Hoya temperature tolerance is oftentimes a confusing subject, but it doesn’t have to be. The key to keeping your hoya happy is to know what temperatures it can tolerate, but what does this look like for hoyas specifically?
Different varieties of hoya can tolerate different temperature ranges, but most hoyas will do well in temperatures between 70°F and 80°F, with lowest temperatures of 60°F and highest of around 95°F.
After owning hoya for several years I’ve learnt a lot about how different types react to temperature and how important it really is.
In this guide, I’ll briefly explain the science behind temperature for plant growth and the signs you need to look out for to tell if your hoya is struggling.
- Why Does Temperature Even Matter?
- Hoya Temperature Tolerance For Different Varieties
- 7 Signs Your Hoya Is Struggling With Temperature (Too Hot Or Cold)
- How To Care For A Hoya In Hot/Cold Temperatures
- How Cold Is Too Cold For Hoyas?
- Can You Keep A Hoya Outside?
Why Does Temperature Even Matter?
An increase in temperature causes both photosynthesis and respiration to increase.
As the temperature becomes too high for a specific plant – in this case the hoya – these two processes become unbalanced.
This is why every plant has an ideal temperature range (as well as minimum and maximum values), and also why different varieties of plants can differ in temperature tolerance.
Hoya Temperature Tolerance For Different Varieties
Different varieties of hoya are adapted for different temperature ranges.
Take my hoya bella for example, pictured below. Hoya bellas are known for thriving in cooler environments with temperatures between 50 and 75°F, which is one of the reasons I decided to get one as my apartment tends to be on the cooler side.
Other hoyas, like patella and subcalva do better in warm environments with temperatures between 70°F and 95°F and can actually survive over this temperature range for extended periods of time.
The best piece of advice I can give here is to always check the type of hoya that you are buying and ask for care instructions.
Most places will recommend generic temperature ranges that suit most hoyas fine but always double-check online for ideal temperature ranges as well to be on the safe side.
7 Signs Your Hoya Is Struggling With Temperature (Too Hot Or Cold)
There are a lot of signs that your hoya is struggling with temperature, so I’ve decided to split them into signs that it’s too hot or too cold for simplicity.
Hot Temperature Symptoms
Let’s start with the key symptoms of it being too hot for your hoya.
1. Sun-Scorched Leafs
Warmer weather puts your hoya at risk of sun-scorch, which can cause uneven blotches on the leaves that will eventually turn brown and die.
There are certain types of hoya that can adapt to intense sunlight in a process known as sun-stressing, but it can be tricky to do it correctly.
2. Browning Leaf Edges
Browning leaf edges are very common on hoyas during hot temperatures for two reasons:
- Increased Transpiration – Moisture loss through the leaves increases drastically when the temperature increases. This moisture is usually lost first at the edges of the leaves and causes them to turn brown.
- Underwatering – Due to increased transpiration, and also evaporation of water in the soil, hoyas need to be watered more when the temperature increases. If you don’t water enough the leaves will turn brown at the edges and turn crispy and eventually die and fall off.
3. Yellowing Leaves
Yellowing leaves are another sign of hot temperatures, particularly due to lack of moisture and nutrients getting to the leaves if you don’t keep up with watering frequently.
They may also just turn yellow due to heat stress, and if the leaves are going crispy as well then it is likely a combination of this and underwatering.
4. Leaf Drop
When temperature increase hoyas lose more moisture due to transpiration.
A coping mechanism to reduce moisture loss is to drop leaves, which reduces the total surface area for transpiration.
If your hoya is dropping more leaves than normal then this is a key indicator that the temperature is too high.
Cold Temperature Symptoms
Here are the characteristic signs of how cold temperatures can affect hoyas.
5. Wilting Leaves
The first symptom of cold shock on hoyas, and most other plants, is the leaves starting to wilt.
This happens due to cell damage, but can often be confused for overwatering symptoms.
At this point, I would check the soil first to see if it is overwatered, and then you can figure out whether this is the real problem or if it is the temperature instead.
6. Discolored Leaves
The leaves may also start to turn yellow and brown as they die due to cold temperatures.
This can again be confused with overwatering so make sure you give the soil a good check before you self-diagnose the issue.
7. Stunted Growth
Overall growth slows down dramatically in colder temperatures.
There is a reason why you don’t need to water or fertilize a hoya as often during the winter months. Colder temperature means less photosynthesis and respiration, which means less growth.
How To Care For A Hoya In Hot/Cold Temperatures
Taking care of hoyas doesn’t have to be rocket science, so here are my tips for keeping your hoya happy during either hot or cold temperatures.
Hoyas become more work during hot temperatures, but the benefit here is that your hoya should grow significantly during this time as long as you can keep it happy.
- Water more often – Watering once or twice per week is my sweet spot during the summer, but you may need to water your hoya even more than this when the temperatures get high. Remember, higher temperature = more transpiration.
- Be wary of direct sunlight – Sunlight usually increases with the temperature, so be careful of direct sunlight during this time as it can quickly scorch the leaves, especially if your hoya isn’t used to it.
But what about when it gets cold?
Luckily when it’s cold (assuming it isn’t too cold) your hoya will become much easier to take care of.
- Water less often – I water my hoya probably once per month during the wintertime because it grows much slower during this time and therefore needs a lot less water.
- Keep away from drafts or windows – Don’t place your hoya too close to windows or in areas with strong drafts when it gets cold.
- Don’t fertilize – Fertilizing is not essential during cold temperatures for pretty much the same reasons why watering is not needed as much.
It really comes down to finding the right location to avoid drafts or extreme cold, and then watering around once per month and that’s about it.
How Cold Is Too Cold For Hoyas?
A continuous low temperature of 50°F is too low for most hoyas, and anything below this can become too cold even for the varieties that prefer lower temperatures.
Warm-loving hoyas need the temperature to be no lower than around 70°F, so again it depends on the variety that you have.
Can You Keep A Hoya Outside?
Hoyas can be kept outside as long as the conditions allow for it. In terms of USDA growing zones, you’re looking at 8-11 for the most optimal conditions for hoya growth, outside of this you can use a greenhouse.
The key to growing hoyas outside is placing them in the right location. Too much sun and you’ll burn the leaves, but too little and growth will be stunted and your hoya may eventually die.
I would recommend starting with bright, indirect sunlight and introducing a few hours or direct sunlight each day if you want.