Picture 2 & Piture 3:
Checked whether any root rot problem. May be caused by low intensity of light / incorrect soil composition. For temperature would not be the main problem as now is still in winter liked temp.
HK's winter is not really cold for Mexican Ping supposing that enough high intensity of light is provided, a little bit much water is required for the growth.
The growing method working for someone may not work for other person. Need try and error |