Proper watering (it looks like a very good soil, so over-watering shouldn't be much of a concern), bright light (will tolerate full outdoor sun, but you might want to shade the pot) and regular fertilizing with an appropriate fertilizer. It's incumbent on you to ensure the plant is getting ALL the nutrients essential to normal growth. If any are missing or deficient, the plant will cannibalize itself, extracting mobile nutrients from existing organs to fuel new growth and subsequently shedding the usually older parts.

One leaf here & there isn't much cause for concern, especially if the plant is recently (re)potted, but a trend in that direction begs a closer look at what you're providing, culturally. That it's occurring in younger leaves might suggest a deficiency of one or more of the less mobile nutrients. If you share how you're supplementing nutrition, maybe something will make itself apparent .....

Al

>> One leaf here & there isn't much cause for concern, especially if the plant is recently (re)potted

Repotted a month ago, but the problem started relatively recently. One leaf (the youngest) fell off, and three more (next youngest) are also getting that same yellow blotchiness. You can kind of see this on the picture, I hope. This is 50% of the plant's leaves, which sounds major, although the plant is tiny, was free and there is no emotional attachment, just a rooting/growing experiment.

After repotting from perlite into gritty mix a month ago I've been watering every 2-3 days on average. You are right to say it's kind of hard to say when to water when one has little gritty mix experience - I definitely feel that. I've seen all the suggestions about feeling the wick and sticking a finger or a dowel in there, so it's just a matter of practice and observation for me at this time, I think.

I've been fertilizing with every watering, Foliage-Pro 9-3-6, 1/4th teaspoon per gallon. I've also been adding vinegar to all water as well, at 1 tbsp / gal.

Light has probably been insufficient. It's been on a window sill that never gets direct light, not even filtered. Just reflected light and shade. The windows have been open, so it's been getting a breeze. I've just now set it under a recently set up fluorescent light instead.

Any ideas what this yellowing could be? Thanks.

duplicate, sorry.

This post was edited by greentoe357 on Mon, Aug 26, 13 at 3:55

If it is the youngest leaves which are dying I think there is a problem. Old leaves are shed naturally but if the growing tip is in trouble there's something wrong. I think you are probably overwatering and overfeeding. And also I'm wondering what the vinegar is for?

Plus I'd check under the leaves for spidermites. They can cause mottling and yellowing. Ficus benjamina is also a favourite with scale insects so check along the veins under the leaves.

It's very doubtful you're over-watering, given the soil you're using, and you can easily double the amount of fertilizer you're using - 1/2 tsp/gallon at every watering through Sep, then cut back if you don't use supplemental lighting. I use 2 tsp/gallon on plants outdoors at temps between 60-85*, and withhold fertilizer for plants out of that range.That the FP fertilizer is acid-forming leads to the question, how did you determine that 1 tbsp vinegar/gallon of water is an appropriate?

DO check for mites - do you know how to do the white paper test?

If there has been a recent decrease in the light load the plant is receiving, the mottled foliage may be a result as the plant prepares to shed the foliage, but the plant's reaction to a decrease in light affects the older leaves first.

Al

omg there is indeed SOMEthing under the leaves - little off-white specs, kind of like little perlite particles. What a coincidence - just a few days ago I started taking notes on how to recognize different houseplant nasties and what to do about them, because I knew it'd happen sooner or later. Well, I guess sooner it is then!

These look like spider mites to me by the descriptions I've read. If so, should I spray soapy water all over the plant? What concentration? How often? How many times? Should I spray plain water after that to rinse the soap? How long should I let the soap sit on the leaves?

I do not think I can use the shower head to try to physically knock the mites off of the leaves because the ficus is so little. Would a sprayed mist of soapy water suffice?

Should I go directly to spraying neem oil or using pesticides? I am not opposed, although I hear neem oil is very stinky.

I took the plant off the light shelf, as it is very crowded there and I do not want to infect other plants. Will keep it in separate room - or is it enough to just place the plant so that the leaves simply do not touch other plants?

I started checking all my other plants. Nothing like this ficus pest anywhere else that I can see, BUT I found THIS on my amaryllis. Are these mealy bugs? I guess the universe REALLY wants me to use my pest notes extensively. Grrrr.

And another amaryllis pic.

To answer your other questions, which probably matter much less now, but still...

Flora, vinegar is to lower pH of my water. See this: http://forums2.gardenweb.com/forums/load/contain/msg0612005017703.html. My understanding is it cannot hurt and may help most house plants. I am willing to listen to whoever can tell me more than that.

My fertilizer dosage is in line with "maintenance" instructions on the bottle, as opposed to "production" dosage which is 4-8 times higher. Soil is indeed very well draining.

Al, my plants are all indoors, so I did not want to go with higher fertilizer concentrations. I can be convinced otherwise as always. Any reading you can point me to?

Never heard of the white paper test until now. Google returned some results, I'll read up on that.

At closer inspection, I found crawling spider mites(*) on Shefflera Elegantissima, Croton, Alocasia Poly, Maranta and Calathea. The Shefflera was most infested and I am not in love with it anyway, so it went directly into the trash. The others got a soapy water spray.

(*) at least I think these are spider mites. Very small but visible to the naked eye relatively easily, brownish spots, movement is also easily perceptible to the naked eye (20/20).

How far away should I keep all affected plants from others? As long as plants do not touch body parts? Another shelf? Another side of the room? Another room? The other side of town?

Any other advice or reading for me?

>> These look like spider mites to me by the descriptions I've read. If so, should I spray soapy water all over the plant?

Update for those who may be considering their spider mite options: spraying soapy water did nothing other than give me really sparkling clean spider mites. :-) Now they must be even more attractive to each other for their little dates and their nasty mating every three seconds.

So, then I sprayed the plants with the flexible shower hose, trying to hit the underside of each leaf individually (trying not to think about little nasties flying all over my bathroom), and when the leaves dried, I do not see a single mite on any of the plants affected! I am relieved somewhat - not considering burning down my apartment anymore. Debating putting those plants back under the grow light next to other plants - but then giving them regular prophylactic underleaf showers and watching them like a hawk.

Oh, and I used this excuse to throw away the croton. It was ugly-looking to begin with, and it's a mite magnet, so there it went. The roots were much more extensive and healthier in gritty mix than they were in peatier more water-retentive soil the last time I saw them (Al, thanks if you are still reading this).

The amaryllis got a forceful shower right in-between the leaves. Other than washed out 1/3rd of the medium and slightly disturbed cottony stuff, that did very little. So rubbing alcohol treatment was next - q-tip in between the leaves to mechanically clean up the white cottony stuff. Then I dropped a drop of alcohol in-between each leaf for good measure. That one is definitely staying separate from other plants because mealybugs are so much worse than spider mites, I understand.