chong

I second that. The Pstem is retaining too much water. Further, I think that it could also be starving from light and ventilation. Put the plant in a brighter and warmer spot, and put a small fan nearby to circulate the air some. When watering, let the top 1/2" to 3/4" of the soil to dry out before watering the plant again. Make sure that your soil is well draining. I notice that your soil has some perlite in it already. However, if it's mixed with too much peat moss, it might be retaining water too long. If that's the case, you can add more perlite, or 1/4" grade pumice with your potting medium - 30% pumice to 70% medium ratio. The problem with perlite is they float to the top when you water with strong spray that disturbs the top of the soil. You will have to mix the top soil over each time in order to keep the soil loose. I use a soil-less potting medium made by Fison's Sunshine Mix and it's mostly peat moss. I got the tip to add graded pumice to it from the Horticultural instructor from the U of WA in a course that I audited back in the early 70s. The graded pumice that I used then was white pumice and they are much lighter than the red pumice that you get from landscaping or sand & gravel supply companies. The white pumice is especially helpful when you have to move pots in and out of the house for Winter storage and outside growing in the Spring. Though I still have and use the white version, since the late 90s, I've mostly used the red pumice now due to the very high cost of the white pumice. The last time I bought white pumice they cost 5 or 6 times the red version. Once you have the plants in the brighter light, you also need to develop a fertilization schedule in order to "fatten them up". Use half strength of the manufacturer's recommendation for the first 3 weeks, then go full strength after that. Follow the manufacturer's instruction on the frequency of applying fertilizer.

Best to you!

Chong