Hoya Subcalva Growing & Caring Tips

Last Updated on April 14, 2022 by Admin

The Hoya Subcalva is a climbing plant that is known for both its beautiful deep green leaves and stunning flowers.

It is a climber and will appreciate something to go up on like a trellis.

It produces many leaves which makes it beautiful if you let it get bushy. Of course, its show-stoppers are its pink or purple flowers that emit a sweet, citrus fragrance.

How do you care fro Hoya Subcalva? Supply the plant with bright, indirect light to encourage blooming. It likes warm weather and can go dormant in cold winters.

Give it high humidity if possible, to optimize growth and improve its chances of flowering. Don’t overwater it as it is epiphytic and prone to root rot.

Hoya Subcalva Plant Care

Light Requirements

The Hoya Subcalva prefers indirect to direct sunlight indoors and partial shade to full sun outdoors. This is very important to keep in mind since many people refer to hoyas as succulents.

However, they are not the same.

And you should not take care of your hoya plants like you would succulents.

An example of this is lighting.

While the Hoya Subcalva has succulent-like leaves, it needs medium to bright indirect light to thrive. Avoid direct sunlight especially during mid-day as the sun’s rays are too intense.

This will result in leaf discoloration and possibly burnt leaves.

In contrast, succulents love direct sun. They also thrive in full sun outdoors.

If you give your Hoya Subcalva this kind of lighting condition, it will survive. But its leaves will turn all ugly and brown forcing you to prune them.

On the other hand, you also want to be wary to low light.

Again, the plant can survive in this condition. But its growth will slow down.

More importantly, if there is insufficient light, you’ll see its green leaves turn pale in color. Also, the Hoya Subcalva is unlikely to bloom in low light.

Therefore, you’ll miss out on its beautiful, fragrant flowers.

For this reason, an east or west facing location is ideal for the plant. In the former you can keep it near the window as the morning sun is gentle.

But in the latter, place it a few feet from the window to avoid the afternoon rays of the sun.



The Hoya Subcalva will grow optimally in warm environments. Ideally, keep it in temperatures between 60 and 95 degrees Fahrenheit.

This is a wide tolerance range which makes it easy to care for especially indoors.

And you’ll probably notice that it can tolerate hot climates as well without any problems.

The reason for its is that it is native the tropical regions. As such, the weather there usually only has 2 seasons, warm to hot or rainy.

There are no winters in the tropics so the plant has poor tolerance to the cold.

As such, try to keep it away from anything colder than 55 degrees Fahrenheit.

Below this temperature, it will struggle, beginning with slower growth. And the longer it is left there, the more problems it will experience especially if the temperature continues to drop.

This can cause yellow leaves and leaf drop. Eventually it can kill the plant as well.

This is why you want to make sure to bring the plant indoors before winter arrives.

The only exception to this is in USDA Hardiness Zones 9 to 11. The plant loves it in these regions because the weather is consistently warm all year round. Additionally, there is no snow or freezing temperature.

So, you can leave it outdoors from November to March with no risk of cold damage or death.



For optimal growth, give the Hoya Subcalva humidity of 60% to 70%. I know that this is on the high side. But it is the best way to achieve optimal growth.

High humidity allows the plant to grow faster, produce more vibrant foliage and also bloom.

That said, it will tolerate 50% humidity as well.

So, at the very least, try to target this threshold.

Note that depending on where you live, you may or may not need to worry about humidity.

That’s because certain areas are naturally more humid that others.

For example, tropical and subtropical locations. Also, anywhere near the coast or if you live near a lack. Large bodies of water not only help regulate the heat the and cold but also increase humidity.

On the other hand, desert or desert-like areas have dry air.

This is why Nevada, New Mexico and Arizona rank among the three lowest humidity states in the country.

If you live in areas like these, you may need to increase humidity around the plant to keep it happy.

One way to do this is to use a humidifier. You can likewise mist the plant regularly or move it to the bathroom.

Another option is to group it with other houseplants.

But my favorite methods are either using a pebble tray or humidity tray. Both work the same way but just use different setups.




How Often to Water Hoya Subcalva

Like other hoya varieties, the Subcalva needs regular watering. It likes moist soil. And on average it does best with once a week watering.

That said, be careful with overwatering the plant.

That’s because it stores moisture in its semi-succulent leaves. Additionally, the plant is an epiphyte which means that its roots prefer getting a lot of air.

When they do get wet, the roots tend to dry very quickly since they’re not buried in soil. Instead, they’re clinging onto trees which lets them receive plenty of light and good airflow.

Therefore, the plant is susceptible to too much water.

So, avoid watering too frequently or when it isn’t time yet?

How to know when to water the Hoya Subcalva?

Feel the soil.

Doing this once a week or every 3-4 days will give you a good feel of how fast or slow it dries.

More importantly, only water the plant when the top 1-2 inches of soil has completely dried. You can stick your index finger into the soil to feel for moisture.

Alternatively, you can get a moisture meter and use that to know when to water the plant.

The important thing is to allow part of the soil to dry out first before adding more water. This prevents the roots from sitting in too much water for very long periods of time.

That said, avoid letting the soil go completely dry as well.


Hoya Subcalva Potting Soil

The best potting soil for the Hoya Subcalva is light, well-draining and has good aeration. Again, this stems from its epiphytic roots.

Good drainage ensures that the soil quickly gets rid of excess water. At the same time the porous nature of the soil mix allows air to easily get to the roots to allow them to breathe.

Avoid using heavy soils or those that can get compacted. These will cause overwatering or waterlogging problems.

In fact, they will negate your watering schedule.

So, even if you water the plant perfectly, the heavy soil will retain much of the moisture that the roots end up drowning in liquid anyways.

Fortunately, it is easy to create the perfect potting soil for the Hoya Subcalva. And there are many ways to do it.

A simple soil mix recipe that works is:

  • 2 parts peat moss
  • 1 part perlite

If you have potting mix at home already, you can use that instead.

  • 1 part potting soil
  • 1 part perlite or pumice

On the other hand, if you prefer getting bagged potting soil from the store instead, then ask for African Violet soil.

This will work well.



For optimal growth, the Hoya Subcalva needs nutrient supplementation. Although it will survive without fertilizer, I do suggest using one.

That’s because it will help the plant grow faster and produce more foliage. Additionally, it can help increase the changes of flowering as well.

Ideally, use an organic fertilizer.

These are more expensive. And you get less for your money. But they also don’t leave as much excess salts and minerals that can harm the plant.

Unfortunately, the added cost and much lower bang for its buck means that majority of gardeners use synthetic fertilizers.

This is not necessarily a bad thing.

But you need to watch out for over fertilizing more. That’s because synthetics leave more residue in the soil.

If you go with this, choose a balanced, liquid fertilizer and dilute it to half strength each application. This will lessen the salt and mineral build up in the soil.

Only feed the plant once a month during spring and summer.

It does not need feeding in fall or winter.

In addition to this, it is good practice to flush the soil once every 2 or so months to get rid of the excess salts in the soil.


Flowers / Blooms

The Hoya Subcalva is known not only for its beautiful leaves but also its stunning, fragrant flowers. With proper care, you’ll likely see it bloom during the warmer months of the year.

Its flowers vary in color.

I’ve seen some producing small pink flowers with red centers. There are likewise other varieties that develop light purple flowers with white centers.

Either way, these are all beautiful.

And while small, they grow in clusters giving you 20 or more small blooms forming a sphere-like shape that is about the size of your palm.

The Hoya Subcalva’s flowers also have a lovely citrus-like aroma that makes them alluring.



The Hoya Subcalva is a climber, although you can let its long stems trail down a hanging basket as well.

In most cases, you’ll see growers set up a trellis or some kind of shaped wiring above their pots to allow the plant to follow the structure.

This allows the plant to grow faster and produce more beautiful foliage.

That’s because it feels more at home as that’s the way it grows in the jungle.

That said, the Hoya Subcalva will grow as long as 10 feet tall if you let it. It will have many vines filled with dark green leaves.

This means that you will need to prune it every now and then.

How often will depend on how neat and how long you want to let the plant grow.


How to Propagate Hoya Subcalva

The most poplar way of propagating the Hoya Subcalva is from stem cuttings.

This works well because the plant has lots of stems. And it roots well with this method as well.

Not to mention that it is easy to do at home and does not require any special tools. Best of all it is free!

And you can propagate more than one new plant at a time.

Here’s how to propagate the Hoya Subcalva from stem cuttings.

The most important step is to choose the right cuttings. These need to be healthy. And each cutting should have at least 1-2 nodes on it and several leaves.

Don’t choose stems with flowers.

To cut the stems, take a pair or scissors or pruning shears. Then sterilize the blades with rubbing alcohol or hydrogen peroxide.

When ready, cut the stem just below a node.

Remove the lower leaves but keep the upper ones. You’ll want to keep these since they’ll help with photosynthesis which will let the new plant grow faster.

Next, get a pot and fill it with well-draining soil.

Then plant the cuttings into the soil with the nodes buried under the surface.

You’ll need to water the plant each time the soil dries. But be careful not to overwater it or leave the soil soggy. This will destroy the cuttings.

Leave the pot in a well-lit location with no direct sunlight. If there isn’t a lot of humidity there, you can cover the pot with a plastic bag to increase humidity.

It will take a few weeks (usually 3 to 6 weeks) for the roots to develop and begin to establish themselves in the soil.

In about another month or so, shoots will begin to show up.


How to Repot or Transplant Hoya Subcalva

Like other container plants, there will come a point where you’ll need to repot the plant.

But don’t be in a hurry here.

It usually takes 2 to 4 years before you need to repot the Hoya Subcalva. I also have some friends who’ve kept their hoyas in the same container for 5 to 10 years.

That’s because they like being root bound.

In fact, a root bound hoya is more likely to flower. This is one reason you’ll see many gardeners hold off on repotting.

That said, at some point the plant will begin to struggle. Also, you’ll notice the soil will dry very quickly soon after you water.

When this happens, it is time to repot.

Only go up one pot size at a time when choosing the new container. If you have issues with overwatering, use a terracotta or clay pot.

These are more porous. Thus, they allow water to seep out reducing the risk of overwatering.

Don’t forget to replace the soil as well. Old soil is spend, can get compacted and depleted of minerals. So, refresh it with new, well-draining potting mix.


Is It Toxic/Poisonous to Humans, Cats & Dogs

No, the Hoya Subcalva is not toxic. This makes it safe to keep around the house, backyard or patio especially if you have kids, cats or dogs.

You can have the peace of mind that there is no risk of poisons to your children or pets.


Hoya Subcalva Problems & Troubleshooting


Mealybugs, scale and mites are common pest that will come to attack the plant. These are attracted to its thick, succulent-like leaves.

Therefore, it is important to regularly check the plant for any signs of bugs.

Make sure you inspect the undersides of the leaves since the insects like to hide there.

If you do spot any pests, immediately isolate the plant and start treatment.

I usually like to spray them off using a hose or shower head. This is a quick way to get rid of a lot of pests almost immediately.

It does take 2 to 5 times with a few days in between each spraying to get rid of them. So, you do need to repeat until all the bugs are gone.

Avoid leaving any insects be it adults, larvae or eggs.

These will just grow and start the cycle over again.

Other options that work well include insecticidal soap and neem oil.



Bacterial and fungal infections usually are the first things that come to mind when taking about diseases. And these can be dangerous.

But don’t forget about root rot.

All of these are damaging to the plant.

And some can eventually kill your as well.

Since overwatering is the number cause of all these issues, it is very important to watch out for this.

Note that overwatering does not only involve the soil but also the leaves. So, let the soil dry between waterings. And don’t water the plant such that all the leaves end up very wet.

Instead, water directly onto the soil.

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