I have a 4 year old ficus triangularis. Recently, a lingering issue--which hasn't caused any issues in the past--has gotten worse. I have not moved it, and I maintain a very regular watering schedule, which I vary according to the season. Leaves are curling and turning yellow. There are brown spots on the backs of some leaves. I've tried cutting back on water, and also watering more frequently. I have a soil meter to measure moisture, and the soil is usually dry in the top 2 inches. I've also flushed the soil because I thought it might be too acidic. It's not adjacent to any plants, and it lives next to a permanently shut window. So I'm not sure how pests might access it (so I'm assuming that's not the issue--but I could be mistaken). I suspect something else is going on, but I have no idea how to troubleshoot this issue. Please advise.
I suspect your Ficus triangularis is not getting enough light, especially on the side away from the window. There may be other things going on that I can't tell - hopefully others will offer their opinions too. Since you have ruled out the likelihood of improper watering and disease/insect problems, I think your first course of action should be to either move it to a brighter spot or supply special grow lights to supplement the natural light. From: How to Grow a Ficus Triangularis Plant "Without bright light, it will lose its leaves. The ideal place in the home is one that is lightly curtained and faces south, east or west."
Thank you, Margot. You could be right--for this time of year. It's a south-facing window, and right now the light isn't as bright as the rest of the year. However, fall-winter-spring it's extremely bright and the tree grows super fast. Despite the high growth rate, I still experience leaf curling and those odd spots on some of the leaves (picture #3 above). Could it be mites, or some other invisible pest that somehow got in??
The yellow mottled appearance makes me wonder if it is a nutrient issue, but I don't know enough about Ficus to say what it needs or has too much of.
I wonder about nutrients too and think the problem with your plant is cultural. The website I recommended (How to Grow a Ficus Triangularis Plant) gives very detailed instructions on fertilizing. I have a feeling that if you repot the Dracaena, give it more light and some fertilizer you will begin to see an improvement in its appearance. By the way, although very small, spider mites are visible even with the naked eye so you might expect to see little red 'things' scurrying about but use a magnifying glass to be sure. There is often webbing too if spider mites are present.
