Right now, the large leaves are the only source of food for the plant. Fertilizer isn't plant food. It only supplies the building blocks plants need to grow, keep their systems in order, and to make their own food during photosynthesis. You can see now why the large leaves should be left to feed the new growth until the new leaves are about 75% their mature size - that's when they stop being an energy sink and become net producers of energy. After that, or around Father's Day if the plant is doing well, you can cut the plant back to just above a vigorous new branch that will become the new leader. Al

I would like to add that 2 days prior to the leaves turning yellow, i sprayed them with neem oil solution mixed with water. I highly suspect that that was the root cause of this happening as it seems like only the area which was sprayed on are affected. ** Updated Edited**, the other Ficus that had been at my place for awhile was sprayed with Neem oil as well but those plants doesn't seem to be affected. I can safely assume that the Neem Oil wasn't the culprit? Just to add on some information that might be helpful: Tree was grown outdoor at the nursery and is about 9-10 feet tall, did a repotting, made sure all the old soil was replaced, no root pruning was done. I did however made a mistake of not fully rinsing the perlite thoroughly before using it. The weather here is very humid (example: a pair of soaking wet jeans would dry up in 2-3 hours of afternoon sun.) Can't seem to find any pest that could be responsible.

There are inherent limitations in a soil that takes 2 weeks to dry down to the point the grower feels it's safe to water again. We have to allow too, that since you haven't been monitoring moisture levels, the plant might be capable of going much longer between waterings, which would tend to increase the level of limitations associated with too much water in the soil. Given the size of the plant and the size of the container, the only way that can occur is by virtue of the fact the soil holds a lot of excess water. The soils I use require watering every 1-4 days, depending on the pot size and weather or indoor conditions. Keep in mind that most of my plantings are bonsai, so the ratio of plant mass to soil volume is very different than growing in a container as large as yours. I do have many dozens of plants growing on for bonsai in containers the size of the one you pictured and much larger, however. I think plantings that actually DO require watering every 2-3 days probably represent the best opportunity for plants to realize as much of their genetic potential as possible, but you'll need to decide weather or not you're willing to work toward getting to that point and subsequently making the effort it takes to water that frequently. Since we might never know what caused the leaf drop, it's probably best to confront the issue on several cultural fronts. My plan for the plant in the short term would be to take steps to significantly reduce the volume of excess water your planting can hold. That can be done in a variety/combination of ways. I'd see what I could do about getting it more light and maintaining a constant temp of about 70* or warmer. I'd flush the soil at regular intervals and fertilize regularly. Unless there are other potential limiting factors we don't know about, these suggestions should allow your plant to recover. Because the above doesn't go into a lot of detail doesn't mean I can't. If you're up for making the effort, you'll get all the help you need, a good part of it in the form of homework I'll link you to. After you read it, ask about anything it leaves you wondering about. Al

We didn't water the plant after we brought it over to our place because the previous owner advised us not to do it. Do you think we should water it? So the brown spots and the yellowing indicate a lack of sunlight, do you think? Regarding the soil: it is called Expanded clay aggregate ( https://en.wikipedia.org/wiki/Expanded_clay_aggregate ) From our understanding it is relatively unknown in the US. It is supposed to have certain advantages. According to the previous owner, the plant has always been planted within that kind of soil. Thank you so much for your help!