Hoya Subcalva Care InfographicThe Hoya subcalva scent is quite unique as this plant smells like grapefruits. You might think its leaves look a bit boring, but the blooms it produces are out of this world.

We have curated and compiled this extensive guide on how to grow the best subcalva Hoyas ever. Carry on reading to find cool tips and tricks tested over time.

What Is Hoya Subcalva?

Hoya subcalva is a gorgeous flowering plant originating from Papua New Guinea. This Hoya blooms later in the year during the October to April period, unline other Hoyas. Additionally, each flower stem produces at least 10 to 12 flowers each, which give a very nice smell.

Hoya Subcalva Care

Since this hoya grows in a diverging way, you can put your Hoya on a trellis, because hoyas tend to have a creeping vine-like growth habit. They will hold on to any support that you provide them with. Have them grow around a trellis for a beautiful decorative effect. There’s so much more of the care guide written below, step by step we will lead you through them.

– Light Requirements

Just because Hoyas are semi-succulent doesn’t mean they can tolerate direct sunlight. In fact, they get easily sunburnt with their leaf edges curling and turning a pale brown.

That is why this vine is safely grown indoors within your living space. Put them in a place that is adequately lit by sunshine. Any spot within such a room will do, but it shouldn’t necessarily be near a window. You can also use the training vine of this subclavian to frame the windows. Just take care that it is not a window towards the south.

Not everyone is lucky to have their living space lit brightly by good sunshine. This shouldn’t stop you from growing a Hoya indoors. There are so many options available regarding artificial grow lights for indoor plants.

Personally, we recommend you buy LED lights compared to fluorescent lights.  Put these lights preferably immediately overhead the plant. Put the lights at a safe distance to keep the plant from overheating.

To make your Hoyas more splash, use artificial grow lights. Use one with wavelengths of just the right fluorescent light, such as agromax pure PAR. Some hoya varieties have a splash, such as a hoya odorata and hoya undulata.

Hoya flowers shaped like star – Water Requirements

Subcalva is a plant that likes evenly moist soil. However, the top one to two inches of this soil should be allowed to dry before you water it next. Ensure that you make it a habit to always check the moisture level of the soil before watering.

This will literally solve 90 percent of all your watering problems. A moisture meter will give you the most accurate reading of the topsoil’s dryness. You can use your finger to poke around the topsoil and feel if it is dry enough.

Distilled water is what is ideal for the health of this plant, because using ordinary tap water might be convenient, but it only harms the plant in the long term. Distilled water is the safest, although it might be a hassle to buy and use it all the time. If you insist on tap water, at least filter it and leave it exposed to air overnight. This makes it a little bit safer.

With prolonged use of tap water, chemicals and toxins will accumulate in the soil. Nutrient uptake by the roots will be seriously impaired. You might even see crystals precipitated around leaf edges, causing burns.

The reverse watering technique is an important technique that helps if the soil has been neglected and left to dry for long. To revive the soil and the plant again, it’s best if they are watered from the bottom. Look at the underside of the pot at the drainage hole. If they appear blocked, open them again using a screwdriver.

Put your dried subcalva plant in a bucket. Then fill this bucket with water halfway to the pot’s length. Leave the pot in this position for about 10 to 15 minutes. Touch your topsoil to see if it feels moist after this time.  If it does, lift the pot and place it on a water collection saucer.

This means the soil has been watered from the bottom to the top. Drain the saucer when the soil has drained its extra water into the collection saucer. From now on, take great care of your plant’s water needs.

– Soil Requirements

Having in mind that this plant grows on top of natural rocks, traditional potting soil isn’t the most suitable. This plant likes chunky and rocky soil with plenty of spaces for the roots to move around.

Start by taking some ordinary cactus mix and adding chunky pieces of wood bark and charcoal in them. Add in a fistful of perlite for some micro-level aeration. Cover the soil with an inch or two thick layers of mulch to prevent the top layer from drying faster than helpful.

– Temperature Requirements

Subcalva hoyas are warm growing plants all year long. Their beloved temperature range is 60 to 95 degrees Fahrenheit. The temperature under 55 degrees Fahrenheit is particularly unhealthy for it.

When growing this plant indoors, you will be able to maintain these temperatures pretty easily. A slight change in temperature from day to night is okay, but sudden drops such as cold air drafts can also be damaging.

Your plant will exhibit signs to tell you if it is suffering from low temperatures. Its leaves will start drooping down. In extreme cases, it even starts dropping leaves off altogether. To save it from dying, move the plant to a warmer spot immediately.

– Humidity Requirements

This plant needs 60 to 70 percent humidity no matter what time of the year to truly thrive. Even at normal household humidity levels of 45 to 50 percent, this plant will continue to survive. However, it won’t thrive and bloom as expected of a Hoya. 

There are multiple ways to increase humidity around the plant artificially. You can choose the method that you like yourself. Humidifiers can take away most of your humidity-related issues as you must plug the humidifier into a socket, which will maintain the same humidity levels for your plant. It will save you from any further hassle in this regard.

You will not have to turn the device on and off with automatic humidifiers. It will automatically sense when the desired levels are reached and shut down. Then, when the levels start dropping, it starts back again. The problem with a humidifier is that it is pricey to buy and expensive to run constantly. If you find it too costly, more economical methods are available.

A pebble tray might not be able to maintain the same levels of humidity; nonetheless, they contribute about 15 to 20 percent to air moisture. Most take care that the water in the tray is not touching the pot’s underside.

This is also one of the top reasons the soil gets overwatered. You will have to change the water in the tray every week. This is to prevent insects and mosquitoes from laying their eggs there.

– Fertilizing Requirements

This plant needs to be fertilized regularly from early spring till late summer. Any regular and well-balanced chemical fertilizer can be used, although a natural fertilizer would be much safer. Just before bloom, give a phosphorus-rich fertilizer to the soil. After this, you will feel a marked difference in the quality and quantity of the blooms.

Natural compost is super safe for your plant, so you can give it to the plant every second week. It does not need to be diluted at all. You can go for homemade compost or use worm castings. If you are not into composting, worry not because you can easily obtain a natural fertilizer from the market.

Keep in mind that liquid fertilizer will provide your soil with an immediate boost of nutrients. However, it does need to be diluted by adding an equal volume of water before use. With a chemical fertilizer, you have to feed every month instead of twice a month. It’s best to use a fertilizer from a good manufacturer. Don’t forget the golden rule: feed the soil, not the plant!

– Pruning

Pruning will keep your Hoya vine from growing unimpeded and wildly. It will also keep the plant in the shape you want it to. The best time to prune your subcalva is during the springtime period. period

Pruning also involves plucking off old, withered, or discolored leaves. The nutrients will be better transported off to newer and younger leaves. Check to see if any pests are hiding or lurking under the leaves. Be quick while cutting off a stem or a leaf during pruning. An incision at 45 degrees angle will help promote better growth at the cut end.


You can grow multiple copies of this gorgeous plant to increase its population in your house. There are several methods to propagate this Hoya. Propagating through vine cutting is the method of hoya propagation that produces the best results. Choose your cutting wisely. 

The vine you take should neither be too old nor too young. It should be healthy with no signs or spots of pests or diseases. Cut a four to five inches long piece of this vine at an angle of 45 degrees. Your cut piece should have two leaves and at least one node.

Allow this cutting to dry and then form calluses at the incised end. This would take at most one to two days in an air-tight container. When planting in moss, make sure that it is kept evenly moist.

When it becomes dry, sprinkle water on it, so it doesn’t become runny. When planting in water, place half of the cutting in water so the leaves are above water and the rest of the stem is submerged.

Place your growth media in an indirectly brightly lit spot. To increase humidity to around 60 percent, you can cover the lid of the water container. A new plant will sprout from the cutting in three to four weeks.

You need to give them time to grow more without disturbing them. After one to two weeks, carefully take your rooted cutting out. It is now time to plant it within well-draining hoya soil.


Subcalva is not a very problematic houseplant but can be sensitive when not taken care of properly. Some basic problems you might have to deal with are yellowing of the leaves, pests, or rot roots due to overwatering.

– Yellow Leaves

Yellow leaves on a hoya ruin the whole look of this plant. First of all, check the light conditions around the plant. If it is placed under direct sunlight anywhere, this might be the foremost cause. If the lighting is suitable, your watering regime might be the problem. Both under and overwatering can produce chlorosis in leaves.

Check the condition of your leaves by the look and feel. If they appear wrinkly, shriveled, and droopy, underwatering has caused this. On touch, too, the leaves feel dry and papery thin.

They will have lost the plumpness characteristic of them. You will notice that the soil is also dry all the way through. Such a plant will have to be reversed and watered immediately. Then follow this up with a watering schedule that you strictly adhere to.

If the yellow leaves look swollen and drop under the weight, then overwatering is your problem. When you touch them, they feel mushy and fragile. The soil will be moist up to the topsoil. It might even be proper running with water. Remember that you must stop watering immediately and place the pot somewhere warm and sunny to dry the soil quickly.

– Root Rot

If the soil is overwatered persistently, it does inevitably cause the roots to become rotten. These roots get infected by a superimposed fungal infection which then spreads to the entire plant.

The leaves develop irregular, small-sized, and yellow spots that are moist and water-filled. These spots quickly turn black and also break down in the center. If root rot is not treated immediately, your subclavian will soon die.

If you want to save your plant from root rot, hold your hats because it needs time and effort. Using a rake, you will have to take the plant out of the soil properly. Then dry the plant using plenty of absorbent paper.

Spray the plant, the soil, and the pot generously with a potent liquid copper fertilizer. Repot the plant again but keep in mind that despite all this, the plant still might not survive.

– Pests

For plants kept mostly indoors, sap-eating pests are more common than leaf-chewing pests. These pests make tiny punctures in the leaves and suck sap from them. Over time your plant becomes malnutrition severely.

Some of these pests can be seen, such as mealybugs, spider mites, or scale insects. Others, like aphids, cannot even be seen because they are so tiny.

Don’t worry. You can easily catch a pest infestation by certain telltale signs. First of all, the plant will lose its vigor and appear unwell. Yellow irregular or round spots will develop on the leaves.

These will be dry spots as compared to wet spots of rot. Some of the newer leaves might turn partially or completely yellow due to a lack of nutrients. The growth of new leaves will be much less. They will be small in size and will not look very healthy.

To kill pests and save your Hoya plant, you must first wash it. Use a potent insecticidal soap and wash the undersides with special care. This is where most of the pests and their larvae will be present. 

When the plant is dry, apply a few drops of neem oil over the spots on the leaves. Some pests leave a sticky residue on the leaf surface that traps mold. Neem oil will remove this sooty mold too. Additionally, neem oil will have to be applied almost every week for a month to make sure that the infestation is truly over.


– Can Hoya Subcalva Be Propagated Through Seeds?

Of course, like all plants, Hoya can also be grown using seeds. This method is not for beginners, we must warn you. It takes expertise, time, and effort from the gardener.

If ordering seeds online, use a seller with the best reviews. It is best just to go to a trusted nursery within your community. Soak the seeds in clean water for eight hours right before sowing them. Spread sphagnum moss in an even layer over a seedling tray. 

Then start putting these seeds one by one into the moss. Gently push each seed only about a quarter inch into the moss. Put this tray in a transparent plastic bag and place it in a bright spot. Every few days, take the tray out to let fresh air in. If the moss seems to have dried, sprinkle water over it to keep it moist.

Depending on how successful your propagation goes, the seeds will germinate in four to five weeks. Pull the tray out of the plastic bag but let the plantlet stay for an entire month. Afterward, take each plantlet out gently and place it in its own pot.

– How Can I Make My Hoyas Bushy?

In order to make your hoyas bushier, the key is to fertilize it directly in the soil, in the months from spring to fall. This is the time when the hoya is most active to grow and to prosper in its state.

Furthermore, what is key to remember is that the plant will look fuller and more bushier when you cut off the longer stems, which would give it better foliage and fuller look.


Before ending our guide, let us reiterate some key takeaway points. Here is a sum-up of what we covered:

  • Grow this plant in the chunkiest type of soil you can make. Add perlite, charcoal, and tree bark to loosen it up.
  • Maintain a steady state of high temperature and humidity all year round.
  • They need a largely chunky and aerated soil to grow their roots in.
  • Always disinfect your cutting instruments before pruning each spring.
  • This Hoya produces its grapefruit scented blooms later in the year.

Subclavian is a Hoya with round bunches of flowers that smell like a grapefruit. This is a plant that requires time and effort on your part but trusts us; the blooms will be worth it.

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