Hoya leaves turning yellow can be due to several different things.
In my experience, the most common reasons are related to watering (either too much or too little). In other cases, the leaves can turn yellow due to sunlight problems, issues with the soil or several other factors.
Let’s get straight into the list so you can quickly find out what is responsible for the leaves on your hoya turning yellow and what you can do to fix it.
- 9 Reasons For Hoya Leaves Turning Yellow With Solutions
- What Should Healthy Hoya Leaves Look Like?
- In Summary
9 Reasons For Hoya Leaves Turning Yellow With Solutions
Here are the 9 most common reasons for hoya leaves turning yellow from my experience of keeping hoyas for several years, along with how to solve each specific problem.
Overwatering has to be the most common reason for not just hoya leaves turning yellow, but pretty much every houseplant.
Overwatering is so common because a lot of people, especially those new to plant keeping, like to think that you need to water plants regularly to get them to grow. While this can be the case during the summer, most houseplants actually don’t need to be watered frequently.
For example, I water my hoya once per month during the winter and about 2 or 3 times per month during the summer and that’s it. Anyway, that’s enough about my own experience with hoyas.
To determine if your hoya is overwatered the first thing to do is inspect the leaves. If overwatered the leaves will turn yellow and wilt, and it’s very likely that the soil will be saturated with water.
If you’ve overwatered your hoya then there are usually two outcomes:
- In mild cases, you just need to stop watering and let the plant absorb the rest of the water.
- In severe cases, root rot will be affecting the roots and cause some serious damage. You’ll need to remove the soil, trim the roots and repot, and even then it is not guaranteed that your hoya will survive.
You should really only water your hoya when the top two inches of soil are dry – this applies to underwatering as well.
Underwatering is not as common as overwatering, but it can still happen and it does cause the leaves to turn yellow.
The difference here is that the leaves will turn crispy, and they also tend to turn brown more quickly as well.
Underwatering is really easy to deal with – all you need to do is water the soil generously and let any affected leaves drop off naturally.
If your soil is well-draining (which it should be) you can place your hoya in a sink or bathtub and let the water run through the soil.
3. Sun Scorch
Although there are several varieties of hoya that can be sun stressed to produce brightly colored leaves, most people don’t do it properly or instead simply place their hoyas into areas with too much direct sunlight.
If your hoya hasn’t adapted to direct sunlight the leaves can be scorched easily. This will appear as uneven spots or blotches on the leaves that are brown in the centre with yellow banding around.
Sun scorch isn’t a very serious issue as it usually only affects a couple of leaves before you’ll realise that something is wrong.
Affected leaves will naturally fall off, and you just need to move your hoya somewhere with less direct sunlight. Make sure the soil is watered properly as well, as underwatering is quite common if the plant was placed in direct sunlight.
4. Low Nutrients
Hoya leaves will turn yellow if they aren’t provided with the right type and amount of nutrients.
Nitrogen specifically is required to supplement foliage growth and supports photosynthesis on the leaves. Without enough nitrogen, the leaves will turn yellow over time.
There are also other nutrients that can cause yellowing leaves, such as a lack of either magnesium or sulfur.
Most of the time your soil mix should be enough, but I would recommend supplementing with fertilizer as well.
My recommendation is to use 2-1-2 or 3-1-2 for most of the year to supplement leaf growth, and then use a higher phosphorus concentration during the blooming season (5-10-5) at a diluted concentration.
In the winter I personally don’t fertilize my hoyas, but it depends on the climate where you live. If you still experience good growth during this time then don’t hesitate to fertilize.
This can quite obviously cause the leaves to turn yellow; sap is nutrient rich and helps boost photosynthesis, and the physical damage from the feeding process itself will affect the leaves.
Pests can be tricky to deal with, and prevention is always the best thing to get right in the first place.
Isolate new plants for a week or two before you let them near your other plants and regularly check for signs of pests.
For moderate infestations, you can try to rinse the leaves with water to remove any pests. Insecticidal soap would be the next call of action, as this kills pests and is very effective at dealing with larger infestations.
Root rot is one of many diseases that can affect hoyas, some others include leaf spot, botrytis and powdery mildew.
Yellowing leaves are a common symptom across several diseases that can affect hoyas.
The majority of hoya diseases are dealt with by removing affected leaves/roots and then treating the rest of the plant with a fungicide.
Here is a great resource if you want to dive further into all the different types of diseases and how they are controlled.
7. Not Enough Sunlight
Yep – just like watering you can get too much or too little sunlight on your hoya.
Sunlight is obviously important for plant growth, and without enough sunlight, photosynthesis is greatly reduced which can stunt growth and cause leaves to die, turning yellow in the process.
The best type of sunlight for most hoyas is bright and indirect.
You should aim for at least 8 hours per day of this type of sunlight.
8. Poor Soil
Soil can be poor quality for hoyas for two main reasons – a lack of nutrients or a lack of drainage.
Poor drainage leads to overwatered soil which leads to yellowing leaves. A lack of nutrients leads to reduced leaf growth and photosynthesis which also causes the leaves to turn yellow.
Using the wrong soil mix indirectly leads to other issues that cause yellowing leaves so it is crucial to get it right to set your hoya up for long-term success.
My preferred soil mix is this (get the full breakdown here):
- 3 part compost
- 1 part perlite or bark
- 1 part sphagnum moss
- Optional pH modifier
You obviously don’t have to follow my recipe but make sure your hoya has well-draining soil packed full of nutrients and you should have no issues.
9. Natural Causes
Every now and then some of the leaves on your hoya will naturally die.
This is part of the life cycle and not something that you need to worry about.
If you notice a pattern with the leaves yellowing and dying then it is likely one of the other issues, but if it only affects a leaf or two at a time then it’s probably nothing to worry about.
What Should Healthy Hoya Leaves Look Like?
Healthy hoya leaves should show no signs of regular yellowing or browning and should be quite firm to the touch.
It’s perfectly normal for a few leaves to slowly die and fall off, but this should only be a very small amount of the total leaves.
I hope this guide has covered everything there is to know about hoya leaves turning yellow.
Feel free to use this as a go-to guide any time your hoya leaves start to turn yellow to quickly get your plant back to health.