I placed my ginger indoors beside a window, and they started growing. Some grew really fast, and some hardly at all. Why is this the case? Also, are their stems too weak/thin? I used a pair of wooden chopsticks to support one of the stems as I was afraid it would break. Do I need to add compost? I have been using potting soil all along (for the past two months).
Looks healthy to me! I don't think a support is necessary. If a cane grows too long for the pot, you can trim it (cut off the last 1/3 of that cane). Make sure they get as much light as possible, to avoid etiolation.
You don't need to add compost to a potted plant, but you can fertilize, if you can provide bright light as well. The reason some of them are bigger is that they came out of dormancy sooner. This is common in ginger, as well as other rhizomatus plantings (planted while dormant).
