Garden lighting

I think wall lights would look nice. Maybe some solar lights ?

some 'up lighting' will look nice as the plants get bigger. Forget solar lights as I bought 2 'flood solar lights' with led bulbs, they only glow like sidewalk light, not really highlighting the wall. a kit needs the transformer, lights and wiring and a place outside to plug them in.

i would use floodlights pointing up through the base of the palms

You might find some ideas here: https://www.pinterest.com/explore/outdoor-garden-lighting/?lp=true

Solar lights would be easy to install and flood lights pointed up against the back wall will high light the new trees best.

I think you really need to evaluate the effect you want to impart. Hard wired lighting offers a lot more options than solar (which, even though we have some solar, in my humble opinion it is limited at best). If you want drama...go for up lighting. If you want subtle lighting sparkle...go for fence mounted down lighting that does not glare in your eye as you are walking past (search "dark sky" lighting). If you want ambiant lighting to enjoy the outdoor space at night for cooking or entertaining...go for fence mounted exposed light fixtures. OR..consider a mix of all of these with some solar add ins. Have a buddy join you at night in the dark and play with flash lights. Place it at the base of a plant, point it up and towards the plant to see the shadow it creates on the wall. Also, have them hold it over the top of the plant as though it were mounted to the fence and see how it highlights the plant. You will get a very real sense of what you can achieve through this process.

I’ve always been disappointed with solar lights. But they’re a temporary solution till you figure out what works best for you. I Have a very shady yard, which is problematic with solar, but even with full exposure their longevity is disappointing.

I really like the idea of "up" lighting. I've always thought that type of lighting gave the most beautiful look and highlighted the look of the trees/plants. Wishing you the best!