|some of new leaves on my potted ficus fold/curl up. I don't see any bugs.|
I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
It could have been that there was a bug that is now gone. If you see webbing inside there may have been a spider or caterpillar involved. Otherwise it may be due to one of several factors including very light damage from a weed killer used on the lawn (if the plant is nearby volatile gasses can drift on a warm day and cause problems), or some type of environmental stress such as a change in temperature. I suspect it is nothing to worry about and that it will be fine.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!