Oh dear! I'm so sad! I'll try to find a place where it can get more light. Why can't I repot it now? Because it doesn't have enough energy to survive the shock? The soil should be dry down to two inches below the surface between waterings, so about once a week, right?

I have never paid much attention to a "proper" repotting time for for any containerized plants, indoor or out. If it needs it, it needs it.........and yours does!! I'd not wait until June but do it now. Without it, I seriously doubt your plant will still be alive in June.

The reason I wouldn't wait is that remaining in the same (too small) container for 20 years without attention has resulted in considerable root congestion and depletion of any potting soil. When you water, it is a good bet that the water just flushes through the container very quickly, without a chance for the roots to take it up adequately. Lack of water uptake, lack of adequate light and most likely, lack of any fertilization is what is ailing your plant. And you can fix all of those :-)

I've grown Ficus benjamina for more than 40 years and repot them when I think they need it - in midwinter as well as midsummer. All have responded very favorably - to the point where they usually grew so large I had to give them away and start over!!

btw, weeping figs are notorious for dropping leaves with any change in environment: moving from outdoors to in, moving from room to room, sudden changes in temps (drafts) and both over- and under-watering. Why figs drop leaves.

Well, it's had all of those. (Yes, both over AND under watering while I was trying to get my schedule and amounts right.)

So, what kind of pot should I look for? More importantly, what size? And what kind of soil and/or amendments should I include to give it its best chance?

First, you'd need to be up to the task of repotting.

Not to be confused with potting up (removing from pot and just placing in a slightly larger pot with new soil on the bottom and sides).

repotting:

means you remove the tree from the pot and remove ALL old soil around the roots. You'd need to untangle and prune any (im sure there are lots) of problematic roots. You need to keep the roots moist during the entire process.

Here you can learn about soils and how they work in containers.

http://forums2.gardenweb.com/discussions/2842847/container-soils-water-movement-and-retention-xxii

I know this is long, Heidi, but I've got personal experience with your situation. To be brief, I'm confident that this tree is not even close to death's door, and would be much better served by fixing the causes of its decline now so it can green up and be much healthier to deal with the stress of repotting next summer.

In particular, your ficus was thriving until three months ago, and we know that the decline was caused by low light and poor watering, which means that fixing the root congestion and soil aren't an emergency.

To be clear, gardengal is probably right that you could repot now without killing the tree, but because it would be easy to get it green again by correcting the biggest problems now, you would be best off waiting until summer to do major root work and put it in a great growing medium. Then you will be rewarded with a burst of new growth, and you'll soon be pinching growing tips and pruning to control its enthusiastic growth and tell it to fill in all those gaps left by dropped leaves.

My experience:

I have two smaller roughly five year old ficuses that were completely rootbound and were stuck in a dim corner. I often forgot about watering until leaves started yellowing and dropping, and the I'd fill their tall plastic 'saucers' and left the water there until they stopped soaking it up. In other words, I drowned the roots every time I watered, and maximized the amount of deadly mineral deposits in the soil. Aside from feeble attempts to maintain a few leaves, they had almost stopped growing entirely because their depleted energy reserves made them more vulnerable to attack and only allowed them to put our a few leaves at a time, and most of the buds and leaves that appeared were killed by spider mites.

But these are tough plants, so they clung to life for about three years before I finally cared enough to search for answers and found these forums. I immediately started treating the mite infestation, thoroughly flushed the pots (I swear I could hear them sigh with relief), fertilized with a weak solution of Foliage Pro, which has a great ratio of basic nutrients plus all the micronutrients plants need, moved it in front of my best window, which only provides mediocre light, and added bright white (not soft white) 5000k 100W led and cfl bulbs in clamp-on fixtures.

Two months later, each branch has about half a dozen new leaves, including some emerging near the stem (a sign that the tree is getting better). It's wonderful to see them getting so green, and I'm already reading up on how to prune them when they get growing again.

So Heidi, if I were in your place, I'd start by checking the leaves for spider mites with a bright light and a magnifying glass (they're tiny red dots on the leaves, and you may see little bits of webs on the leaves our branches). Ask about treatment if you find any. Then I'd flush the pot (details below), fertilize with a 3:1:2 ratio fertilizer (miracle gro general purpose granules are easy to find and the right ratio), move it to the best window I had, and put two 100 or brighter led or cfl bulbs in it for 12 hours a day, using a timer.

From then on, check soil moisture by pushing a sharpened 3/8" dowel all the way through to the bottom of the pot, and DO NOT WATER until the dowel comes out completely clean and dry (at that point there's still a lot of water inside the soil particles). When that happens, water until about 15% of the water exits the drain holes, let it drain, and then either tilt the pot at 45 degrees for 15-30 minutes after watering to remove excess water, or insert a wick into a drain hole and raise the pot up so the wick won't come in contact with the drained water.

You can wait until the surface of the soil is dry to start checking the soil moisture, but after that you should check daily until you have a feel for how long it takes for the poor to dry up.

About flushing: flush with lukewarm water, using about ten times the pot's capacity, then give it a weak solution of fertilizer. Use R/O (reverse osmosis) water if possible; water from supermarket water machines are usually $.39 per gallon, and that little pot will maybe need two or three gallons to do the job. My water is hard, so I used R/O water to flush, and because my tap water is hard I use water from my cheap faucet-mounted filter for regular watering.

And the reason midsummer is the best time to do something stressful is that 1) ample summer sunlight generates much more energy from the leaves than even a lot of winter sunlight can provide, and 2) the plant is programmed to put energy into new growth in summer, whereas in winter it wants to store it for use in the spring. From several people's experience, including Al (talks), who knows whereof he speaks, if you take two healthy plants and repot one now and one next June, the second will be in better shape next fall than the one you repotted a year earlier.

Sorry for my rambling post, and I hope it helps at least a little.

A minute after posting I remembered saving this excerpt from one of Al's posts. It's specifically about how to decide whether to repot a sick plant or wait until prime repotting season.

Sick and dying plants

"To determine the appropriate time to repot (from the plant's perspective), ask yourself whether or not the plant is likely to die before the ideal repotting time rolls around. If the answer is yes, an emergency repot might be in order ….. but whether it is or isn't depends on the reason for the decline.

If the plant is in decline because of a soil so poor you simply can't thanks rk with it and you're sure it will die before spring, do the repot or discard the plant when it dies. If the plant is in decline due to other factors, CHANGE the factors so the plant is NOT operating at the outer limits of what it's programmed to tolerate."

Thank you so much for all your comments and advice! I will start on all your suggestions to get this plant looking like the gorgeous photo above right away!

I do wish you thevery best and hope the tree comes around.

You really don't have much time though. If things aren't changed now, you'll lose the tree.

What are your options for more light? Watering needs to be kept on track too.

Ficus are really, really easy once you learn what they need.

They've gotten a bad name on the internet as a tough plant that easily drops its leaves.

Thats true if the tree comes from a greenhouse or higher light environment and then is placed in a dark corner of a room. High light for a plant and high light for a human are completely different. What we may see as high light may be low light for the plant.

Most also end up way over watering too.

A large bay window or supplemental lighting is needed.

Repotting this time of year really depends. As stated, if the tree can make it in its current pot and soil, wait. If it can't, an emergency repot would be needed. I have no way to know for sure since I can't check the tree personally. But I do know that it's not easy on it being in that pot that long.