Why Are My Hoya Leaves Turning Yellow?

Hoya Leaves Turning Yellow

Hoya leaves turning yellow is something you should not take for granted. That’s because it can mean something very serious is happening to your plant.

That said, don’t panic either because sometimes, it may be nothing or something that is easily fixed.

Nevertheless, hoya yellow leaves warrant your attention. And because there are a few possible reasons for this, it is not a good idea to assume one or the other.

Instead, eliminate each potential cause until you get a final confirmation. Then fix the underlying issue.

Below, I’ll go through the different reasons which result in hoya leaves turning yellow.

I’ll also explain why each happens, how to diagnose it and finally how to treat them.

Why are My Hoya Leaves Turning Yellow?

Hoya leaves turning yellow is a sign of stress. And this stems from the plant not getting the care or requirements it needs.

The most common reason for hoya yellow leaves is too much water. This is often caused by overwatering or poorly draining soil.

The former has more to do with your watering schedule. As a result, overwatering happens when you add moisture too frequently.

The latter is associated to the kind of potting mix you use. Because it retains too much moisture, you end up with waterlogged soil.

Either way, the plant’s roots end up with wet feet which it hates. This will eventually cause your hoya’s leaves to turn yellow.

That said, it isn’t only too much moisture that causes yellow leaves. Other things than can lead to hoya leaves turning yellow are:

  • Temperature issues
  • Fertilizer problems
  • Too much light
  • Natural aging
  • Pests and disease

Below I’ll go through each of these causes and their corresponding solutions.

This way, you can diagnose the issue, check to confirm is one is actually the cause and subsequently fix the problem.

 

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Reasons Your Hoya has Yellow Leaves

The main reason that your hoya has yellow leaves is that it is not comfortable with its living environment.

Hoyas come from Southeast Asia and parts of Northern Australia. These regions have warm, humid climates as they are tropical and subtropical in nature.

As such, the plant is accustomed to these conditions.

Because you’re growing it out of its natural habitat, the goal is to try to keep its living conditions as close to what it is used to.

When it does not receive one aspect that it needs or desire, it will experience plant stress. And one of the symptoms of this is your hoya’s leaves turn yellow.

 

Overwatering

As mentioned, the most common reason why hoya leaves turn yellow is too much water. You can break this down into 2 causes:

  • Watering too frequently – this is a common mistake of new gardeners. Because most hoyas are epiphytes they don’t need to be watered daily. Instead, about once a week during the warmer months and about once every 2 weeks during the winter. To make sure, check the soil before you water. Only add more water if the top 1-2 inches of soil feels completely dry. Avoid doing so before that.
  • Soil has poor drainage – sometimes, even when your watering frequency is perfect, you can still end up with waterlogged soil. That’s because you’re not using the correct soil for the plant. Hoyas need well-draining soil that allows for good airflow. As such, dense, heavy or water retentive soils are no-no’s. And they will negate even a perfect watering schedule since the soil will hold too much water.

In either case, what happens is that your hoys roots end up standing in water. When there is too much water, the roots are not able to get the oxygen they need.

Roots need a balance of oxygen and water to stay healthy.

So, when they’re drowning in too much water, they cannot breathe. A good analogy of this is when you hold your breath underwater.

As long as you’re in the water, you can’t take in oxygen.

If you stay there too long, you run out of breath and end up suffocating in water.

That’s what happens to the roots with overwatering or waterlogged soil.

As a result, the chlorophyll (which is the substance that keeps leaves green) breaks down. When this happens your hoya’s leaves turn yellow. And many of them will do so at the same time.

You’ll also notice that yellowing leaves will start at the base with the lower leaves being affected first.

What’s worse is that the yellowing leaves is only a symptom (or an effect). And you have bigger problems to deal which are the roots themselves.

Therefore, it is very important to quickly take action the moment you see this.

First, check the soil, You can stick your finger into the soil to get a feel for it. Here, you’re looking for any substantial wetness. Wet, soggy, mucky soil are signs of overwatering.

Similarly, if it has been days since you watered and the soil still feels a bit wet, that means it is getting too much water.

Second, if you have a saucer or something under the pot to catch moisture, check if there’s water pooling there. You want to throw any water that collects there.

If you leave it there, the soil will eventually suck the moisture back up.

Third, if the soil is wet and mucky, or you have a bad suspicion, unpot the plant. Take the root ball out of the pot and check the roots for any rotting.

You can easily identify root rot as the once healthy, whitish roots will look black or brown. They’ll also be mushy instead of feeling firm. And they’ll have a stench to them.

If you see root rot, check how much of the roots have rotted.

Unfortunately, there comes a point where too much of the roots have rotted that the remaining soots cannot support the plant.

If only a small number of roots have been affected, prune the rotted roots. Then, repot the plant in fresh, dry well-draining soil. This will allow it to recover a bit.

Then when you start watering, do so lightly and only add more water once the soil feels dry.

 

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Improper Potting Soil/Mix

Above, I mentioned using the wrong potting mix.

Hoyas need soil with good drainage, aeration and don’t get compacted over time.

If you use clay or similar heavy potting mixes, what happens is that even if you have the perfect watering schedule, the soil will hold onto too much of the moisture and not allow it to drain.

So, the roots still end up standing in water.

Therefore, good drainage is very important.

A simple potting mix recipe you can use for your hoyas consists of:

  • 1 part cactus mix
  • 1 part orchid mix
  • 1 part perlite

You can likewise go with:

  • 1 part potting mix
  • 1 part orchid bark

If you prefer to use peat moss, you can opt for:

  • 2 parts peat moss
  • 1 part perlite or pumice

These combinations will hold enough moisture to keep the roots hydrated but ensure that excess water is quickly drained so the roots get wet feet.

 

Underwatering

Most hoyas have succulent-like leaves. Note that while they are not true succulents, they have leaves that are thick (which are similar to those of succulent plants).

This allows them to store moisture in their foliage, which in turn lets them tolerate dry periods (and some drought).

However, past a certain point, they will succumb to dehydration as well.

When this happens, you’ll see your hoya leaves turn yellow and become crispy.

As such, avoid letting the soil go completely dry for extended periods of time.

That said, underwatering is a less common cause of yellow leaves in hoya plants. Therefore, it is one of the later things on your checklist when trying to diagnose the issue.

And because overwatering can likewise be the cause, it is very important to check the soil before takking any action.

If the soil is very wet, it is likely overwatering. Therefore, don’t add more water.

In contrast, fi the soil feels very dry, it is likely underwatering. Therefore, you can add water.

 

Old Leaves

Now, I’m going to jump the gun here a bit and go with a non-issue.

What I mean to say is that just because your hoya has yellow leaves doe not mean it has a problem.

Older leaves (which are the lower leaves) will turn yellow and the plant will shed these leaves to make way for new, younger foliage.

That’s just the natural life cycles of the plant.

Therefore, if this is the case, then you have nothing to worry about.

However, when this happens, only a few leaves at a time will turn yellow. You should not see many leaves turning at the same time or keep seeing green ones turn yellow.

If the latter is happening, it means there’s an issue.

 

Too Much or Too Little Light

With that out of the way, let’s not get back to other potential causes of hoya yellow leaves.

After watering issues, light is next common cause for yellow leaves in hoya plants.

This is probably the easiest to diagnose since all you need to do it take at look at how much light the plant is getting.

In general, hoyas are what you call gap plants. in the wild, they take advantage of gaps above them where there are not trees or plants. Therefore, light is able to reach the ground in these gap areas in the forest.

That’s where the hoyas tend to grow.

That said, the light reaching the ground in these locations are still somewhat dappled.

This is why hoyas have poor tolerance to strong, direct sunlight.

Instead, they thrive in bright, indirect, filtered or dappled light indoors. And do so in partial shade outdoors.

So, too much or too little light can result in hoya leaves turning yellow.

Too Much Light

Of the two, the more common issue is usually too much light. if you leave the plant under direct sunlight for more than 2 or so hours a day its leaves can eventually turn yellow or brown.

With repeated or long exposure, foliage can eventually get sunburn marks and brown tips or edges.

As such, avoid mid-day direct sunlight as well as summer sun.

It can tolerate morning sun before 10:30 a.m. and late after sun after 4:00 p.m.

When hoyas get too much light, their leaves will eventually fade in color. The reason is that chlorophyll is what keeps the leaves green. It is also what absorbs light for the plant to use in photosynthesis.

Therefore, when there’s a lot of excess light, the plant will adjust seeing that it does not need as much chloroplasts (where chlorophyll is found).

And as the plant adjusts this, the leaves also lose their green color and turn more yellow.

 

Lack of Light

On the other hand, yellow leaves is a later stage symptom of lack of light.

Again, what happens here is the plant adjusting to the amount of light.

However, this time, because it senses there isn’t enough light. it will turn more green to try to absorb as much light as it can from the insufficient light source.

So initially, the leaves will turn green. This is why if you have variegated hoyas, they will lose their colored variegations and turn green.

This is a sign it is sacrificing its beauty for survival.

If you leave the plant where it is, it will eventually be unable to sustain itself due to the insufficient lighting. This is when the older, lower leaves will turn yellow and then start dropping.

Because, the plant relies on light to fuel its photosynthesis, lack of light also causes it to grow slower and produce fewer, smaller foliage as well.

Finally, there’s also an added risk to too little light in that soil takes much longer to dry compared to a well-let location. This puts its at higher risk of overwatering (which can eventually cause yellowing leaves as well).

 

Temperature Issues

Hoyas are tropical plants. That’s because of where they come from. Both Southeast Asia and Northern Australia feature warm to hot temperatures.

But thanks to the forest canopy, it gets some reprieve from too much heat.

Nevertheless, hoyas still enjoy 65 to 80 degrees Fahrenheit temperatures best. They can tolerate 95 degrees heat but only go down to 50 degrees on the cold side.

Therefore, you want to be more wary of the cold.

When kept in lower temperatures, your hoya’s leaves wilt run yellow, with the youngest (newer) and oldest leaves being more prone to this discoloration.

So, avoid keeping the plant near air conditioners or drafty windows. Also, bring in back indoors once the weather gets cooler around fall. It won’t be able to withstand winter frost.

On the other hand, while the plant can tolerate heat better, it is will likewise experience temperature stress if it gets too hot.

The result will be yellow leaves that are dry. You’ll also see brown leaf edges and tips.

Too much heat can also lead to underwatering.

Therefore, just like light, make sure to check on the plant as the seasons change. Both lighting and temperature will significantly change when summer turns to fall then winter and back to spring again.

 

Nutrient Deficiency

Another cause of hoya yellow leaves is nutrient deficiency. This is why it is important to feed your hoya.

While they don’t need a lot of fertilizer (they are generally light feeders), they still need nutrients in order to avoid any deficiencies.

Here, yellow hoya leaves are often caused by lack of nitrogen in their diet.

Hoyas ae are foliage plants. As such, they need nitrogen as this is not only an essential nutrient for plants, it is also what promotes foliage development.

As such, use a balanced liquid houseplant fertilizer diluted to half strength during spring and summer.

 

Acclimation to New Environment

New environments can cause a hoya’s leaves to turn yellow as well. This can happen as it adjusts to its new living conditions.

As such, it may occur after you take the plant home from the shop.

However, it this persist past the first 4 or so weeks, it is a sign that it is struggling with the new environment.

When this happens, you’ll see its older leaves turn yellow. Later on, they will drop.

Make sure to check everything again starting from lighting as this will usually be the main cause when the plant is getting acclimated.

Check to see that the plant is getting sufficient lighting and not too much direct sunlight.

 

Pests

Hoyas are not overly susceptible to pests. However, they do attract sap sucking insects. In part this is because of their semi-succulent foliage which the pests like.

As such, your hoya can experience mealybugs, spider mites, scale, aphids and thrips.

Since they steal sap from your plant, they’re essentially robbing it of nutrients and moisture (which is what’s in sap).

So, you’ll notice yellow blotches or patterns in the leaves. Since pests are small, the yellow sections you’ll see are also scattered based on where they fed.

However, as they grow in number and you reach a point of pest infestation, they are capable of turning entire leaves yellow.

Therefore, make sure to check the leaves regularly for pests.

 

Diseases

Certain diseases can turn hoya leaves yellow. However, the kind of marks, patterns, stripes, spots and other abnormalities will depend on what disease ails the plant.

In general, hoyas are quite resistant to disease because their leaves have an extra layer of protection. However, they are by no means immune.

This is especially true when the plant is overwatered. In this state, it becomes more susceptible to diseases.

Therefore, make sure to avoid overwatering and use the right kind of soil to drain excess moisture.

 

How Do You Save a Yellow Hoya?

The only way to save a yellow hoya is to fix the underlying cause of the problem.

This means going through the possible list of causes above to eliminate them one by one until you have a diagnosis.

Then use the fix I’ve listed above to fix the issue.

Once the cause is resolved, the stress applied on the plant will go away. And so will the yellow leaves. At least new yellow leaves will not happen anymore.

Unfortunately, leaves that have turned yellow will not become green again. Therefore, the solution will be to prune them or allow them to eventually drop.

The good news is that new leaves should be green and healthy now that the problem has been resolved.