Fire Wise plant choices
9


9 Fire Wise plant choices

All plants – all organic matter – can burn, but the ease of ignition, rate of consumption, and generation of heat is vastly different between species of vegetation. Fuel is variable. 

Far more important than the actual species and its flammability is to be able to recognize and dispose of dead wood, which ignites and burns with much greater ease and intensity than living green vegetative material.

What follows is a list of plants used in landscaping around your home that are labeled either good or bad from the standpoint of fire (only). The lists are not all-inclusive, and many species – both bad and good choices – have been added to our landscapes from worldwide sources. Most of the common native plants are mentioned and more fully described.

Pyrophytic Species are “fire-loving” vegetation which is adapted to or which contributes to rapid burning, high heat output, and ember creation. 

Many brush species – such as broom, manzanita, coyote bush, and juniper – are highly flammable and burn with an oily heat. Anything that smells when crushed has oils which volatize and burn readily, including bay, fir and eucalyptus trees.

Chaparral species are those brush species which grow in dense, pure or mixed stands and which create impenetrable fields that burn with intense heat and are very difficult to suppress or control.

They include manzanita, coyote brush, buck brush, broom, chamise, mountain mahogany, as well as scrub oaks and other flammable species. Chaparral species are among the hardest to manage and to keep fire safe.

Nevertheless, these can be made fire safe with work. If near structures, all pyrophytic species should be removed, and all dead vegetation removed from the remaining species. What is left should be small trees, and healthy, well-separated selected plants which have had ground fuels removed. 

Resprouting may occur and need to be dealt with annually. Proper attention to timing of repeated removal of sprouts may encourage the roots to gradually lose vigor and die.

Conifers are evergreen trees that have needles for leaves, and most of these have resins and pitch in addition to a tendency toward twiggy growth. Coniferous species should be considered pyrophytic near homes. All can be made less flammable by pruning and removal of dead portions, but conifers tend to grow large and overtop other vegetation, making for potentially long flame lengths, if ignited.

At another extreme are the low conifers – juniper in particular – which contribute to rapid fire spread largely by becoming dense with un-maintained dead and dying vegetative materials that lie in wait for an ember to ignite. In addition to the listed and described species, obvious poor choices near homes include cypress, cedar, all pines and firs. 

The one native conifer exception is redwood, which tends to exist in more humid environments and does not have abundant pitch. Redwood can burn, however, as it can quickly accumulate large amounts of debris. Even with low flammability, maintenance and removal of dead vegetative material is key in all vegetation management to prevent wildfire.    

Hardwood trees, particularly deciduous species, are less flammable than conifers, with the notable exceptions of non-native eucalyptus, native bay laurel, and a few others. Most local oaks are low in flammability except for the live oaks (which appear evergreen). 

The live oaks should be kept in the landscape but pruned away from the ground, with dead material removed to avoid ladder fuels. If surrounding brush species are removed, the fire ladders are also removed and fire safety greatly improves.

This is generally the best course to take in the oak woodland portions of the Wildland Urban Interface (WUI). Excellent trees to have nearby that burn poorly (as long as you keep out the dead materials) are alder, ash, buckeye, cottonwood, maple, deciduous oaks, madrone, and willow. 

These should all be maintained free of dead materials and pruned high above the ground.

The following plants are further shown with pictures and descriptions due to their ubiquitous nature. For the most difficult plants, recommendations are made for effective removal techniques.

Napa Firewise

  To empower the citizens of Napa County with the information, knowledge, and support they need to survive a wildfire.