Plants That Are Quietly Increasing Fire Risk in American Gardens – And What To Choose Instead
Opting for fire-wise plant choices can make a dramatic difference in reducing risk in vulnerable regions
Growing trees and plants in our gardens is an important endeavour; not only are they beautiful in the landscape, they create shade, reduce the temperature on hot days and can provide a haven for wildlife.
However, for those who live in drought-prone or arid areas where wildfires are a risk, plant choice matters. Opting for certain species over others can make a significant difference in either increasing or decreasing safety.
Design and layout are important factors too, and many are turning to firescaping their gardens: zoning areas, removing flammable materials and increasing maintenance to make their properties more fire resistant. When it comes to knowing what to grow, we've asked the professionals what plants, shrubs and trees to avoid and which to choose instead to reduce risk.
'Certain characteristics increase the flammability risk of plants,' explains Brooke Addison, landscape designer & founder, Lark Haven Studio. 'These include being woody, having low moisture content, containing volatile oils or resins, having papery bark, and retaining high amounts of dead plant material.
'On the other hand, indicators of low flammability are high moisture content, watery sap, low wood levels (i.e. herbaceous) and minimal dead plant material. While there may be exceptions, this is a good rule of thumb when analyzing plants for flammability.'
Brooke Addison is a landscape designer and founder of Lark Haven Studio. Based in Seattle, she works on projects as far as California and Florida. She holds certificates in Sustainable Landscaping, Permaculture and in Wildfire Defense for Landscape Professionals from the U.S. Green Building Council California.
1. Italian Cypress (Cupressus sempervirens)
Italian Cypress trees might look beautiful with their tall, slender shapes and evergreen foliage, but in drought-prone, arid areas, this is an example of a species that is best avoided due to its flammability.
'Because of its tall, slim shape, Italian Cypress is often used to frame entrances or add vertical interest,' says Arizona-based horticulturalist and landscape consultant, Noelle Johnson, aka The A-Z Plant Lady.
'However, it is highly flammable due to its resinous foliage and dense branches. When planted in rows, it can create a chimney effect, rapidly spreading and intensifying fire.
'Podocarpus (Podocarpus macrophyllus) offers a similar upright form but with broadleaf evergreen foliage that typically holds more moisture than conifers, making it safer in fire-prone areas. It provides privacy and structure year-round with low maintenance needs.'
This Podocarpus from Plant Addicts grows to around 10-15' high and 3-4' wide in zones 7-10.
Noelle is a horticulturist, landscape consultant, and garden writer who lives in the Phoenix, Arizona metro area. Popularly known as the 'AZ Plant Lady,' for over 20 years her passion has been to inspire and teach people to create, grow, and maintain beautiful gardens that thrive in a hot, dry climate.
2. Pines and Spruces
These attractive species are often used as privacy screens around property lines. However, pines and spruces fall into the same category as Cypress, they're conifers, and as such are evergreen trees never to grow in a fire risk zone.
'Conifers such as Cypress, Cedar, Fir, Junipers, Pines, and Spruces all contain high amounts of flammable resin,' explains Brooke. 'They also contain a lot of dead branches and leaves closer to the trunk, that we may not see because they're evergreen species. You don't want a giant sparkler next to your house.
'Pass on conifers and consider a deciduous tree instead. These tend to be less flammable. Remember to avoid trees with peeling, papery bark - they're so beautiful but so burnable. Moisture-loving plants burn more slowly, so willows, maple trees and redbuds would be a more suitable option.'
It's important to remember, there's no such thing as a fire-proof plant. 'If exposed to enough heat, all plants will burn,' says Brooke. 'However, we can utilize fire-resistant strategies in our gardens to increase resilience and safety.'
This Forest Pansy Redbud Tree from Nature Hill's is deciduous, suitable for zones 5-9 and likes full sun to partial shade.
'If you really want an evergreen option, you could go with Toyon (Heteromeles arbutifolia) or Lemonade Berry (Rhus integrifolia),' says Brooke. 'They're technically shrubs, but can grow up to 30 feet tall and be trained into a tree-like shape.'
These plants have leathery leaves, a high moisture content, and low amounts of resin and oils. So are a safer option.
'Fruit trees are also a good replacement, because they have a high moisture requirement and receive consistent water, making them less flammable,' adds Brooke. 'I prefer to use native plants because they're acclimated to the local conditions and are usually easier to care for.'
This Contender Peach Tree from Nature Hill's is cold hardy, has beautiful fall foliage and can be grown in zones 4-8. For a drought-tolerant, fruit tree, try this Olympian Fig from Burpee. It's hardy to 0ºF and suited to north-west summers.
If these suggestions don't apply to your region, you can still use the same concepts to find the right native plant for you.
3. Lavender (Lavandula)
This aromatic, Mediterranean plant may come as a surprise to many people, as it's generally drought-tolerant and suitable for dry gardens. However, it's not a wise choice if you live in a fire-prone region, particularly if it's planted close to your property.
'Fire-resistant plant lists are torn on Lavender,' explains Brooke. 'But it goes in the "No Go" category for me. It's a woody, volatile oil filled plant that you can't irrigate frequently.
'If you still want some pretty purple blue spires in your yard, consider Lupines, Penstemon, Camas (Camassia quamash), or Delphinium. These herbaceous perennials don't have woody branches and contain high moisture content, making them a safer choice.'
The Westcountry Blacksmith Lupine from Plant Addicts offers spectacular purple color. It thrives in full sun, but in hot southern regions, some light afternoon shade is appreciated.
This Dakota Burgundy Penstemon from Nature Hill's is another dramatic plant, with pink flowers and burgundy foliage and drought-tolerant, once established.
4. Rosemary (Salvia rosmarinus)
A popular culinary herb, Rosemary is another potentially risky plant in hot, dry zones, for the same reasons as Lavender. 'Mediterranean plants like Rosemary and Lavender can die if they have wet feet, so they are not good options near your home,' explains Brooke. 'They will resent being irrigated and they contain very flammable oils.
'The oils make the plants smell nice, so people tend to place them close to their homes, which is exactly what we don't want.'
Noelle says many are surprised that this herb can be flammable, but explains that large rosemary bushes near homes or patios can ignite quickly during drought or extreme heat. She reiterates that it's its aromatic oils, which give it a strong scent, that are highly combustible.
'A good alternative is Bush Germander (Teucrium fruticans),' says Noelle. 'With silvery leaves and soft lavender-blue flowers, bush germander has a similar rounded shape but lacks the highly flammable oils found in rosemary. It is drought-tolerant and performs well in dry, hot climates.'
This Germander plant from Plant Addicts is suitable for zones 5-9 and will need regular watering until its established. Keep plants irrigated with this heavy duty garden hose from Ace Hardware.
5. Hopbush (Dodonaea viscosa)
Popular in the Southwest, as a fast-growing, drought-tolerant screening shrub, hopbush is often used for privacy hedges. Yet this decorative plant is best avoided in fire-prone areas.
'Many don’t realize that hopbush can be a fire hazard,' sys Noelle. 'Especially when planted close together or when dead growth accumulates inside. Its oily foliage ignites easily and dense planting can create a fuel path for fire spread.
'Texas Ranger (Leucophyllum frutescens) offers similar drought resistance and evergreen screening but holds more moisture in its leaves. With proper care, it has a less flammable structure and adds attractive purple blooms during warm months.'
This Green Cloud Texas Sage from Fast-Growing Trees has silvery-gray foliage, pretty purple blooms and thrives in hot climates.
6. Oleander (Nerium oleander)
With its beautiful pink flowers – which range from the palest blush to deep cerise – Oleander is beloved in warm climates for tolerating heat, drought, and poor soils. Yet, this pretty plant is one to swap out for fire safety.
'While its toxicity is well-known, many don’t realize mature plants can also pose a fire risk,' says Noelle. 'Dense growth and internal dead wood can become heavy fuel, particularly if the shrub is drought-stressed or poorly pruned.
'Consider Orange Jubilee (Tecoma x 'Orange Jubilee') instead. It's a large flowering shrub that offers excellent screening with vibrant orange flowers and a more open growth habit, reducing flammable material inside the plant. It thrives in hot climates too.'
Suitable for zones 8-11, this Orange Tecoma from Plant Addicts has scented, trumpet-like flowers from spring to fall and attracts hummingbirds, butterflies and pollinators.
Choosing less combustible, more moisture-rich plants, shrubs and trees, and implementing fire-scaping ideas, can make a significant difference in slowing the spread of embers and flames and increase the safety of your home and your neighborhood.
'Fire wise design can still be beautiful design,' says Brooke. 'We just need to do some extra research and planning to keep our gardens and communities safe. By stacking different protective measures, we can optimize the protection of our homes from wildfire.'
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