The wall faces southeast. It gets a great deal of full sun. There is a small oak tree about 15-20 feet away.
Yes, I think I would get double knockouts. As I mentioned in another post, I'm really lacking blooms this time of year. The oleanders don't bloom until the summer heat really sets in. They are great but they grow so fast and I'm always paranoid about the toxic sap. I used to have some white ones behind the waterfall of my swimming pool but I replaced them with Mexican fan palms b/c I was paranoid about my then toddler son putting the leaves in his mouth. Now 6 years later, those stupid palms are so ridiculously tall that they are growing into my oak trees. I let my landscaper pick them out. Another reason I don't use him anymore...