- Lack of space for the roots : transplant in bigger pot with fresh soil
- 3 weeks in a tiny "pot" without external feeding : your soil must be running out of nutrients as the average period without feeding is around 3 weeks thanks to the soil nutrients but your "pots" are so tiny that thet must run out of nuts since a couple days even more. If you transplant in a bigger pot with fresh new soil you will be abble to wait for 3 more weeks but then start to feed with dry or liquid nutrients