What is the life span of a ficus benjamina tree?

Answer 1

Considering the Ficus has an incredible diversity of growth types (from near herbs to clonal canopy trees) one number is most likely not going to be sufficient. Some say the oldest documented angiosperm on earth is a fig tree (the sri maha bodhi) but smaller house plant type figs may have lifespans starting at 20 years

Answer 2

I can confirm that I've had a ficus for 21 years. It is potted and has been both indoors and outdoors for extended periods of time. I have re-potted it twice into slightly larger pots.

I thought I lost it once during a surprise freeze when it was outside; all of the leaves fell off and the branches died. However, a few weeks later, new growth started from the root system (which had not frozen), so I trimmed the dead branches and it has exceeded its previous size.

So, 21 years of indoor and outdoor environments and one "half-death" and it's still going strong. I do stick a couple of small fertilizer sticks in the soil once every couple of years. I water it once to twice a week, depending how the leaves look:

Imagine holding out your arms to your sides; when you first start, you can easily hold them out and your posture appears firm and strong. When the leaves look like this (deep green, shiny, and prominent), it doesn't need water. If the leaves start to dull in color/texture, and/or they appear to droop a bit (as if your arms got tired and they are starting to fall a bit), then I give it water until the soil in the pot is saturated and runs out the bottom drain holes.

Mine is currently outside right next to the front door, so it's easy to gauge if it needs a drink because I see it every day.