Answer: There are several possibilities. The plants may simply be going through an adjustment period, especially if the growing conditions are far different than those they had been accustomed to. These plants are fairly resiliant however so I would look into some of the other possible causes. One would certainly be underwatering, and this can happen when plants are severely rootbound or when the water is allowd to run out between the side of the pot and the soil without soaking into the soil -- this often occurs if a plant has been allowed to dry out completely and then it is difficult to rewet the soil. On the other hand, overwatering can also cause leaves to yellow like that. This would be a stronger possibility if they have recently been repotted or if they are being drenched repeatedly or sitting in water-filled trays so that the soil is always soaking wet. Another possibility would be over fertilizing -- either fertilizing outside the label recommendations or occasionally a long term fertilizer will release in an unanticipated burst due to excess water or temperatures. Another possibility would be a buildup of salts, if you suspect that you could try leaching the soil. Yet another possibility would be too brightly lit a location, especially if they had been kept in a darker location previously. Check too for drafts, either hot or cold, and be sure that humidity levels are adequate. Next, you should examine them very carefully for any signs of insect activity. Finally, you might want to consult with your local County Extension (378-1327) and see if they can determine the cause or have any suggestions. I hope this helps you troubleshoot the problem.
Q&A Library Searching Tips