties around. As such, I’ve had a lot of questions asking me why certain Hoya Coronaria look different.
For the most part, you can tell from the color of their flowers.
Here, you’ll see quite a lot of different colors. And the varieties are based usually on the color of their flowers. Note that most flowers are bi-color where the star will have a different hue from the center of the bloom. However, some will have single colors as well.
This is a quick list of the Hoya Coronaria varieties and cultivars that I have come across (so far):
- Hoya Coronaria Red
- Hoya Coronaria Pink
- Hoya Coronaria White
- Hoya Coronaria Yellow
- Hoya Coronaria Malaysia
- Hoya Coronaria Blume
- Hoya Coronaria Gold Star
- Hoya Coronaria Narathiwat
And I’m fairly sure that’s not comprehensive by any means. That said, the most common ones are the Red, Pink, White and Yellow.
In any case, as far as appearance goes, the Hoya Coronaria has bluish-green leaves that have a fuzzy texture. So if you look at its photo closely, you’ll see a whitish, gray layer on it.
As mentioned the flowers come in different colors featuring larger star shapes with a waxy appearance that make them kind of look like plump plastic in a what.
They are very fragrant and last long. Most of the time they will appear during the warmer months. So make sure to give it enough light then.
The Hoya Coronaria is native to the lowland forests of Southeast Asia, namely Indonesia, Thailand and Malaysia.
Hoya Coronaria Plant Care
In the wild, the Hoya Coronaria receives partial sun or partial shade depending on what trees and plants surround it. As such, it does not tolerate a lot of direct sun or very harsh light because it does get shaded from the brunt of the sun’s rays in its native habitat.
That said, the plant does need light for photosynthesis. And while it can tolerate low light, it grows the fastest and produces most leaves when it gets medium to bright light.
More specifically, the Hoya Coronaria thrives in bright, indirect light.
In addition to better growth, it also needs good illumination to flower. So, if you want to see is beautiful colorful blooms, make sure you keep the plant in a well-lit locations.
Low light will not get the job done.
As such, an east or west facing window is ideal. You can likewise place it towards the south as long as it stays away from the sun’s rays or you filter they direct sun coming from that direction.
The Hoya Coronaria enjoys moderate to warm temperatures between 65 and 85 degrees Fahrenheit. It is native to Southeast Asia specifically Thailand, Malaysia, Indonesia and a few other locales there.
These countries all have similar weather – moderate to very hot.
During the summer, they are scorching hot reaching 100 degree Fahrenheit weather. In the winter (they don’t have winters or snow), the temperature dips to 55-60 degrees and not much lower.
As such, this is the range that the Hoya Coronaria is most comfortable with.
It will not have a problem with environments that hit 95 degree weather. But will struggle once things get below 50 degrees. Once things go under 45 degrees, that’s when problems start like stunted growth and other issues.
So, you want to avoid cold climates as the plant is not accustomed to it.
The good news is that it is well-suited to home temperatures which usually run between 65 and 75 degrees Fahrenheit (give or take a few degrees above and below). Therefore, you don’t need to do anything to keep it happy besides avoiding radiators and air conditioners.
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Another reason to keep the Hoya Coronaria away from heaters, radiators and air conditioners is that these appliances will dry the air.
In contrast, Southeast Asian weather is very humid averaging between 55% and 75% most days with rainy days getting to 85%.
As such, the Hoya Coronaria enjoys humidity of 60% to 80% in an ideal world.
Unfortunately, this is not something most homes can consistently maintain unless you live in the tropics or near a lake and other bodies of water.
Thankfully, its thick leaves do make things a little easier.
If you look closely as the Hoya Coronaria, you’ll notice it has thick, semi-succulent leaves. These are fleshy because the plant stores water in its foliage to help it get through dry periods.
It also allows it tolerate lower humidity without any problems. As such, it does well in humidity of 40% to 60%.
However, if you live somewhere with dry air, you will still need to monitor its leaves to see if they leaf tips get brown or crispy. If they do, it means the plant needs more humidity.
And you can help it out by misting it a few times a well or getting a humidifier.
How Often to Water Hoya Coronaria
Because the Hoya Coronaria has succulent like leaves, it does not need a lot of watering. In fact, watering it too often will cause it more harm than good.
So, avoid doing that.
Instead, adjust your watering routine based on the weather. The more light it gets and the hotter the climate is, the sooner the soil will dry.
As such, you do need to water more often during the summer.
In contrast, the cold weather, and reduced light in winter means moisture takes longer to dry in soil. So, you want to wait longer between waterings during wintertime.
On average, this comes out to around once very 5 to 8 days in the warm months depending on how hot it gets. And about once every 2 to 3 weeks in winter depending on how gold it gets.
- The best way to know how often to water your Hoya Coronaria is to check the soil. I like to wait until the soil is 50% dry before adding more water. You likewise have the leeway to wait until it is 75% dry.
- If you enjoy watering your plants (I have some friends who admit that they are “overwater-ers”), the best way to prevent overwatering is to wait until the top 2 inches of soil have dried before adding more.
- I know some growers who squeeze the leaves to tell. Thick firm leaves mean it still has moisture. Flatter, softer foliage means it lack water.
- I also have some friends who lift the pot. A light pot means the soil is dry while the heavier pot means the soil is still wet.
- Of course in addition to sticking your finger into the soil, you can likewise use a wooden stick. This will let you know until where the soil is still moist just by looking at the wet mark in the wooden stick. This way, you can gauge how much moisture the plant has.
- Another option is to use a moisture meter. Then, just reach the gauge.
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Hoya Coronaria Potting Soil
In addition to knowing when to water your Hoya Coronaria, it is important to use the right soil. The reason this is important is that the best way to water the plant is to drench it then allow it to drain.
This means flooding the root ball with water so the roots get the hydration they desire. Then, let the excess water quickly drain completely.
This mimics what happens in the forest when it rains. Its roots cling onto trees and get soaked by the rainfall. But after that, they quickly dry because they’re not in soil but get lots of air circulation.
So, in order to achieve this, the best soil for Hoya Coronaria needs to be lightweight, well-draining and have good aeriation.
This gives the roots lots of oxygen and allows it to dry quickly (and not stand in water for long periods of time).
So, in addition to knowing how often to water, it is important to know how to water and that that the soil does not retain too much moisture. Otherwise, this will negate your efforts of letting the soil dry out.
In addition to good drainage, ideally the soil has pH of between 6.0 and 7.5 (slightly acidic to neutral).
The simplest ways to achieve this is to use a combination of:
- 2 parts peat moss
- 1 part perlite
If you want to use potting soil, you can go with:
- 1 part potting soil with 1 part orchid bark
- 1 part potting soil with 1 part perlite
Any of these combinations will work well.
It is also a good idea to add some worm compost as topdressing to give the plant added organic matter.
The Hoya Coronaria will appreciate fertilizer. Although it does not need a lot of it.
Thus, the important thing is to feed the plant and avoid giving it more than it needs. Overfertilizing will cause more problems than underfeeding it. So, just follow the label and let the plant be.
You can use a balanced liquid fertilizer diluted to half strength once a month or every 2 weeks during the spring and summer. Don’t feed the plant in fall or winter.
Flowers / Blooms
The Hoya Coronaria will produce stunning blooms. These look similar yet different from other hoyas because of how its star-shaped flowers are. They’re sharper on the edges and they’re plumper so you don’t see them grow as close to one another even when they’re bunched up.
This make the plant unique and beautiful.
It is also worth noting that depending on the variation of Hoya Coronaria you get, the colors of the blooms can differ.
You can get cream, yellow, red, pink and varying combinations of these colors. Some have single colors while others have two colors.
That said, do have similarities in that they all take the same shapes and have similar looking centers.
They also need the same care to bloom. That is:
- Bright, indirect light
- Slightly pot bound
- Old peduncles
- Don’t move then when they’re blooming or about to bloom. Otherwise, they can abort.
Also, to encourage them, you can use a bloom booster (high phosphorus) to help with flowering and keep them longer.
In the previous section, I mentioned old peduncles. What I meant by this is that you don’t want to cut off the peduncles or spurs from which the previous flowers grew from even after they’ve faded and fallen.
That’s because the Hoya Coronaria will bloom again from these peduncles. So if you prune them off, you lose the potential blooms that can keep growing from these perennial spurs year in and year out.
And you have to wait for new spurs to grow before you see flowers again.
In addition to not cutting off the stalks, it is also worth noting that the Hoya Coronaria is a climber than can be hung in baskets to trail.
This works because it can grow to 5-6 feet indoors. Outside, it can reach between 8 to 12 feet depending on the conditions.
Thus, its length means that you will need to regularly do some light trimming to keep it looking neat and tidy. For the most part the cutting will be for aesthetic reasons (shaping and size control).
However, you also want to get rid of yellow, damaged or old leaves as well.
How to Propagate Hoya Coronaria
The most efficient way to grow more Hoya Coronaria is via stem propagation. This involves using stem cuttings then allowing them to root and grow into new independent plants.
You can use the stems you pruned off when trimming the plant. This way, you don’t just discard all of them.
Here’s how to propagate Hoya Coronaria from stem cuttings.
- Take a healthy stem cutting or use a stem that you’ve cut off when pruning the plant.
- The important thing is to pick a stem or stem tip with at least 2 nodes on it along with a few leaves on it. The nodes are the most important parts as the roots will grow from them. Without the nodes, you’ll never get a new plant.
- Move the lower leaves to expose the nodes. Keep the upper leaves for photosynthesis to help the plant grow.
- Place the cutting in water. I like to use a glass jar so I can see the roots as they grow and develop. But you can use any kind of container that holds the stem up and keeps the lower end with the nodes submerged.
- It takes just a few days for some white parts of new roots to show up. But you’ll need to wait about 4 weeks or so before there are enough roots to sustain the new plant. You also want them to get long enough.
- Once the roots reach 1-2 inches long you can put it up into soil
Alternatively, you can skip water propagation and root the cutting in soil as well.
- Instead of placing the cutting in water, dip the cut end in rooting hormone.
- The plant it into a small container with moist, well-draining soil. You can use 50% peat and 50% perlite.
- Leave the cutting in a warm spot with bright, indirect light and good humidity.
- In about 4 weeks the roots will grow and establish themselves in the soil.
How to Repot or Transplant Hoya Coronaria
Repotting is needed about once every 2 years or so. You only need to do so when the plant has gotten pot bound. And you don’t need to hurry either.
That’s because the Hoya Coronaria enjoys being root bound. In fact, it is in this state that it is more likely to bloom. Therefore, there’s not hurry to repot unless the plant is struggling or showing signs of stress.
Is It Toxic/Poisonous to Humans, Cats & Dogs
The Hoya Coronaria is safe for pets and humans. It does not contain toxic substances that can cause poisoning even when accidentally ingested. Therefore, you can leave it around children, cats and dogs.
Hoya Coronaria Problems & Troubleshooting
Your Hoya Coronaria may never experience pests. However, like all houseplants that’s something you can’t guarantee no matter what you do.
Therefore, the best way to prevent bugs form coming around is to keep the plant healthy and regular clean its leaves. Dust tends to attract these insects.
If they do come around, the most common problem will likely be mealybugs. Although spider mites, aphids and thrips can attack the plant as well.
If there’s a lot of moisture fungus gnats can appear as well.
So, regular inspection is important, especially under the leaves and near the nodes. That’s where they pests tend to hide.
You can use neem oil spray or horticultural oil to get rid of them. The earlier you treat them and the fewer the pests are the faster it is to eradicate them. You don’t want them to grow into a full-blown infestation.
Diseases are likewise a problem. But they’re more preventable. However, the most serious issue of all is root rot.
So, you want to do whatever it takes to avoid this.
This means avoiding excess moisture.
With leaves, avoid wetting the plant’s leaves and leaving them wet for long. As far as soil goes, don’t overwater the plant.