Hi Paula
I've just seen the previous replies to your question.
Of course there are exceptions to all rules and the Wisteria in Jesus, (which I have not seen) seems to be one. How many others are there? And it is probably drinking from a leak in the canal.
Against a botanist's advice I tried it, planted in the shade and watered. Waste of time and money.
If Simon is talking about L.Etrusca or L.implexa he is probably quite right but there should be no need to water except if they look unhappy in the middle of summer. No point in letting them die just for bucket of water.They are native to the Mediterranean and nobody waters them where they grow in the hills.
Bricon