I believe this is a question that many hoya newbies have a problem with, and I can totally understand why. You can find so much opposing information about this on the web, that it is really hard to figure out what to do.
Many people say hoyas are like succulents, but I couldn’t disagree more. They are nothing like succulents. Hoyas absolutely love frequent and thorough watering! They just need to dry out between waterings. And this has everything to do with your potting mix and the size of the pot.
What I learned from hoyas is that they hate both extremes staying wet for too long and staying dry for too long. Both options will hurt the roots in the way that they will not be able to provide the plant with water and nutrients any longer. So before we go to watering, let’s go through two steps that will help immensely with avoiding the root rot and overwatering.
#1 The potting mix needs to be chunky, airy, and shouldn’t retain too much water. How will you know this is true? This basically means that when you water the plant, the water will almost instantly run through the bottom holes of your pot. You don’t need to wait a few seconds for the water to reach the bottom with the correct potting mix.
This is my potting mix:
#2 The size of your pot needs to be as small as possible. This doesn’t always mean the smallest you currently have at hand! 🙂 Until I got into hoyas, the smallest pot I had at home was probably 10 cm. This is way too big for small hoya cuttings! You need 5,5 or 6 cm. Like this:
If you can get clear pots, this is great, because this way you can check on the roots without disturbing the plant. When you notice any root rot, act quickly >>>
I get my pots from Ecuagenera Europe: https://www.ecuagenera-europe.com/zubehoer/pflanzgefaesse/klarsichttoepfe/
I can’t stress enough how important it is not to place hoyas in pots that are too big for them. If the pot is too big, there will be too much substrate and it will stay wet too long after watering. And this means root rot! If by some luck you can avoid the root rot, the hoya will grow very slowly or not at all. With a pot too big, the plant will work on building a root system for a looooong time before it starts working on leaves and flowers!
Here’s my hoya elliptica which stayed in the same 6 cm pot until it flowered for the first time:
I repot my hoyas in one-size (!) bigger pots when they dry out in less than 3 days after watering.
With a correct-sized pot, your hoya will never stay wet for more than a week, certainly not for a month.
When to water hoyas?
When I notice that my hoyas dried out, I water them immediately. I don’t let them go dry for days or weeks as I would do with succulents. If hoyas stay dry for too long, they will abort all new growth. If they stay dry for really really long, their roots will die off. In this case, they will not be able to uptake any water when you do water them eventually. The result is basically the same as if the roots would rot away.
Please never follow the common advice to wait for the leaves to get soft and wrinkled before watering! The plant is quite distressed already when you let her get to that stage. Think about how you feel when you forget to drink enough water during the day, and your brain membranes get soft and wrinkled. 🙂 Don’t give your hoyas a headache!
On the other hand, when in doubt, always wait. With hoyas, it is safer to be on the dry side, if you are not sure. Better to wait 2 more days and check again than to water while still wet. Hoyas rot really quickly and some of them don’t allow many mistakes with overwatering.
How to tell if the plant is dry?
In time, when you gain some experience with each unique plant, you will be able to tell this solely by the weight of the pot. When the substrate is dry, it is noticeably lighter. Pay some attention to this when you water the plants and eventually, you will end up with a reliable feeling. I always take the plant out of the decorative pot before watering, so it never sits in the water.
Until you get the reliable feeling, clear pots will be a great help with telling whether a hoya is dry or not! You can actually see the drops of water through the pot.
The good old ‘sticking the finger in the substrate’ also works! Just be really gentle and careful not to damage the tiny roots.
With hoyas, it is very important that the entire pot is dry, not just the top inch of the substrate. If I am not sure whether the substrate is dry all the way to the bottom, I peek through the bottom holes of the pot to see whether the substrate looks wet at the bottom or not.
How to water hoyas?
I always water hoyas from the top, never from the bottom. When you water from the bottom, the substrate will take too much water in and stay moist longer. This again means more chance for root rot.
Never water sparingly with only a few drops of water, this is no good. When the substrate is dry, you want to water all of it, not just the top. You need to get the water to all the roots, also the ones at the very bottom of the pot.
The only way to achieve this is to give the plant so much water, that you can see it running through the potholes at the bottom. This is why I always take the hoyas out of the decorative pots, hold them above a bowl (to catch the extra water), and water thoroughly. Then simply wait a bit till all the extra water drains (tilt the pot one way and then the other and gently shake) and place it back.
I have this same routine with all my plants, not just the hoyas. All of them appreciate it. It is a bit more work to lift and move every plant when watering it, but it is totally worth the effort. It also gives you a chance to check the plant frequently for any signs of pests or other damage.