Like pictured, mine is old.... probably 1989ish... and covers a long fence. The roots are now quite large but aren't near anything on my side to raise-up; and the nieghbors haven't complained since their driveway is right on the other side of the fence. They don't seem to interfer with anything I want to plant directly in front of them. I don't have very good soil.... basically adobe, so I don't think they need really good soil. However, they do get what little fertilizer there is from other plantings. I don't know the need for a raised bed, but I guess you can build one for looks - IF you want that.

One note: the sheered, flat look with small leaves - like in your photo - is made by constant pruning back of the foliage. The foliage wants to be big fig leaves and grow all over. My gardeners take care of that. If I had to prune this constantly I'd rip it out. I have included a photo of mine... and it needs pruning in the photo. Also, one consideration will be that this plant has stolens - grab-ons - that hold it onto the wall. Maybe this doesn't matter, but I wanted you to be aware of it.

As you can see, it makes a good background for other plantings AND a creates a dense wall over the fence.

@CA Kate z9 I realize you do not want the work of pruning it, but I will say your wall would look very impressive after a crewcut.

So you are saying you have a hard clay loam soil and the fig manages to thrive even without much organic content and with minimal oxygen penetration into the soil?

I don't think plants use oxygen from the soil. They take in CO2 and release O into the air thru' their leaves. Adobe can make a hard coating in the hot summer to protect the soil underneathe; it becomes mush with water. I don't think it is bad soil; and imagine that there is some transfer of oxygen, etc.

As for planting in this soil - my gardeners dig a hole, stick in the plant and backfill. I just redid a whole bed outfront and planted roses, Agapanthus, and some airy plant. They just planted all as explained and everything is thriving. (Of course, summer isn't here yet.) You can always amend the soil along the whole of the wall before planting. There is a theory (?) that plants do better when you don't change a small part of the soil where they will be growing; it changes the flow of water between different soils and the new plant will suffer.

As for figs in CA: this area was once a huge fig orchard; they cut that down and put in a subdivision. Occasionally I have a fig come up out of nowhere and start growing. (See my other thread.) Don't underestimate the power of a fig!

@CA Kate z9 Believe it or not, plants also "breathe" oxygen and produce CO2 as the output. This is referred to as plant respiration. Respiration happens in the roots and does require oxygen saturation of the soil. This is one of the main reasons that some plants cannot survive in moisture-retentive soils that drain poorly Rhododendron will never do well in heavy clay soils, for example.

Plants do photosynthesis, converting water and CO2 into glucose (for energy) and oxygen. The amount of oxygen produced by photosynthesis greatly exceeds the CO2 produced by plant respiration. But both processes exist. And it follows from these facts that at night when there is no light, your plants are giving off CO2, not consuming it.

As you will.....