All plants will burn. Some burn faster and hotter than others. Those that contain oil, sap, or resin ignite easily, burn intensely, and and make a fire worse. Those that contain water are fire-resistant, do not significantly contribute to the fuel, and can even slow advancing flames.
Our garden’s rosemary swaths and neighboring plants epitomize inherent fire performance. Rosemary was destroyed by the Thomas Fire, yet graptopetalum, aloes, echeveria, and dasyrilion just inches away had relatively little damage. Same flames, same location, totally different outcomes.
Species like rosemary or conifers are considered waterwise, but they are fire hazards. Succulents, on the other hand, are proven all stars both waterwise and firewise. Aloes, agaves, senecio, and portulacaria, to name our object lessons, contain water that enabled some to survive and reportedly helped save our home. Our experiences disprove 2 other fire performance misconceptions:
- Succulents don’t burn. Not true. No plants are fireproof. Depending on flame intensity and mulch type, many of our succulents fried to their core and died.
- Native plants are always fire-resistant. Not true. Chaparral or coastal sage ignite quickly as part of nature’s cycle. Baccharis pilularis, though, is slow to burn.
Why choose plants at the risky end of the spectrum when safer ones are available? Having seen first-hand its deleterious effect, rosemary tops my banned list. Future posts will detail plant attributes to avoid and other fire-safe landscaping tips such as placement, irrigation, and maintenance.