Weed worker's handbook

If you want to repopulate with native plants you have to remove the invasive exotics first. These exotics, the true "weeds" of California include things like scotch broom and many plants that we've come to associate with California such as fennel and mustard. These exotic weeds overrun our slow-growing natives and reduce the habitat that they provide to our dwindling native fauna. Sometimes it's hard to rationalize these plants as weeds because they seem so Californian, but that's only because we see native grasslands so rarely.

Caltrans has invested significant money exotic eradication, since they recognize the value of native plants for soil retention (for instance because of native grasses deep roots), lower fire hazard (because of less explosive spring growth and subseqeuent dieback), easy maintenance (once established without competing exotics of course), and low water requirements (again, once established). However, despite trying several methods of native plant cultivation, a joint UC Davis / Caltrans pilot effort along I-505 has utterly failed. People with an axe to grind, might believe that this failure suggests a cost of $8.8 million per acre to successfully restore a roadside to native plants.

Caltrans necessarily wants to focus on automated propogation of natives, so they aren't much into weeding. Fortunately, individuals who might want to make a difference on their own land or in smaller restoration efforts can put effort into weeding and there is an official publication to tell you how. The Weed Worker's Handbook is that handbook. It's targetted towards northern California exotic weeds, but there's plenty of good advice in there for us southern California dwellers.