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Fire Wise Vegetation

Not to be repetitive, our area is currently facing moderate drought conditions which will become more severe as summer approaches.  The time to prepare for the fire season is now a year-around reality in our area and we should all be on heightened alert for the threat of wildfire throughout the year.

Based on tax values and census for our designated Wildland Urban Interface area, if a wild fire were to strike, more than 18,000 structures a combination of commercial, residential and accessory buildings valued at over 3 billion dollars would be lost and over 25,000 personal lives would be in jeopardy.

Last week our column addressed defensible space, what this means and how a homeowner can achieve defensible space.  Today we are going to talk about fire wise plant materials for our elevation.  It is important to safeguard your home and property and the time to start is now.

As we stated last week, all vegetation, naturally occurring and otherwise, is potential fuel for fire.  There are no “fireproof” plant species and plant choice, spacing and maintenance are critical; where and how you plant can be more important than what species you use.  However, given options, choose plant species for your landscape that are more fire resistant.

Keep in mind these general concepts when choosing fire wise plant species for your home landscape plan:

A plant’s moisture content is the most important factor governing its volatility.  However, resin content and other factors in some species keep them flammable even when the plant is well watered.  Conifers (a large group of resinous, cone-bearing trees and shrubs) such as pines, firs, spruces, junipers and Arizona cypress tend to be flammable due to their oil and pitch content, regardless of moisture status or content.  Many invasive weeds can also carry fire.  Two of the main culprits in our area are cheatgrass and red brome.  These species dry out just as wildfire season approaches so it’s a good idea to cut them down and remove before they set seed especially, on larger properties.

Deciduous (a term used to describe trees or shrubs that drop all their leaves to survive a cold or dry season – not evergreen) plants tend to be more fire resistant because their leaves have higher moisture content.  Also when trees drop their leaves in the winter, there is less fuel to carry fire through their canopies.

In some cases, drought tolerance and fire resistance are related.  Drought-adapted plants that have smaller leaves or very succulent leaves that store water can provide drought tolerance and increase fire resistance in your landscape.

Plants that are more resistance to wildfire have one or more of the following characteristics:

They grow without accumulating large amounts of combustible dead branches, needles or leaves.  They have open, loose branches with a low volume of total vegetation.  They have low resin content.  They grow slowly and do not need pruning.  They are short and grow close to the ground, such as small wildflowers and non-coniferous groundcovers.  They can re-establish following a fire, reducing the costs of planting new trees.  Most annual, biennial and perennial flowers have fire resistant characteristics.  It is important and homeowners are encouraged to work closely with local landscapers when selecting plants for use in their home landscape.  

The plants nearest your home should be more widely spaced and smaller than those farther away.  Plant in small, irregular clusters and islands, not in large masses.  Breaking up the continuity of vegetation with decorative rock, gravel, and stepping stone pathways creates a horizontal fuel break.  This will slow the spread of fire across your property.  Use a variety of plant species to support a mixed and healthy landscape.  Diversity of plants in the landscape will result in fewer insects and diseases and will better resist catastrophic fires.

Fire wise landscaping and functional well-conceived outdoor spaces are almost always complementary.  Plant choice, spacing and maintenance are critical.  Many native and local species are appropriate for fire wise plant materials.  

A landscape is a dynamic, constantly changing system.  Your landscape and the plants in it must be maintained to retain their fire wise properties.  Rake up and dispose of excess litter as it builds up over the season.  Remove annual plants after they have gone to seed or when the stems dry out.  Mow or trim grasses to a low height within your defensible space.  Use rock mulch to conserve moisture and reduce weed growth.  Avoid pine bark, thick layers of pine needles or other materials that can easily catch fire.  Remove all needles from roof surfaces, gutters, and within 10’ of structures.  From 10’ out, a 1’later of needles should be left on the ground to help reduce erosion, cool plant roots and add nutrients to soil.  Prudent irrigation of plants located close to structures is also recommended during fire season if you notice them drying out.

Next week our column will talk about a fire wise home.  

Our Prescott Fire Department and the Wild land Urban Interface Team along with several local  landscape companies that have completed the fire-wise defensible space landscape course will inspect your property and home and provide you with a complimentary prescription plan addressing hazard mitigation and planning process to make your home and property fire wise.  These landscape companies possess a stronger fire wise skill set than those that have not taken the course. PREPARE, PROTECT and BEWARE.  Call the Fire Department at (928) 771-1700 to schedule an inspection or call YCCA to schedule a landscape review.  The University of Arizona Cooperative Extension has a great web site for information on fire wise and watersmart plants for the Prescott area.

It is important to remember that in a wildfire if firefighters determine that your home is NOT defensible they may, in the interest of their safety, NOT attempt to save it.  Let’s have a safe and uneventful fire season.

Phone: (928) 778-0040


810 E. Sheldon Street, Prescott, AZ 86301

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