Hello all, I have had houseplants for years now. Including this rubber plant. But I am in no way really educated on the subject. I somehow managed to keep them alive with little trouble. I moved to a new apartment about a year ago. My Rubber plant is about 3 + ft tall. A few months ago it started getting solid, dried, brown spots on some of its leaves. Mostly just with one spot on the leaves that have this. Others dropped off. I repotted it around 4 years ago. I believe that pot is 2-3 times the size of its origional black planter. When I bought this plant it was of a good size so it wasnt cheap. Have since grown attached to it and want to save it. What could be the problem with my plant? Is there a better way to tell if its caused from under/over watering than by the guessing game. I've read its hard to tell. It sits in a west window room. I dont water but every 1 1/2 wks and the soil never dries out. Is it supposed to at the top? Maybe I use too much when I water? Any advise would help greatly. Its a pretty shabby tree now. It does have new leaves at the top and a few through out but not much. I relocated it to the west window room a mth ago from a shadier east facing window thinking maybe it wants more light. Maybe it needs repotted too? How do I tell? Thanks in advance!
If you could post some pictures that would be really helpful--there are lots of things that could cause spots and without seeing the spots all anyone can do is guess. I'll speculate here on a couple of possibilities, but seeing a picture of the symptoms and the plant in its pot will really help.
It sounds very weird that you only water ever 1.5 wks but yet the soil never dries out even at the top--does the pot have drainage holes? If not that could be your problem right there but I'm surprised that it waited 4 yrs for symptoms to show up. Or do you have a saucer under it to catch water? If you do, you need to make sure to empty that shortly after you water so that the plant's not sitting around with wet feet. The way to check for watering is to stick your finger down a couple inches into the soil and see how wet it feels. If it's been a while since you watered and it's still really wet, then either you're watering too much or you've got really poor drainage. If it's bone dry a few inches down, then you're not watering enough.
Possibility #2 is salt buildup in the soil. Since you said it's been 4 yrs since you repotted, that's a lot of time for salts from fertilizers, hard water, etc to build up in the soil. If you water thoroughly when you do water (really letting a lot of water flush through the pot and out the drainage holes) that can help slow down salt buildup, but after 4 yrs it's probably time for some fresh potting mix.
Possibility #3 is that it's gotten really rootbound. 4 yrs is a fairly long time between repottings, so it's possible that the roots have almost completely filled up the pot it's in, and when that happens there's a ton of roots and not much soil so it becomes very difficult to get the plant the amount of water that it needs. To see if it's rootbound, gently tip over the pot and pop it out--if you see a bunch of roots circling around then it's time for a larger pot.
And lastly, it always could be insects or a fungal disease of some sort.