Sun-stressed hoyas are known for their unique aesthetic, but does the process of sun stress have any effects on the health of hoyas and is it something you should be doing?
Most hoyas can be sun-stressed but you need to be careful of overdoing it and scorching the leaves. Under controlled conditions, you can have a lot of success with sun-stressed hoyas.
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What Is Sun-Stressing?
Sun-stressing is a technique often confused with sun-scorching, however, the two are different things.
Sun scorching is what happens when a plant’s leaves become damaged by intense sunlight, whereas sun-stressing is a technique used by advanced houseplant owners to change the color of their plants’ leaves (usually succulents) using controlled levels of increased sunlight.
Sun-stressing causes plants to produce a pigment called anthocyanin which protects the leaves from UV. The result of this is a change to the color of the leaves, but how does this work for hoyas?
What Is A Sun-Stressed Hoya?
Most hoyas are quite well adapted to survive in bright sunlight and can produce anthocyanin when kept in such conditions.
Hoya sunrise is known for this, as the leaves turn from green to yellow and orange – colors of the sunrise, hence the name – when they are sun-stressed. Other hoyas that exhibit sun stress include skinneriana, deykwae and krohniana.
Can All Hoyas Be Sun-Stressed?
Most hoyas can be sun-stressed, but it is the colorful varieties that have better responses to sun stress than others.
A good rule of thumb is to look for hoyas with purple or red pigments on the leaves, as these are the most prominent colors for sun-stressed hoyas to adopt. You can try to sun stress most hoyas though, just keep in mind how much sunlight your specific variety actually needs before you start.
How to Sun-Stress A Hoya
The theory behind sun-stressing a hoya is to gradually increase the amount of sunlight that the plant receives.
To do this safely you need to avoid moving it to a place where the sunlight is too intense -it’s all about finding the right balance.
Here are a few steps you can follow to sun-stress your hoya as safely as possible:
- Step #1 – Move your hoya to a location with more sunlight. The ideal place should have plenty of bright, indirect sunlight. Keep your hoya in its new location for a week and then move on to step 2.
- Step #2 – After a week has passed, introduce some direct sunlight for a few hours each morning. Keep this up for a week and monitor the leaves closely.
- Step #3 – Monitor results. If you notice the leaves start to become sun-stressed when introduced to a few hours of direct sunlight each day then you can either continue or move your hoya back to a more shaded position.
When following the steps above make sure you keep an eye on your plant every day to check for signs of sunburn or scorch. Sun scorch creates patchy marks on the leaves that are brown in the center and yellow around the edges, and it can also cause the leaves to lose pigment.
Problems Sun-Stressing Can Cause
If you decide to sun-stress your hoya you need to be aware of the potential issues it can lead to.
Sun Scorch
The most common issue relating to sun-stressing is going too far and actually scorching the leaves rather than just stressing them.
Sun scorch causes blotchy patches or holes on the leaves that usually have a brown or black center with a yellow outline.
Underwatering
Giving your hoya more sunlight increases the rate of transpiration significantly, and can also cause moisture to evaporate more readily from the soil due to the increased temperature.
This means underwatering becomes much more likely. If you decide to experiment with sun stress I highly recommend checking the soil every few days and watering when the top two inches are dry – it will surprise you how quickly it will dry out in the new sunnier location.
Crispy Leaves
Another symptom of too much sunlight on hoya leaves is that they can dry out quickly and become crispy and brown around the edges.
This happens when transpiration increases drastically, causing the moisture loss from the leaves to become greater than that transported to the leaves from the roots. It happens more readily when the humidity is lower as well.
Would I Recommend Sun-Stressing A Hoya?
If you only have one hoya plant, I personally would avoid trying to sun-stress it. There is a good chance that you will just scorch the leaves and cause several of them to die, especially if it is your first time trying it out.
A good alternative would be to propagate a few cuttings of your main plant and then experiment with sun-stressing those plants first. That way you can get an idea of whether it will work or not without risking your main plant.
If you have several hoya plants then I would definitely try sun-stressing one of them to start off with, taking it very cautiously to minimise the risk of sun scorch.
