My ficus tree began to lose many leaves. That had happened in the past. Then we watered it too much and almost killed it by drowning.
But this time my wife said that she was sure she did not over-water it.
Well, the symptoms are the same; what to do? Ask a horary.
Is the Ficus too wet or too dry?

The ruler of creatures that grow in the ground or are rooted in the ground is the ruler of house 4 (in the garden or in a pot makes no difference), so Saturn here; clearly in my mind by its location on the ascendant.
Saturn is in Scorpio. Its dispositor is Mars, located in Leo showing a relatively severe fixed excess of heat and dryness (Fire).
Question answered. The wife is right, she did not over-water it. But probably went too far. The plant is dying from dryness this time.
What is the treatment for this condition?
Water the plant.
Outcome: in a few days the leaf dropping stopped and the ficus began to recover. Healing using the elements and horary diagnosis.
An important technical note:
One may be tempted to determine the ficus’ elemental imbalance by looking at the sign the planet is in only. Here Saturn is in a Water sign so one would mistakenly assume Saturn is too wet.
That is wrong, as this example clearly demonstrates. The correct astrological technique for horary diagnosis is to look at the elemental quality of planet’s dispositor’s sign. In this example it is Leo.
This is not my idea. It comes from Lilly. And thanks to John Frawley, who rescued it from an obscure corner of Christian Astrology, it has reached us.
If you disregard the dispositor you run the risk of harming whatever unlucky creature you do a horary for.
Here is an article illustrating how to harm with the elements >>