I have a few portulacaria afra plantings that I acquired last fall. They have recently begun dropping large numbers of leaves. A few of the leaves initially show some signs of damage, however others look to be OK. After dropping they turn translucent brown quite quickly. For watering, I wait until leaves start showing signs of needing water (limp/start to wrinkle), then provide a thorough watering. I have not changed the location of the plants in over 6 months. They are located in front of a large southward facing window and the nearest forced air vents have been sealed off. This condition is on most of my ports, and might coincided with a flush of new growth. I've sprayed with an anti-bacterial soap and water mix, which I have confirmed does not harm the plant (cured a previous bout of spider mites over the winter). Is this leaf dropping normal with a good flush of new growth, or do I need a better pesticide? Any insight would be appreciated. Thanks!

This is a bonsai forum, so your question is off topic, but I'll try and answer anyway:
The plant looks OK to me. The way you water it should be fine. Seems it are old leaves that are dropping, and the newer ones are fine?

The new growth is yet unaffected, I just wanted to reach out to see if anyone had experience with this before. Google et. al were not helpful in the answer. Thanks for the feedback.

FYI - My apologies. I was unaware that this was an inappropriate species for bonsai and that this was the wrong forum to request advice about potential pest/disease issues.

Xzavier wrote: The new growth is yet unaffected, I just wanted to reach out to see if anyone had experience with this before. Google et. al were not helpful in the answer. Thanks for the feedback.

I see there are some topics about portulacaria on this forum, you may find better answers there:
garden.org/forums/view/askatp/

P afra is not ldeal, but used, for bonsai.

They need heat and full sun. Havjng it indoors in an airconditions space is probably the problem.