Ask Mr. Smarty Plants

Choosing a satisfactory native tree for you area can be tricky for Mr. Smarty Plants. Many communities in Southern California have blended the dry, hot, local climate with the green lawns and flower beds of other regions.  Finding suitable native trees for this mixed setting is not straightforward.  Many of the trees that your neighbors have are not natives.  Some characteristics of these are shown in the indicated website.  But there are native possibilities.  Oaks, for example.  I'm not clear what kind of oak failed to thrive in your setting, but I expect it was a species adapted to dry hillsides.  Perhaps Quercus engelmannii (Engelmann oak), which is an attractive tree in the right spot.  A related oak that is adapted to moist canyons is Quercus chrysolepis (Canyon live oak).  It might prosper in the clay soil of your garden, which I presume is irrigated.  Among other native tree species that you might consider are Lyonothamnus floribundus (Catalina ironwood), Arbutus menziesii (Pacific madrone), Chilopsis linearis (Desert willow), and Cupressus macrocarpa (Monterey cypress). Magnolia grandiflora (Southern magnolia), although not native to your area, does well in a moist environment if the soil is somewhat acidic.  Click on each species name to find its good and not so good attributes.

My long distance recommendations may not be entirely trustworthy for your particular microenvironment.  If any of these tree species seems desirable to you, you should contact local nurserymen for their thoughts or look around your community to see if the species is being used. Its absence would suggest that it may not be a good choice after all.