There’s quite a lot of confusion about how often to water Hoya.
There are two camps: one that rarely water, and the other that waters frequently.
In my opinion, Hoya do best if they’re kept in very airy soil and water frequently BUT they do totally fine in denser soil if left to dry out completely.
How do you know when a Hoya needs water?
When I was doing research after I bought my first Hoya, it was recommended that you wait until the Hoya leaves are wrinkled before you water.
Personally, I think that you’re leaving it a bit long between waterings. It’s a bit like leaving plants to droop before watering them – it’s likely totally fine, but also…they would prefer it if you watered them before letting them get that dry.
I use a moisture metre to test when my Hoya need watering. I stick the probe in the soil and if it gives me a reading of 2 or below, I water.
In summer, I keep a few Hoya in my bright living room window, and they usually need watering every day. My Hoya bella, in a north-facing window, might only need watering every three weeks.
Many house plant people hate moisture meters (it’s very much a matter of personal preference, though if you use a moisture meter be aware that they can be inaccurate, so double check with your finger) and prefer to use the taco test.
What is the Taco Test?
Hoya have pretty succulent leaves that store water. As the moisture in the soil depletes, the plant pulls reserves from the leaves, so the leaves become more floppy. If you can fold the leaf like a taco, it needs watering.
EXCEPT
(Right, ok, the world’s foremost Hoya growers recommend the taco method, and just because I can’t do it doesn’t mean you shouldn’t try)
The Taco Test has its limits. For example, I tried it on this Hoya Pubicalyx:
It looks like a Taco! And yet it’s still wet!
I checked the soil – it’s definitely still wet.
The issue is that the taco test doesn’t work on new leaves, so bear that in mind.
Also, some Hoya, like Hoya Kerrii, are naturally very rigid, and they would have to be dry to the point of shrivelling up to taco (I have never used taco as a verb before, but here we are).
Can also confirm that Hoya bella is too delicate to taco properly, and now I have a snapped leaf.
There’s also the issue of Hoya Krinkle 8, which was born a taco:
That being said, it works fine on Hoya Krimson Princess, which I suppose is probably the most common out there.
Just be careful is all. Don’t forget to check the soil as well as the leaves.
What affects how often Hoya need watering?
There is not one plant in my house that has a consistent water schedule, because various factors affect their water intake.
(Apart from the orchid, that I soak weekly)
Hoya can go WEEKS without needing any water, but then in the middle of the growing season, can need watering twice a week, especially if they’re large and in bloom.
These are some of the things that can affect the frequency at which you water:
Temperature
When it’s hot, plants need more water.
Yeah, yeah, I know you already knew that.
The reasons are threefold:
- The water evaporates quickly
- The plant needs more water to maintain adequate hydration because it’s losing it faster
- The plant is growing quickly and therefore using even more water.
Humidity
HOWEVER
If your room is really hot but pretty humid, you may not need to water at all.
We don’t water our terrarium (although we do run a fogger to maintain humidity) and it gets pretty warm.
In general, the hotter it gets, the drier it gets, but not necessarily.
I suggest investing in a hygrometer (they’re like, a tenner) and keeping an eye on your humidity when it’s hot.
When it’s really hot and your humidity is low (40% or below) then check your plant’s more often to see if they’re thirsty.
For example, I usually check my plants on a Thursday, but in hot weather I do a check in on Monday too.
I also have certain plants that dry out quickly – my Hoya bella is about to pop with blooms and whilst she never needs more than weekly waterings, she might prefer them every 6 days rather than every 7.
I do NOT pay that much attention to my other plants – she gets special treatment because she’s pretty.
Light
In summer the light is brighter, hotter, and lasts longer so it makes sense that you need to water Hoya waaaay more often in summer.
I think I watered my Hoya like, twice last winter. It’s dark! And damp! She didn’t need it!
Soil
Hoya are epiphytes, so they *technically* don’t need substrate so much as they need a crevice in a tree.
They live perfectly happily in soil but the vast majority of Hoya come in soil that isn’t particularly suitable for them.
Now, Hoya are pretty chill plants, so being in an unsuitable soil mix won’t bother them too much so long as you water them properly.
However, when it’s time to repot (and it can be years before this is necessary – they have shallow roots) you may find that the soil closest to the roots is incredibly compacted – often it’s pure coir.
In my experience, they like a chunky mix of coir, orchid bark, and perlite, with a few worm castings and some charcoal for nutrition and to keep mould at bay.
Pot material
As I said, are slow growing and shallow-rooted, so it can be literally years before you ever have to repot them. My Hoya bella has never moved pots and she’s massive (easily quadrupled in size since I got her, but her roots haven’t really grown).
Currently, all of my Hoya are in plastic nursery pots, and they seem to really like them. I have kept them in terracotta before, but for me, they dry out too quickly.
If you’re an overwaterer, it might be perfect for you.
There are rumours that terracotta isn’t suitable for Hoya because the roots can attach to the pot and get ripped off when you move them BUT if you soak the pot the roots will come away easily.
What kind of water is best for Hoya?
A lot of Hoya keepers (that doesn’t seem like the correct term, but oh well) recommend only giving them filtered water but mine have never, ever had an issue with tap water.
Now, I do have good tap water, so you may want to try filtered water if you have mystery black marks on the leaves BUT Hoya are quite succulent, and succulent plants tend to be less fussy about water quality.
Do Hoya like their leaves wet?
They don’t really care.
HOWEVER Hoya like high humidity, and wet leaves (or misting) does not equal humidity.
If you do get a Hoya’s leaves wet, make sure they dry quite quickly, otherwise you risk introducing bacterial infections.
Final thoughts
Hoya like to thoroughly dry out before being thoroughly watered again. The key to keeping Hoya well is keeping the humidity up, because the rainforests they come from in the wild are really humid.
Hoya can take a decent amount of underwatering, but won’t tolerate overwatering for long.
Not only will they rot, but because Hoyas have such small root systems the whole rootball can rot away pretty quickly and you’ll have to chop and prop (and Hoya take their sweet time to root).
Hope this was helpful. If anyone has any tips or more info about the infamous Taco Test, please leave me a comment.
