It is very invasive. It grows extremely quickly and roots wherever the vine touches the ground. It has a twining growth habit and will strangle other plants if not trimmed very frequently.

There is a native morning glory.

http://www.laspilitas.com/nature-of-california/plants/1141--calystegia-macrostegia

Or maybe you go for a variety of non native clematis?

Yes, I saw this one on the Las Pilitas website, doesn't say anything about how invasive it gets...also white flowers r not as "wow" as the other varieties.

Per the folks at the Theodore Payne Foundation, it's manageable. But if you want wow go for non-native Clematis.

Non-native morning glory is a heartache. We spent untold hours pulling it out of our back woods. And, yes, it does strangle trees. Not worth it.

Morning glory is also poisonous. There are a variety of vines that grow on south facing walls in Los Angeles. Look up red or purple trumpet vine. Most clematis go deciduous in the fall or can die back when hit with frost.. just fyi

If the wall faces SW then you should consider Bougainvillea. What is the wall made of?

Trumpet vine is manageable you just have to trim twice a year..and I work all over LA with over 100 projects a year and there is always that residence each year that put in clematis and because of that one night of frost in the entire year and it will take the clematis down to the roots and they ask me why it died..hmm. Often it resprouts but on a 65' wall...

Agree; 65' of Clematis in So Cal isn't easily achievable.

In my experience native plants can be more enthusiastic pests than non-natives. Cercis occidentalis was a plague here.

Grewia can be espaliered against a wall. It needs no care, but it might be too messy near a pool.

Someone needs to create a sterile morning glory. Four years later I'm still getting seeds sprouting from next door trellises.