Transforming a Fire-Resistant Green Roof: 5 Plants to Foster, Safeguarding Your Home from Wildfire Destruction
Going green doesn't always mean turning eco-friendly. In the sultry southwestern US, the term can also mean employing green roofs to safeguard homes and businesses against wildfires. A hail of flames is becoming a regular sight in these sun-baked states, and property owners and specialists alike are brainstorming ways to beef up property protection. The spotlight falls increasingly on the planting movement for green, living roofs.
Could this popular landscaping detail save us from the wrath of wildfires, and what are the best fire-resistant plants to use? We dive into this fascinating topic, enlisting the help of top landscaping experts.
Can a green roof protect from wildfire damage?
The usefulness of green or living roofs in warding off wildfire damage remains a topic of heated debate. While no certified living roof system has been guaranteed to ward off a forest or wildfire, there are discussions about the flammability and fire retardancy of the substrates and membranes used, as well as the incendiary characteristics of the chosen plants for a green roof.
Award-winning landscape and architectural design specialists Browning Day comment that 'most grasses will propagate flame spread and may present a legitimate fire safety concern under perpetual drought conditions.' Yet, there's plenty of reputable research verifying that green sedum roofs (or stonecrops) and other succulents are naturally flame-resistant and won't contribute to the spread of fire any more than a conventional low-sloped roof assembly.
What are the best plants for a fire-resistant green roof?
Plant selection plays a significant role when designing a fire-resistant green roof. Green roof specialist, Oscar Warmerdam, CEO of Sempergreen USA, advises avoiding vegetation that retains significant biomass throughout winter, as dormant plants with dry, brown foliage can become fuel for airborne embers. Instead, opt for species that either maintain moisture year-round or shed their biomass in a way that minimizes fire risk.
Green roofs protect from wildfire when made up of the plants Oscar describes, such as landscaping with succulents and cacti: 'Drought-tolerant succulents, commonly chosen for their resilience, do not accumulate combustible material. Their high-water content prevents ignition, and in the presence of fire, they simply shrink rather than burn,' explains Oscar.
Typically featured in extensive green roofs, these designs have a shallow soil profile and require plant varieties that need very little maintenance. 'These roofs require little to no irrigation in much of the northern US, making them a low-maintenance option,' continues Oscar. 'Their composition naturally resists fire, as embers landing on the surface simply die out, unable to ignite the fire-resistant soil.'
Drought-tolerant sedum, also known as stonecrop, is one of the best xeriscaping plants, suitable for an extensive living roof. There are over 600 hundred known sedum varieties, but only a handful are resilient enough to thrive when planted on a roof. Adept at storing water in their leaves, these plants can handle the ever-varying weather conditions and require few nutrients, sun, and rainwater.
You can find a range of sedum plants available at Nature Hills. Below, we take a look at some of the best fire-resistant plants for a green roof, as recommended by the experts:
- White stonecrop (Sedum album): This native species is incredibly drought-tolerant and a real sun-lover. Shallow rooting, it grows laterally, producing a mass of tiny jellybean-like leaves that are apple green for most of the year, turning rust red in fall. White starry blooms appear in summer, making it a great plant for pollinators.
- Goldmoss stonecrop (Sedum acre): As a fast-growing succulent to plant outdoors and with shallow roots, Sedum acre, also known as Biting stonecrop, is an obvious choice for any living roof. Tough, sun-loving, and able to cope with fluctuating temperatures and sporadic rainfall, it is also one of the hardest plants to kill.
- Calcareous houseleek (Sempervivum calcareum): Particularly heat and drought-tolerant, thanks to its plump foliage, this variety of hens and chicks, sempervivum calcareum, is hardy in US hardiness zones 4 to 9. With tight rosettes of waxy leaves, these fascinating one-inch-high plants form dense vegetative mats with the baby plants radiating out from a central parent.
- Jade plant (Crassula ovata): Well-known as a sculptural houseplant in the Northern hemisphere, crassula ovata is a relatively fast-growing succulent with many different varieties, varying from 78-inch tall shrubs to sprawling ground huggers growing no more than 35 inches tall. With fleshy tube-shaped foliage, these succulents naturally store water, making them highly heat-resistant.
- Ice plant (Delosperma): Speedy to grow and fascinating to look at, Delosperma quickly forms a dense, low-growing carpet of glaucous foliage smothered with brilliant pink, purple, and yellow daisy-like flowers every summer. Hardy in US hardiness zones 5 to 9, this plant will grow between six and eight inches tall, thriving in free-draining soil and ideally receiving between six to eight hours of sun per day. It will tolerate some shade but prefers full sun. Butterflies adore the blooms in summer, especially the bright hues like the magenta of 'Orchid Flash' ice plant.
- Green roofs can be fire-resistant when composed of plants such as succulents and cacti due to their high water content and inability to ignite easily.
- Some of the best fire-resistant plants for a green roof include White stonecrop (Sedum album), Goldmoss stonecrop (Sedum acre), Calcareous houseleek (Sempervivum calcareum), Jade plant (Crassula ovata), and Ice plant (Delosperma), which are all drought-tolerant and heat-resistant.
