Hi Rina,

Thanks for identifying the issue. From what I know oedema is not really a disease right? Improving air circulation help or maybe I should put some charcoal desiccant around the plants (not in the pot of course). Will that help? and will the leaves revert back to normal after adjusting the environment?

I've change my mix to a gritty mix after your advice in my other post. Now I'm using a pre-made mix includes pumice+akadama, some zeolite and the package contains small amount of carbonized rice husk and root rot preventative. I combine that mix with more perlite (adding roughly 30% perlite to the mix). I've some coco peat but don't think I will add it in since it is quite humid here. Still experimenting the proportion of the mix to suit my environment.

Have not water since I repot it which is around 2 weeks ago.

Thank you!

WJ

You are correct, it is not a disease. I do not think leaves will revert to 'perfect' state; there are usually little pimple-like bumps left on leaves. If the oedema blisters are large & they ruptured, they will scab over, so there will be a scabby brownish spot on the leaf.

Good ventilation helps, as would lower humidity - using small fan may help. After watering, pot should not sit in a saucer with water. I do not use peat/coco peat in gritty mix. I do not use any charcoal so not sure what it will do. The mix you describe sounds quite good to me.

I have semps overwintering outside, and they get covered by snow. So there is lots of moisture, but they are in very gritty mix. During summer, I do not water them, they get water when it rains. I don't remember having any oedema on semps, but I see some on few leaves of jades that were outside spring to fall. We have some humid days during summer, most likely not as high as in your location. We get reasonable rains, but it doesn't last for many days in a row.

Btw, do you know what is used as a root rot preventative in the mix?

Thank you so much for your advise Rina. I'll see what I can do to allow more air ventilation.

For the root rot preventative they did not have any description on the package which I get a little worry about that. Did a product search online for the mix that I bought, and I found this description for the preventative:

It looks like some sort of 'flakes'. Don't really understand what those chinese description mean though...Hope they will be alright

WJ

If you ever find out, pls. post. I do not have any idea what the green flakes may be.

If you put your semp outside, try to put it in area with filtered sunlight during hottest hours. I am only suggesting that since I believe that intensity of sun in your location is quite high. Because of that, you may be able to keep it indoors on the windowsill, without extra lights. JMO :)

Sure thing Rina. I will keep you update if I find out.

one more question...your idea of keeping the semp in shaded area outside seems nice. But what will happen to them if they have been living in warm environment in a long run? Since they like cooler surroundings.

Carbonized rice husk is essentially ash. That just clogs up all that nice akadama and the rest. Next time you use that mix, I suggest sifting it to remove the fine particulates. Humidity in Singapore is horrendous, this pot will be better off right in front of your AC with a light right on top of it.

Semps are Alpine plants. I've told my sister the only place she can grow this long term in the tropics is in her wine fridge with an LED grow light.

WJ

I am not saying it should be full shade, perhaps filtered sun - thru some trees, brushes or taller plants. Looks like your semp grew in lots of light (full sun outdoors, lights indoors), and has really dark color on leaves. But there is so many cv of semps, maybe it is dark one. They are alpines as Pagan said, and survive winters in z4, some even z3.

Pagan

What a novel idea, haha...controlled environment, for sure :)