Growing Ginkgo in Karachi, Pakistan

I am trying to find some information on growing and care of Ginkgo`s in places like Karachi,
we have 4 seasons, summers are from 32 to 42 C winters are from 15 to 22C sometimes lower at night to 10 C.
I have 3 ginkgo plants from South Africa , recieved 2 months back , have put them in a semi shaded , area under a tree, as the sun has been scorching hot around 40C in the past few weeks. All the three have retained 50% of their leaves one have 3 new leaves from a bud.
South Africa it was autumn when plants were shipped.
Please advice.
Question by /Ovais/ Secretary Pakistan Bonsai Society.