Firescaping

Firescaping and Zone Zero

Firescaping involves selecting and placing plants and landscape accents to both protect and beautify the property. While there are no fireproof plants, some are slower to ignite and produce shorter flames and less heat if ignited. These have high moisture content, are low-growing, and lack flammable compounds. High moisture content plants are herbaceous, succulent, and green. They are non-woody and include grasses, flowers, bulbs, and some ground covers. These plants burn only after being exposed to sufficient heat, allowing the tissue to dry out, and they burn more slowly and less intensely than plants with a low moisture content.

The Zone Theory imagines your home as the bullseye of a giant target, with each of three zones spreading out in concentric rings. The first zone, Zone Zero (0), extends 5 feet from your home and is designed to withstand an onslaught of embers. The second zone, Zone 1, extends 30 feet and aims to stop a ground fire. The third zone, Zone 2, 30-100 feet, reduces the fire's severity. A Working Group of the State of CA is currently developing the specifics of the Zone Zero requirements, to be completed by the end of 2025.

Zone Zero

According to the initial comments from the Zone Zero State of CA Working Group, Zone Zero should only be planted with fire-retardant plants that mitigate the spread of fire. Zone Zero reduces the likelihood of structure ignition by reducing the potential for direct ignition of the structure from flame contact, by embers that accumulate at the base of a wall, and/or indirect ignitions when embers ignite vegetation, vegetative debris or other combustible materials located close to the structure that result in either a radiant heat and/or a direct flame contact exposure to the structure. Zone Zero is the horizontal area within the first five feet around the structure and any outbuildings, attached decks, and stairs. The zone also includes the area under attached decks and stair landings. To be most effective, the zone should incorporate a 6-inch vertical area between the ground and the start of the building’s exterior siding. Zone Zero is a critical component of structure defense and when coupled with Zones 1 and Zone 2, is essential to defensible space.

Allowable purposes for Zone Z include rock, pavers, statuary, fountains, cement, mature trees, parallel fences, irrigated and mowed lawns, potted plants in noncombustible pots, and irrigated, non-woody plants. An irrigated lawn with a maximum 2-3” height is permissible. Grass is a one-hour fuel. Thatch can burn under certain circumstances. Irrigated non-herbaceous separated plants are ok if: All ground cover (< 3” in height) and plants (< 16“ in height) should be minimally set back from structures, decks, and other plants 1.5 times the height of the plant or 12-inches, whichever is greater. Ground covers and plants shall have high water content.

What is NOT recommended in Zone 0 includes covered storage facilities, potted plants in combustible pots, wooden or plastic gates or fences attached to the building, landscape materials such as wood mulch chips, synthetic lawn, and decorative structures. Combustible decorative structures include pergolas, trellises, shade covering, planters, attached fences or gates, and privacy walls.

Drought Tolerant Plants

Plants that work well in a Firescape for Zone Zero include:

Aeonium, Agave, Aloe, Coral Bells, Penstemon, Sedum.

Plants that are fire-resistant and can be planted in Zones 1 & 2 (not Zone Zero) include:

Flowers: Achillea species (Yarrow), Coreopsis species (Coreopsis), Echinacea purpurea (Echinacea-Coneflower), Hemerocallis species (Daylily), Iberis sempervirens (Candytuft), Oenothera species (Evening primrose).
Groundcovers and Conservation Grasses: Agropyron cristatum (Crested wheatgrass), Ajuga, Cerastium tomentosum (Snow-in-summer), Creeping phlox, Helianthemum nummularium (Rockrose), Thymus species (Thyme), Vinca minor (Dwarf periwinkle).
Shrubs: Berberis species (Barberry), California Buckwheat, Euonymus species (Euonymus), Forsythia species (Forsythia), Hibiscus syriacus (Rose-of-Sharon), Island Mallow, Mahonia aquifolium ‘Compacta’ (Dwarf Oregon grape), Mexican Sage, Prunus species (Bush cherry), Rosa species (Rose), Russian Sage, Spiraea species (Spiraea).
Trees: Acer ginnala (Amur maple), Malus species (Apples and crabapples), Prunus species (Plum or cherry), Quercus species (Oak).

For a more detailed list, check out https://firesafemarin.org/create-a-fire-smart-yard/plants/fire-smart-plants/

(Marin is in Sunset Zones 15, 16 and 17, whereas we are primarily in Sunset Zone 15.)

Highly Flammable Plants

Commonly used drought-resistant (and deer-resistant) plants are often more flammable than most native plants. The dense growth, accumulation of dead dry leaves and stems, and the oils and resins contained in the plants render them highly flammable. Examples of highly flammable plants include Acacia, Bamboo, California Bay, Chamise, Coastal Sagebrush, Cypress, Douglas Fir, Eucalyptus, Lavender, Manzanita, Oleander, Ornamental Juniper, Rockrose, Rosemary, Scotch broom, Tan Oak, and some Ornamental Grasses. Care should be taken to not place fire-prone plants adjacent to any structures and preferably not within 30 feet of the house.