Are there any private gardens that our open by app. also?

Between Tel Aviv and Jerusalem is a wonderful nature and education center on plants grown during biblical times. Neot Kidumim

In Aswan Egypt there's Kitchener Island in the middle of the Nile. All of this small island is a botanical garden that has been there since the late 1800s.

If you make it to Aswan it's a great lazy afternoon trip to hire a felucca to take you across to the botanical gardens where it's often just a little bit cooler than Aswan-proper, and you can wander the gardens, have a picnic, and escape from the sometimes frantic pace that is Egypt.

On the way back the felucca can circle Elephantine Island (which is larger) and from the boat you can view ancient hieroglyphs and a nilometer.

Check out the gardens at the Bahai Temple in Haifa. This Temple and the gardens are usually a major attraction for any tourist in Israel. There is a guided tour through the whole site.
Joe

There is another lovely Bahai garden in Acre. You need to check for opening times though
Jabo