Get a wide tray (the plastic kind with 1+" high sides used as drip trays under large pots). Fill it with stones and water, but make sure the water doesn't reach the top of the stones. Put your pot on there and the humidity will immediately improve - it's very important to a ficus. You can improve the lighting if you get a (relatively) inexpensive 1-2 bulb fluorescent fixture with full spectrum 40w bulbs. Leave it on 14-16 hrs a day hanging 6 inches (yes!) above the plant. Both of those things will make a big difference. Air conditioning is very bad for plants as well. Water only infrequently, and even less in winter (but don't let things dry right out of course.

At this time of year, Ficus b. most commonly defoliates as a photo-period response to decreasing light levels. You leave no clues (Did you recently bring it indoors? Has the light intensity changed in any other way, like a site change?) as to how that might have occurred, and where you live is always helpful in determining what advice to offer. It will also defoliate anytime in response to chill, particularly sudden chill, and as a drought response from either under or over-watering (Yes, over-watering causes a drought response as fine rootage is killed and the ability of the plant to move water to the canopy is compromised.)

Chill causes a surge in abscissic acid, which causes an abscission layer to form at the base of petioles (leaf stems) and leaves are subsequently shed to conserve moisture. Reduced light and drought response causes leaf abscission by diminishing the flow of the growth hormone auxin. A flow of auxin across the abscission zone is required to prevent the abscission layer from forming.

I cannot believe that humidity is to blame so early in the heating season, and humidity trays are more a nuisance than an aid. Ficus b. is rather well-adapted to dryish conditions, its leaves being rich in cuticular waxes, though admittedly it prefers humidity in the above 45% range & 60% is what I shoot for.

When using fluorescent fixtures, cool white at 3200 lumens are the best choice, The red end of the spectrum in the full spectrum bulbs is largely wasted on foliage-only plants and the o/a light output of the full-spectrum bulbs is substantially less. The cool whites are also about 1/4 the price.

Al

Humidity trays are good year-round (except possibly in mid summer if you live in a naturally very humid climate, and ficus love it them. I really disagree with you about the lighting - cool whites are not enough to do a good job, and I know many pro. growers who would agree.

Lucy - Here is what I base my humidity tray comment on: I checked the humity in a room with 2 digital hygrometers that measure in .1% increments. I then placed them in the foliage of plants that were set over large, gravel/water-filled trays (the bonsai trays you describe). Both hygrometers showed less than 4% increase in relative humidity, fairly insignificant and I suspect a good part of that increase was due to normal plant respiration rather than any added benefit from the tray. So, you can see I do my homework & I'm not just guessing when I post something unless I offer something like , "This is my best guess". ;o)

As for the light issue, perhaps you could invite one of your friends with the growing experience to support your conjecture? I don't mind if you disagree with me. Admittedly, I only touched on the science behind what this specific plant prefers in the way of fluorescent lighting, and this isn't to say that I cannot expand on it if need be, but even that modicum of science leaves you with the onus of supporting your refutation. In other words, show me/us the science instead of what you think someone else might think.

Al

I hadn't thought of chill. It got rather chilly for a few weeks before the thermostat was switched to heat.

And the photoperiod** has been decreasing rapidly since mid September.

I will ponder how to mitigate those two factors next year.

**One big east window in a tiny apartment in the high desert. Moving the plant, significant extra lighting etc. are problematic.

Albert, mine, many years old, is under a 4' bathroom skylight, I have a heat pump, and my ficus does the same as yours. It's only a couple of feet from a shower used at least twice daily, not to mention the standing 'bowl' of water quite close - I don't do anything else for humidity.

I think we've lost closer to 3 hours daylight here. I've just programmed myself to know I'll being doing daily leaf pick up for a few weeks, and the tree seems to recover nicely when the light lengthens again. Other than the person picking up leaves, I don't know that anyone else would realize it's more sparsely foliaged - and shop vac makes a little one gallon size that works great :)