Privacy and Screening Plants
Screening is a height and density question before it is a plant question. The entries here are tall enough and full enough to block a sight line: palms and larger yuccas, evergreen shrubs such as camellia, ceanothus and manzanita, trees like strawberry tree and incense cedar, and vines like bougainvillea that will cover a fence once they have something to climb. Most are evergreen, which matters, because a deciduous screen stops working in the months you are most likely to be looking at a bare fence.
Read mature height and mature width together. A plant that reaches fifteen feet tall and four feet wide screens a narrow gap, not a run of fence, so a real screen usually means several plants set at roughly their finished width apart. That looks thin at planting and is still the right call. Growth rate varies widely across this group: a vine or a ceanothus fills in within a few seasons, while palms and camellias are slow, and the slower growers are worth buying in the largest size you can move.