In Zone 0, only non-combustible materials can be used. So, this means you’ll need to choose inorganic mulches, such as rocks or pebbles for areas within 5 feet of your home.  In Zones 1 and 2, however, some organic mulches are okay. Composted wood chips are the best choice in these areas but use them strategically. You want to break up areas that have mulch; you don’t want a continuous row as this can continue the line of fire should it ignite.  For example, think about creating flower bed “islands” that are mulched but bordered by inorganic materials like rocks. If the mulch does ignite and start to spread, the rocks bordering the bed will stop the fire from spreading beyond that bed.