Good afternoon Pat,

You mention your 40 year old Ficus is dropping leaves. Can you tell me if the leaves are yellow or appear damaged ?

 When the Ficus was repotted 3 to 4 years ago , how large was the pot it was placed in?

What was the potting material used and did the roots appear in good health?

How frequently was the plant moved and is it in bright indirect light?

Would you be able to provide close up pictures. 

Stone or gravel placed at the bottom of pots will sometimes create a "false" horizon which will sometimes cause the planter to hold water rather than allowing it to drain, Ficus enjoy being moist but wet will cause root rot . 

40+ years may be the life expectancy of an indoor potted Ficus. On average 20 to 40 years is expected. 

If possible please get back with me on this, I will be doing more research on Ficus in the mean time 

The current pot opening measures 19w x 17h.  I don't know how many gal.  When I first repotted it I was unaware that indoor potting soil is not always screened for pests (fungus mites).  It was re-repotted - new/old soil removed and replaced with non-mite soil.  That problem was solved but what a nightmare. I really didn't examine the roots (or would know what to look for) during the initial repotting.  It's a lot of tree to move around.

The light is indirect - faces south.  I keep the east window blind closed.  It's previous location downstairs was probably  too close to the hvac register.  Ficus sits back further in it's current abode.

I've never really known how much to water and frequency. Maybe 1/1/2 to 2cups a week. The soil usually appears dry as far as I can reach my finger.

Thanks for your assistance!

Good Afternoon Pat,

Please allow me to begin by observations from your previous notes and the picture provided. Then we will go through Ficus by the numbers , or what the plant wants to be healthy. 

As I mentioned earlier stone placed in the bottom or layered into the soil medium can create a false horizon , or soil layer, which will sometimes hold water at lower levels causing the roots to remain wet , which can lead to root rot. It is better to use the potting material and leave out the stone or charcoal. The soil is blended to retain the needed moisture and allow excess to drain away . 

When repotting the size of the pot should only be slightly larger than the existing pot , maybe 2 inches across the diameter larger. New soil should then be added around the circumference and lightly pressed in to eliminate air pockets. If the roots are compressed around the circumference , lightly brush them with your fingers to help loosen them and aid in their moving into the new soil medium. Repotting should be done approximately every 2 to 3 years. 

I see in the picture the plant appears to be well placed from the window, allowing good indirect filtered light to the plant . Plants are best placed by East or West facing windows and when placed in South facing windows the light will need to be filtered. 

I also notice the heat register in the picture. Changes in temperature and drafty conditions can effect the plant and will also cause leaf drop. 

As I stated earlier , A Ficus of 40+ years is a well lived plant. So now lets take it by the numbers and see if we can get you another 40.

Light : Bright, indirect light is what we and our plant are looking for. However bright direct sunlight can cause the leaves to scorch. Ficus should be near east or west facing windows or a few feet away from a south facing window with filtered light . Rotate the plant every so often to help maintain a uniform shape. Low light conditions will result in leaf drop.

Water: Water thoroughly until water drains from the drain holes in the bottom of the container, discard any excess water. Allow the top inch or two to dry out between watering. Overwatering can result in root rot, water less in the winter as plant growth has slowed. and placing the pot on a tray filled with gravel and a little water will help add humidity for the plant

Soil: A good quality , rich, well draining potting mix. 

Temperature and Humidity: A consistent temp is best , between 60 and 85 degrees not allowing the temp to get below 60. Avoid drafts from heat and air conditioning vents and open windows, temperature swings will result in leaf drop. Consider a pebble tray or humidifier or lightly misting the plant . Air conditioning and forced air heat will dry out the plant and cause leaf drop. 

Fertilizing: Fertilize during active growing season using a balance liquid fertilizer at half strength monthly. Stop fertilizing for the winter or dormant periods.

Repotting: Repot every couple years or when roots become visible in the drainage holes. The pot should be only slightly larger than the root ball. Repotting is best done in the spring when the plant is beginning new growth spurt.

Pests and insects can be treated with insecticidal soaps or neem oil. As with any Individual pest management , read and follow all instructions provided and use the least amount necessary to treat you plants

Ficus will drop leaves when moved from one location to another until they adjust to having been moved, that is normal. I did not mention pruning as I feel it would be better to have someone , well versed in pruning ficus, walk you through the process and assist you to maintain shape or form. A good reputable nursery in your area can be helpful with that.