Question
I have a fiddle leaf fig (about 4 feet tall) that has developed large brown spots since I brought it home. I have repotted it into a larger (and better looking) container. I water it when the soil on top is dry, although it doesn't seem to dry out very much. I have noticed fungus gnats in the last week or so. I sprayed the soil with a neem oil based fungicide/insecticide. I don't know if that's appropriate. The fig is in a room that receives south light, but I have been keeping the blinds closed in the day because of the heat. I live in the upper midwest, and do not have AC. The apartment can have a wide temperature variation in the summer.  It ranges anywhere from 70 to 95, depending on external temps. It has not dropped any leaves, so that's good.

I had read another answer to a question about fiddle leaf figs with brown spots being from acclimation to lower light. I lost my receipt, and can't afford to splurge again for another large tree. What specific things can I try that may make a difference? When is it too far gone?

Answer
Hi L,

You have two serious problems: not enough light and too much moisture around the roots.

South light is wonderful, but of no value if the blinds are closed. If keeping the blinds open during the day due to heat is a problem, then its probably best that you not try to keep plants. No plant can survive without good light.

The fungus gnats are a result of the unnecessary repotting that you did. New plants should not be repotted and it is unlikely that yours needed a larger pot. (For a more attractive look, it is best to place the nursery pot inside a more attractive planter of your choice.) The soil that you added was contaminated with fungus gnat larvae. In addition, by adding soil, it now takes a lot longer for the soil to dry out. Although that may mean less watering for you, it also means the roots are staying wet for too long and are now rotting. The rotting roots provide the decaying organic matter that the gnat larvae feed on.

If you cannot provide uncovered window for your Ficus lyrata, then nothing else you do will matter. If you can provide better light, then you will have to undo the repotting that you did. Remove and discard all of the soil that you added. That will help remove many of the gnat larvae. Put your plant back into its original or same-sized pot. Allow the top inch of soil to dry out in between waterings. Do not fertilize it.

There is nothing that will make the brown spots go away, but providing proper light and allowing the soil to dry out regularly will lead to healthy new growth in the future.

I have written an article on repotting that I will email for free to you (or anyone else) who sends a request to me at [email protected].

Please let me know if any of this is unclear or if you have any additional questions.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

Visit my website at  www.HorticulturalHelp.com