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Hoya Subcalva Care – Master Tutorial

Hoya Subcalva Care – Master Tutorial

(image credits, IG: verdant_vines)

Although this Hoya might have pretty uninteresting leaves, its most distinctive attribute is the blooms’ smell. You probably heard different accounts on the scent that Hoya flowers emmit, usually described as sweet, similar to chocolate, some even downright smelly like sweaty socks.

Well, the Hoya subcalvas’ flowers smell like grapefruit. Yes, the big red-fleshed citrus fruit. How awesome is that?

All you have to do is plant it in well-draining soil using a potting mix, gravel, orchid bark, perlite, and sand. Water it regularly, feed it twice a month with a good fertilizer, provide it with some humidity and a trellis to grab onto, and you can expect your home to smell like grapefruits once it blooms. Keep temperatures between 60°F and 95°F (15°C – 35°C).

If you are intrigued and want to find out more about this Papua New Guinea native plant’s care, keep reading. This is a detailed care guide with everything you need to know to take good care of a Hoya subcalva. 



Hoya Subcalva Care Guide



Your Hoya subcalva will need a classic hoya soil mix. Some people just mix a regular store-bought soil and cactus soil, but you can do better.

I suggest you take the time to nail the soil’s consistency so that you give your Hoya subcalva the best start possible.

In this case, since Hoyas are epiphytes, they need light, aerated, and chunky soil. Ideally, this would mean a mix that consists of one-third quality potting mix, one-third perlite, one fifth orchid bark, and one-fifth gravel or coarse sand.

Perlite is there to ensure airiness and moisture control, but it can float to the top of the pot over time since it is a very light material.

That is why your soil mix should include gravel since it won’t move, and it will break up the soil at the bottom of the pot.

The orchid bark has the essential role of being something the epiphytic roots can grab onto like they would in their natural habitat. 



Although Hoyas have semi-succulent leaves, you shouldn’t think they would do well in direct sunlight. Your Hoya subcalva will feel most at home in the shade with no direct sun.

Direct sunlight, especially the intense mid-day rays, can fry your leaves and cause sunburns. Sunburns are permanent, and the only thing you can do is cut the affected leaves off for aesthetic reasons.

Rooms that are too dark will also result in pale leaves, so try to find a happy medium. This should be an east or west-facing window and far enough from the glass to not be in direct sunlight. 



Watering shouldn’t be the nightmare all amateur houseplant collectors believe it to be. Although I know I have mentioned several times how hard it is to master, once you get to know your plant and its needs, it’s a piece of cake.

For Hoyas, this means that you should water them regularly, about once a week, but wait for the top couple of inches of soil to dry out before you do so.

Checking for moisture in such chunky soils can be a guessing game, but when in doubt, you can always grab a moisture meter and check. As you do so, inspect the soil and get in there with your fingers to understand what specific measurements mean/feel, and you can do it without a moisture meter in the future. 

I would also recommend using distilled or rainwater to water your Hoya subcalva. This way, you are making sure there is no mineral buildup in the soil, and you are avoiding crispy leaf tips. 



These are warmth-loving plants, and they should not be exposed to temperatures lower than 57°F (14°C). Ideally, they should be in a room with a temperature between 60°F and 95°F (15°C – 35°C).

Most importantly, you should try and keep the temperature relatively constant during the day. A slow temperature drop during the night is normal, but sudden cold drafts or bursts of air from a heater can do a lot of damage to your Hoya subcalva.

While they are not delicate plants, I would dare to call them finicky in the sense that they don’t like change and will almost immediately tell you so.

If you expose them to drafts, hot air, sudden temperature drops, or move them around the house a lot, expect them to drop leaves in protest. 



Although Hoyas are known to tolerate regular indoor humidities of around 45 to 55%, let me assure you that you can hardly expect the plant to thrive in such conditions.

If you want your Hoya subcalva to grow fast, be healthy, and put out blooms, you should do everything you can to provide it high humidity. The perfect humidity for these plants is between 70 and 80%.

This is easily achieved with a humidifier, but what should you do if you can’t afford a humidifier? Whether it is space issues or financial issues that prevent you from getting a humidifier, there are other things you can try to elevate the humidity in your home.

One example is the pebble tray, as it is the cheapest, simplest, and most space-saving option. It is simply a tray filled with pebbles or Leca topped with water that you can put your plant on.

The water level should be low enough so that it is not in contact with the pot, as its function is not to water the plant but rather evaporate and raise the humidity around your plant.

You can also put wet rags and water trays on your radiators for the same reason in the winter.



There is a couple of ways to go about fertilizing your Hoya. What I suggest is an organic fertilizer, which is not as harsh as synthetic ones.

You don’t have to dilute them, and there is less worry about fertilizer burn and mineral buildup. The chances of overfertilizing are also much smaller.

In this case, you should feed your plant every two weeks. 

If you don’t have any on hand and decide to feed your Hoya subcalva with a liquid synthetic fertilizer, this is also totally ok! Just dilute by half with water and pour it into the soil after watering once a month, and you are set. 

I would also like to mention some people like to give their Hoyas some bloom boosting fertilizer just as they are about to flower to maximize the flowering.

They report a pretty big difference in the number of blooms when they do so, and your Hoya will appreciate a perking up when it is busy putting out all those beautiful flower clusters. 



Hoyas are most commonly and easily propagated by cuttings. Lucky for you, if you want to share your Hoya subcalva or simply want more of them, the process is easy and straightforward, and Hoya cuttings usually have pretty high chances of success even without the addition of rooting hormones.

Here is the step by step process you can follow:

  • Choose a healthy vine to cut. You will need at least one node and two leaves for one successful cutting, so depending on the number of cuttings you want to propagate, choose a vine of appropriate length. Remember to pick vines that are neither too old nor very young and flowering. 
  • This cutting can then be put in water, sphagnum moss, or directly into the soil.
  • Wait for a couple of weeks for a couple of inches of well-developed roots to appear. While you do so, make sure your cuttings have enough indirect bright light, that they are warm and that they have enough humidity. You can enclose the cutting in a plastic bag to retain moisture, but remember to open and ventilate it regularly to prevent molding and rotting. 
  • Once the roots are there, you can repot your cuttings into regular soil. Keep the soil evenly moist initially, and wait for the plant to acclimate to the new medium. When you see it putting out new growth, that’s it; you have a new plant. 


An excellent tip to remember when propagating plants is to use disinfected shears to reduce the possibility of cross-contamination.

You should also never remove more than 30% of the mother plant, or else it might die. 

Finally, share the plant love and take your new plants to friends and family. It is a thoughtful gift that most people will enjoy, and costs you almost nothing!



The Hoya subcalva is a vining plant, and you can expect it to grow as long as 9’9″ (3m). Don’t let that size scare you if you don’t have a lot of space in your home.

Hoyas are most commonly grown on trellises so that you can wrap them around and about. They will need some support, so either opt for a trellis or a moss pole.  



I always choose a terracotta pot for all my Hoyas. Many Hoyas have already succumbed to overwatering in my house, so I take all possible precautions to prevent that.

A terracotta pot is perfect for that since terracotta (or clay) is an organic material that absorbs water. This means that it will absorb some excess water, if there is any.

I said some, not all, so don’t put all of your eggs in this basket and think you are safe.

It is not a must though and you can choose whatever container you want. Plastic nursery pots are also totally fine.

I recommend repotting your Hoyas every year or two, even if they are not root-bound. Many people forget repotting doesn’t necessarily mean increasing the size of the pot.

I like to repot all of my epiphytes yearly to give them a fresh change of soil, and they seem to appreciate that. 

Always be sure not to give your Hoya subcalva a pot that is too big. Too much soil around the roots will retain too much moisture and can lead to root rot.



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Common Problems with the Hoya subcalva

Hoyas are a pretty sweet treat for pests with their fleshy leaves and sweet blooms, so be prepared to fight off some invaders.

I always recommend regularly treating all of your plants with Neem oil, as it is a fantastic non-toxic feeding deterrent and fungicidal treatment, and it also makes the leaves extra shiny and luscious.

Here are the three most common ones and instructions on how to deal with them.



Mealybugs love Hoyas. You can spot them as tiny round cotton balls with legs that gather around the nodes, the leaves’ undersides, and basically wherever your plant’s flesh is softest.

Don’t be alarmed. These are some of the easiest insects to get rid of since they are slow and not very persistent.

Arm yourself with a q-tip dipped in alcohol and remove them one by one. The bug will die in contact with the alcohol.

Try to get as many as you can, and repeat this process every couple of days until they are completely gone. If you’ve got a more substantial infestation on your hands, it is ok to opt for an insecticidal soap treatment.

Just make sure you always wrap the bottom of your plant (The soil and root ball) in a plastic bag so that you don’t wet the soil too much, and it gets soggy. 


Powdery mildew

If you have been working on raising the humidity in your home but forgot about the importance of air circulation, you might find round white fuzzy spots on your Hoya subcalvas’ leaves.

This is powdery mildew, and it usually appears when there is standing water on the leaves, the soil is too wet, or the humidity is high, but the air is not moving.

To assess the situation, grab a piece of cloth dipped in a mix of 1 tablespoon of baking soda, ½ teaspoon of liquid soap, and a gallon of water.

Carefully wipe the spots off of the leaves and observe what is underneath. If left for a long time, the mildew can irreparably damage the tissue beneath, and such leaves should be removed.

If not, leave them and make sure you provide some more air circulation for your plant. Also, try watering it from below for a while.



Scale are bugs with a shell that stick to your plant’s stems and suck the sap from the plant to feed. This shell is a fantastic defense method, but unfortunately for you, it renders most insecticidal prays useless.

You have to go in with a scaping device like a blade or your nail, dislodge the bug, and then get it with a q-tip dipped in alcohol to kill it.

Make sure you are touching the soft insect and not just the shell.

Scale like to hide in all sorts of nooks and crevices, including the stem and roots below the soil. So be thorough and ready to repeat this process if you notice them again. 


Tips to keep your Hoya subcalva problem-free


  • Give it a well-draining and airy growing medium with perlite and orchid bark
  • Water it regularly, but let the top of the soil dry out between waterings
  • Feed it twice monthly with an organic fertilizer
  • Give it a terracotta pot and a trellis or pole to hang onto
  • Protect it from pests and diseases with regular Neem oil treatments


Frequently asked questions about the Hoya subcalva


Should I mist my Hoya subcalva?

I would recommend against misting Hoyas in general, as you are risking mold and fungal issues.


I just got my Hoya subcalva in the mail. What should I do next?

Inspect it, remove any dead or rotting leaves, and put it in a glass of water for a while before potting if it came with bare roots. Let it recuperate for a week or two and then repot if you deem necessary. 


Is the Hoya subcalva safe for pets and kids?

Hoyas are non-toxic to humans and animals, so they are the perfect plant for a family with kids and pets. 



To conclude, if you are looking for a fast-growing Hoya with great smelling blooms, you should look into getting a Hoya subcalva. Their care requirements are pretty comparable to most medium maintenance Hoyas, so they won’t be giving you too much unexpected trouble.

Water them regularly, but let the top of the soil dry between waterings, keep it in a decently bright spot, and feed it twice a month, and you are good to go.

If this Hoya is not quite what you were looking for and you are into some funky leaves, check out our article on the Hoya Krimson Queen; I think you are going to like it!

Hoya Krimson Princess Majestic Care Tips

Wednesday 25th of November 2020

[…] Leaves are 1.6-2 inches long (4-5 cm) and are thick and fleshy. Due to their waxy texture, Hoyas are commonly referred to as Wax plants.  […]