Leaf burn times of California native plants

California Plants and Fire

There are decades of conflicting information about the flammability of native plants. The fear of fire and the abundance of misinformation about native plants has resulted in wildlands (and their wildlife) being replaced with more flammable landscape materials. After 30 years of experience with California native plants in their natural environment, (and fourteen years as a firefighter) we have developed a simple method to compare the flammability of native plants. The experiment is simple, fair, and repeatable, with relevance for firefighters, designers, and homeowners.

In a two week period of September of 2005, temperatures were in the 90's and the humidity was about 30%. Leaves (or clusters as they were on stem) of various plant species were tested for ignition times until two numbers were the same within a few seconds. If after five tries(boring!), numbers were still divergent, numbers were either listed as a range or averaged if all over the place. Most plants tested were field grown and had not been watered all summer (exceptions noted in table below). Every effort was made to duplicate (or worse) a dry coastal garden under water rationing.

Garden watered plants should be considerably harder to ignite if watered as little as fifteen minutes once every two weeks, BUT, not always. However, the worst fires I've seen are at the end of a drought cycle when there is no water to even fight the fire, never mind water the plants. (For those of you back east, it is similar to putting the plant in a convection oven set at 130 degrees for a month.)


Native plants did not burn that well.
Flame applied to leaf. Notice it is not bursting into flame.

Big leaf maple leaf after being torched with a blow torch flame..Many of the leaves never even glowed.

If you live in town and have a twenty foot front yard, ignore this list. This is primarily for those of you in rural residential areas, at the worst with a poor well, thirty minutes from the nearest fire engine and are gone a lot. The designers that are planning an urban interface should find this useful also.

Using a propane torch with a one centimeter length flame (+/- 1mm), the blue tip of flame was placed on to a leaf, if leaves large, or first leaf cluster if leaves small, until the leaves ignited and held a flame longer than five seconds. Some leaves would flash. If they held a flame or carried to other leaves that was counted. Some blacked and never ignited, some never even glowed, and others ignited easily. At first the tests were done on the plants themselves, but that proved too exciting and the slightest breeze altered the results (and had potential for even more excitement). I settled on collecting a few stems of a few plants and testing those in a closed barn within minutes of collection. Results were not what I'd had heard or read, and often not what I expected. Generally, (and boy are there inconsistencies,) the more drought tolerant the plant, the poorer it burns, the smaller the leaf, the poorer it burns, and the wider spaced leaves are very hard to ignite. For the most part, un-watered natives did better than watered non-natives.
Good mulch is an important component of California's gardens/landscapes and ecology. The moisture that mulch retains helps keep the plant material hydrated and a little less flammable. Mulch (shredded redwood bark or shredded cedar bark) does burn, and creeps along with a smoldering fire that can be kicked or raked out. This type of mulch burns with a lot of smoke, little flame. A pile of dead leaves, twigs and sticks does not burn in the same way. Think of the comparison like a newspaper laid flat on the ground versus each page wadded up into a pile. The worst situation is when you have flashy fuels like dead grass running up into either taller weeds, dead leaves of garden plants or some of the native plants.

This experiment really points out that weed control and garden hygiene are as important, or more important, than plant choice or irrigation practices.

Genus

Species

Variety

Cultivar

live ignition (seconds)

dead leaf ignition (seconds)

notes

Abies

bracteata

>60


Acacia

greggii

>60


one weak flash

Acer

circinatum

15


Acer

macrophyllum

>60


Acer

negundo

californicum

30

1

Achillea

millefolium

californica

5

1

six inch flame height

Achillea

millefolium

rosea

Island Pink

>60

1

Adenostoma

fasciculatum

30


dried seed heads -1 second.

Adiantum

jordanii

>60


Aesculus

californica

>60


Agrostis

pallens

>60


a lot of dead grass, but the green leaves extinguished the dead ones

Alnus

rhombifolia

15


Ambrosia

psilostachya

>60


Anaphalis

margaritacea

>60


Anemopsis

californica

>60


leaves develop water blisters

Aquilegia

eximia

no fuel


Aquilegia

formosa

no fuel


Aquilegia

pubescens

no fuel


Aquilegia

shockleyi

no fuel


Arbutus

menziesii

>60

15

Manzanitas are all over the chart and do not appear to change when watered.

Arctostaphylos

Baby Bear Manzanita Bush

>60


Arctostaphylos

Ian Bush Manzanita

10


watered ones were also 10

Arctostaphylos

John Dourley

45


watered sample

Arctostaphylos

Mama Bear Manzanita

7


Arctostaphylos

Margarita Pearl

30


Arctostaphylos

Pacific Mist

30


Arctostaphylos

densiflora

Harmony Manzanita

>60


Arctostaphylos

densiflora

Howard McMinn Manzanita

15


watered sample was 30

Arctostaphylos

densiflora

Sentinel Manzanita

>60


Arctostaphylos

edmundsii

Big Sur Manzanita

20


Arctostaphylos

edmundsii

Carmel Sur Manzanita

30


Arctostaphylos

glandulosa

adamsii

5


Arctostaphylos

glandulosa

glandulosa

10


Arctostaphylos

glandulosa

howellii

10-20


Arctostaphylos

glandulosa

ssp.crassifolia

Del Mar Manzanita

>60


Arctostaphylos

glandulosa

zacaensis

San Marcos Manzanita

10


Arctostaphylos

glauca

20


Arctostaphylos

glauca

Ramona Manzanita

50


Arctostaphylos

hookeri

Wayside Manzanita

>60


watered sample

Arctostaphylos

hookeri

franciscana

Franciscana Manzanita

7


extreme drought -7 secs. watered- 7 secs., but it sure looks better

Arctostaphylos

hookerii X pajaroensis

Sunset Manzanita

>60


Arctostaphylos

insularis

7


Arctostaphylos

manzanita

Dr. Hurd Manzanita Tree

15


Arctostaphylos

manzanita

Real manzanita

>60


watered sample

Arctostaphylos

manzanita_x_densiflora

Austin Griffiths Manzanita

45


watered plants easier to ignite than dry land ones?

Arctostaphylos

mariposa

>60


even charcoal wouldn't ignite after 90 secs.

Arctostaphylos

morroensis

Park View Manzanita

12


Arctostaphylos

obispoensis

San Luis Obispo Manzanita

15

3

Arctostaphylos

pajaroensis

Paradise Manzanita

7


Arctostaphylos

parryana

Snow Lodge Manzanita

20

1

Arctostaphylos

patula

12


Arctostaphylos

pechoensis

5


Arctostaphylos

pilosula

pilosula

Atascadero Manzanita

5


Arctostaphylos

pungens

30


Arctostaphylos

purissima

Burton Mesa Groundcover

15


Arctostaphylos

refugioensis

Refugio Manzanita

15

1

Arctostaphylos

rudis

7


Arctostaphylos

silvicola

Ghostly Manzanita

12


Arctostaphylos

standfordiana

10


Arctostaphylos

stanfordiana

bakeri

Louis Edmunds Manzanita

15


Arctostaphylos

uva-ursi

Point Reyes Manzanita

>60


watered sample

Arctostaphylos

uva-ursi

Radiant Manzanita

15


watered sample

Arctostaphylos

uva-ursi

suborbiculata

San Bruno

>60


watered sample

Arctostaphylos

viridissima

>60


Arctostaphylos

viscida

ssp. viscida

15


regularly watered sample- 15 secs.

Arctostaphylos

wellsii

Wells Manzanita

20


Argemone

munita


Aristolochia

californica

Sierra Giant Pipe Vine

>60


Artemisia

californica

>60

1

'melted' down to dead/dry leaves then burned after 60 secs.

Artemisia

californica

Canyon Gray

Canyon Grey

>60

1

Artemisia

californicaX

Montara

Montara

>60

1

dead material difficult to extinguish

Artemisia

douglasiana

15


Artemisia

ludoviciana

ludoviciana

>60

10

Artemisia

tridentata

>60


watered sample - >60 secs.

Asclepias

eriocarpa

>60


Asclepias

fascicularis

>60


Asclepias

speciosa

55

3

no flame after 5 secs., had to work to light

Aster

ascendens

>60


one ignited at 45 secs.

Atriplex

canescens

>60


Atriplex

lentiformis

Breweri

>60


Baccharis

douglasii

>60


will not sustain flame

Baccharis

pilularis

consanguinea

25


varied from 12 to >60 secs. on very old plant

Baccharis

pilularis

pilularis

Pigeon Point

>60


used dry, unwatered plant

Baccharis

pilularis

pilularis

Santa Ana

>60


Baccharis

pilularis

pilularis

Twin Peaks


Baccharis

viminea

>60


Brickellia

californica

>60

1

if leaves clustered, can be burnt

Calliandra

eriophylla


Calycanthus

occidentalis

>60

>60

will not stay lit

Camissonia

cheiranthifolia

ssp. suffruticosa

>60


Carex

globosa

>60


Carex

praegracilis

15


summer deciduous

Carex

sartwelliana

>60


Carex

spissa

>60


Carpenteria

californica

>50


one in four tries was able to get leaf to burn

Ceanothus species are relatively hard to burn and respond well to light overhead watering once every two weeks. A dust- off once every two weeks makes them really hard to burn.

Ceanothus

Blue Jeans

>60


Ceanothus

Celestial Blue

>60


Ceanothus

Concha

>60


Ceanothus

Frosty Blue

30


very drought stressed watered sample = >60

Ceanothus

Joyce Coulter

>60


Ceanothus

Julia Phelps

>60


Ceanothus

L.T.Blue

>60


sparse foliage difficult to light

Ceanothus

Mills Glory

45


>60

Ceanothus

Mountain Haze

>60

15

Ceanothus

Ray Hartman

>60


Ceanothus

Remote Blue Ceanothus

>60

2

Ceanothus

Tassajara Blue Ceanothus

45


watered sample

Ceanothus

Wheeler Canyon

>>60


Ceanothus

arboreus

20


watered sample = >60

Ceanothus

arboreus

Owlswood Blue

>60


melted leaves will not ignite

Ceanothus

crassifolius

15


Ceanothus

cuneatus

25


Ceanothus

cuneatus

Sierra mt. lilac

50


Ceanothus

cyaneus

>60


Ceanothus

cyaneus

Sierra Blue Ceanothus

10-30


leaves roll and ignite

Ceanothus

gloriosus

Hearts Desire

>60


Ceanothus

gloriosus

porrectus

>60


Ceanothus

griseus

horizontalis

Yankee Point

>60

50

looked like it would burn

Ceanothus

hearstiorum

>15


with regular watering = >60

Ceanothus

impressus

impressus

50


flame held just 5 secs. on unwatered plant

Ceanothus

impressus

nipomoensis

>60


Ceanothus

maritimus

30


Ceanothus

megacarpusX

Tranquil Margarita

55


Ceanothus

oliganthus

oliganthus

>60


Ceanothus

prostratus

>60


Ceanothus

ramulosus

fascicularis

7


Ceanothus

rigidus

Snowball

>60


Ceanothus

sorediatus

Klamath

>60


Ceanothus

spinosus

>90


Ceanothus

thyrsiflorus

Big Sur California lilac

>60


Ceanothus

thyrsiflorus

Skylark

>60


Ceanothus

thyrsiflorus

repens

>60


Ceanothus

tomentosus

>60


one leaf burnt out of six

Ceanothus

verrucosus

75


kept getting just over 60 secs.

Cephalanthus

occidentalis

californica

40


watered sample = >60

Cercidium

floridum

>60


Cercis

occidentalis

>60


Cercocarpus

alnifolius

>60


did light once in six tries

Cercocarpus

betuloides

50


mostly >60 secs., some ignition

Chamaebatia

foliolosa


Chilopsis

linearis

>60


Chrysothamnus

nauseosus

>60

10

Clematis

ligusticifolia

>60


Comarostaphylis

diversifolia

15


leaves rolled and ignited

Corethrogyne

filaginifolia

>60


Cornus

glabrata

15


Cornus

stolonifera

7


Corylus

cornuta

californica

10


only lights 50% of time, vaporizes then

Crataegus

douglasii

>60


Cupressus

forbesii

>60


Cupressus

nevadensis

15


Dendromecon

rigida

>60

1

prune to ground every 3-5 years

Diplacus

aurantiacus

Sierra monkey flower

>60


watered sample

Diplacus

aurantiacus

australis

Ramona

>60

deciduous, 5

need to tidy!

Diplacus

aurantiacus

lompocensis

Vandenberg Monkey Flower

30


old flower/capsules burn

Diplacus

grandiflorus

3

1

need to tidy!

Diplacus

longiflorus

>60


at water's edge

Diplacus

longiflorus

Conejo monkey flower

3


seed capsules ignite watered and trimmed sample = >60

Diplacus

puniceus

Otay monkey flower

3


dead-heading would fix

Diplacus

rutilus

>60


water sample

Dudleya

pulverulenta

3

Elymus

condensatus

>60


Encelia

californica

>60

1

Encelia

farinosa

>60


Epilobium

angustifolium


Epipactis

gigantea

45


Ericameria

arborescens

>60


Ericameria

ericoides

>60


Erigeron

Wayne Roderick Daisy

>60


Erigeron

glaucus

>60

1

Erigeron

glaucus

Cape Sebastian

>60

1

Eriodictyon

angustifolium (californicum)

40- >60


very variable

Eriodictyon

crassifolium

20


Eriodictyon

tomentosum

20

5

Eriogonum

arborescens

>60


foliage was non-flammable

Eriogonum

fasciculatum

foliolosum

>60

1

Eriogonum

fasciculatum

polifolium

>60


similar to lavender

Eriogonum

giganteum

>60

>60

Eriogonum

grande

rubescens

>60


Eriogonum

parvifolium

>60


Eriogonum

umbellatum

10


dead leaves are a problem

Eriogonum

umbellatum

polyanthum

Shasta Buckwheat

50


turns to charcoal and burns

Eriogonum

wrighti

subscaposum

>60


Eriophyllum

confertiflorum

2


took 3 tries to carry flame

Eriophyllum

staechadifolium

artemisiaefolium

>60


Fallugia

paradoxa

>60


Ferocactus

acanthodes

cholla

3


spines burn good!

Fragaria

californica

>60


nothing left after 20 secs.

Fragaria

chiloensis

>60


occasionally lit, but no live coals

Fraxinus

dipetala

10


Fraxinus

latifolia X velutina

>60


Fremontodendron

Ken Taylor

20

15

Fremontodendron

Pacific Sunset

15


Fremontodendron

californicum

>60


Fremontodendron

californicum

decumbens

>60


Garrya

elliptica

James Roof

15


Garrya

flavescens

pallida

20

3

Garrya

veatchii

15

3

Grindelia

camporum

>60


Haplopappus

squarrosus

>60

1

Haplopappus

venetus

vernoniodes

>60


Heleniun

hoopesii

>60


Heleocharis

parishii

>60


Helianthemum

scoparium

>60


Heteromeles

arbutifolia

50


burn out moisture to burn leaf

Heterotheca

grandiflora


Heuchera

maxima

>60


blew holes in leaves

Holodiscus

discolor

5

1

Horkelia

cuneata

>60


Horkelia

parryi

>60


Isomeris

arborea


Iva

hayesiana

>60

>60

Juglans

hindsii

>60


leaves melt, flash, flame dies

Juncus

patens

>60


Juniperus

californica

>60


Juniperus

communis

montana

>60


burned creeping, smouldering, slowly

Keckiella

antirrhinoides

>60

1

Keckiella

breviflora

>60

1

Keckiella

ternata

septentrionalis

>60

3

tidy, if summer deciduous

Larrea

tridentata

>60


low flammability

Lepechinia

fragrans

>60


smokes a lot

Leptodactylon

californicum

1 sec.


Libocedrus

decurrens

30


Lithocarpus

densiflorus

15


Lobelia

cardinalis

>60


Lobelia

dunnii

serrata

>60


appears non-flammable

Lonicera

hispidula

45

5

watered sample = >60

Lonicera

interrupta

10


Lonicera

subspicata

denudata

15


Lotus

scoparius

>60

3

if untrimmed = 3 seconds

Lupinus

albifrons

60


Lupinus

excubitus

>60


'melts into black mass'

Lyonothamnus

floribundus

ssp. asplenifolius

30


Mahonia

aquifolium

Compacta

>50


burns as leaves dry out

Mahonia

Higginisii

10


Mahonia

nevinii

20-50


leaves burned a second, then went out

Mahonia

pinnata

10


Mahonia

repens

20

3

Malacothamnus

fasciculatus

>60


Malacothamnus

marrubioides

25

1

Malacothamnus

palmeri

involucratus

45


smells like cow chips

Maurandya

antirrhiniflora

>60


Mimulus

cardinalis

>60


Mimulus

guttatus

>60


Monardella

antonina

>60


Monardella

linoides

stricta

>15


Monardella

macrantha

>60


Monardella

villosa

10


flashes, then dies

Monardella

virides

15


Muhlenbergia

rigens

3


slow, like straw broom

Myrica

californica

15-40


watered sample = very inconsistent

Oenothera

caespitosa

marginata


Oenothera

hookeri

>60


no coal embers

Ornithostaphylos

oppositifolia

30


Penstemon

Margarita BOP

<60

2

tidy dead leaves

Penstemon

eatonii

>60


Penstemon

grinnellii

10


very dry plant

Penstemon

heterophyllus

heterophyllus

>60


Penstemon

incertus

10


Penstemon

newberryi

>60


nothing left of plant

Penstemon

spectabilis

20-30


Philadelphus

lewisii

>60


lit once in 5 tries

Physocarpus

capitatus

5

1

low to moderate fuel load

Pickeringia

montana

>60


Pinus

attenuata

15


Pinus

flexilis

20


Pinus

jeffreyi

40


Pinus

monophylla

45


Pinus

muricata

>60

1

live leaves fall off instead of igniting

Pinus

ponderosa

>60


lit once in 10 tries

Pinus

sabiniana

45

3

Platanus

racemosa

>.60


kinda burned at 60 secs., if leaves rolled right and the angle was right

Pluchera

odorata

odorata

>60


not even coal

Populus

fremontii

60

1

dead leaves burn very well

Populus

tremuloides

5


poof!

Populus

trichocarpa

30

1

Potentilla

glandulosa

>60


Prosopis

glandulosa

torreyana

15


Prosopis

pubescens

>60


Prunus

ilicifolia

7


Prunus

lyonii

45

2

Prunus

virginiana

demissa

20


Prunus

virginiana

melanocarpa

avg 40


ignited twice in 5 tries

Pseudotsuga

menziesii

40


Psoralea

orbicularis

>60


Ptelea

crenulata

25

1

Pteridium

aquilinum

pubescens

>60

1

Purshia

glandulosa

50


unwatered and very dry

Purshia

tridentata

>60


Pycnanthemum

californicum

30-60


Oaks are pretty flammable, but with management are not a problem. Do not run out and cut all your oaks down, but do make sure there are no weeds or upright twiggy dead debris under them and prune the limbs up so you can walk under them.

Quercus

agrifolia

10 sec.


watered sample = 10 seconds

Quercus

berberidifolia

20


Quercus

chrysolepis

5


Quercus

douglasii

>60


I have no idea, tried repeatedly

Quercus

engelmannii

7


Quercus

garryana

breweri

15

10

Quercus

kelloggii

10


Quercus

lobata

avg 15


Quercus

tomentella

25

2

Quercus

wislizenii

5


watered sample

Rhamnus

californica

>60


smoulder only

Rhamnus

californica

San Bruno

30


with some watering = >60

Rhamnus

californica

Eve Case

>60


will not sustain ignition

Rhamnus

californica

Tranquil Margarita

>60


Rhamnus

crocea

>60


both watered and unwatered didn't light

Rhamnus

crocea

ilicifolia

15


bigger leaves burn more easily?

Rhus

integrifolia

>60


Rhus

laurina

>60


tried repeatedly, got one flash out of five+ tries suspect dead leaves for its reputation of being flammable, so tidy!

Rhus

ovata

>60


popped a lot

Rhus

trilobata

>60


Ribes

aureum

gracillimum

50

3

if dead leaves are allowed to pile up or linger, that can be a problem

Ribes

californicum

>60


Ribes

indecorum

>60

3

Ribes

malvaceum

>60


can burn in 30 seconds but doesn't carry flame

Ribes

menziesii

>60

3

Ribes

nevadense

30


poor ignition

Ribes

quercetorum

>60


Ribes

sanguineum

glutinosum

>60


Ribes

speciosum

>60

10

Ribes

viburnifolium

>60


vaporized to little ash

Romneya

coulteri

>60

1

Rosa

californica

>60


Rosa

gymnocarpa

>60


Rosa

pinetorum

>60


got one leaf to light, not repeatable

Rosa

woodsii

glabrata (mohavensis)

45


Rubus

parviflorus

45


Salix

laevigata

15


Salix

lasiolepis

10


Salvias are very flammable if you do not keep them clean and wash them down occasionally. Just washing the leaves off every two weeks and keeping them tidy is enough to make them almost fire proof.

Salvia

Bee's Bliss

10

5

tidy!

Salvia

Celestial Blue

12


very little fuel watered and trimmed = >60 secs.

Salvia

Daras Choice

50

3

Salvia

Gracias

10

3

tidy! watered sample = 40 secs.

Salvia

Pozo Blue

see notes


young leaves = 30 secs. old leaves = 15 secs. trimmed and watered = >60 secs.

Salvia

apiana

20


on edge of watered area = >60 secs.

Salvia

apiana

compacta

10


Salvia

brandegei

>60


very clean

Salvia

clevelandii

Alpine Cleveland sage

7-15


watered sample = >60 secs.

Salvia

clevelandii

Winifred Gilmam Cleveland Sage

15


watered = >60 secs., but erratic

Salvia

dorrii

>60


Salvia

leucophylla

12


Salvia

leucophylla

Pt. Sal

15


Salvia

mellifera

20


Salvia

mellifera

repens

>60


at edge of watered area

Salvia

munzii

>60


not even charcoal

Salvia

pachyphylla

>60


smells good!

Salvia

spathacea

15


summer deciduous, needs to be tidied. watered sample = >60 secs.

Salvia

spathacea

Powerline Pink

20


Salvia

spathecea

Las Pilitas

>60


Sambucus

caerulea

>60


Sambucus

mexicana

>60

1

keep tidy

Satureja

douglasii

>60


Satureja

mimuloides

10


Scrophularia

atrata

>60


Scrophularia

californica

>60


Scutellaria

austinae

>60


Sedum

oreganum

>60


water expelled from leaves

Senecio

douglasii

>60


leaves melted

Sequoia

sempervirens


Sisyrinchium

bellum

>60


watered sample

Sisyrinchium

californicum

>60


watered sample

Solanum

xanti

>60


smells like bad goat cheese

Solanum

xanti

hoffmannii

>60


old pig smell

Solidago

californica

>60


some unsustained ignition

Solidago

canadensis

elongata

7-15


Solidago

confinis

>60


Sphaeralcea

ambigua

30

3

need to tidy

Spiraea

douglasii

5


Stachys

ajugoides

rigida

Persnickety Pink

>60


Stachys

bullata

>60


Stachys

chamissonis

>60


Stanleya

pinnata

>60


Styrax

officinalis

fulvescens

7


watered sample

Symphoricarpos

albus

laevigatus

>60


Tellima

grandiflora

>60


Thalictrum

fendleri

>60

1

need to tidy!

Thuja

plicata

15


very oily

Toxicodendron

diversilobum

>60


held breath

Trichostema

lanatum

10


Trichostema

parishii

10


Umbellularia

californica

15


Vaccinium

ovatum

>60


foliage melted

Venegasia

carpesioides

>60

1

Vitis

californica

55

3

dead burning leaves go out after 5 secs.

Vitis

girdiana

>60


Wyethia

ovata

>60

1

Xylococcus

bicolor

45


varied from 15- 60+ secs.

Yucca

whipplei

percusa

>60


The California fuchsias are not flammable, but any of their debris is, mow them down every December of January and you should be fine.

Zauschneria

californica

Catalina

>60


Zauschneria

californica

Ghostly Red

>60

5

debris doesn't carry flame

Zauschneria

californica

Pink

>60


Zauschneria

californica

White

>60


Zauschneria

californica

Uvas Canyon

>60


Zauschneria

californica

mexicana

>60

10

Zauschneria

cana

>60


Zauschneria

latifolia

johnstonii

>60

15

Zauschneria

latifolia

viscosa

>60


Zauschneria

septentrionalis

Mattole River

>60

5


Non-Native Grasses and Weeds

The numbers explain why brush fires slowly spread in comparison to grass/weed fires. Grass/weed fires can kill you.. If you look at it this way, (and there are no absolutes in nature), when a field is in annual grass and mustard, and the ignition time per plant is almost instantaneous, you'll get what appears to be area ignition. You can't outrun something that basically blows up. Brush burns at, on average, 45 seconds per plant and makes a very hot creeping fire,(with some dramatic flashes); you can't be within one hundred feet of it and be comfortable, but you can usually move to one side or the other. In contrast, if you have weeds in brush, you get a very fast, erratic, spotty, and hot fire that's like playing with a poisonous snake.
In fire training one of the points they drilled into the concrete of our heads was, ���firemen rarely die in brush fires...all the recent deaths in California have been in grass related fires���.


Annual grass (Bromus diandrus)

dead since May

instant, so fast impossible to time. Whole plant gone in a second.

weed control is very important

Melilotus

2



Mustard

3



Star Thistle (Centaurea solstitialis)


2






Typical non-native landscape plants. These are not NATIVE!

Plant

leaf ignition (in seconds)

dead leaf ignition (in seconds)

Notes (times in seconds)

Abelia

30


watered planter in Atascadero, California

Apple, Improved Pippin

30-60

2

very variable, this one was watered regularly, -under drought, is flammable

Blackberry

50-60


regular water

Bottle bush

12



Bottle Tree

>60


regular water

Buddleja davidi ('Butterfly bush')

5


very flammable in watered greenhouse

Cistus villosa

new growth 45, old growth 10


watered planter in Atascadero, California

Cotoneaster, groundcover

>60


watered sample from SLO

Cotoneaster, shrub

10


watered sample from SLO

Day Lilly

>60



Elm, Chinese

30


watered sample from SLO

Eucalyptus, Red Flowering Gum

15



Eucalyptus, Red Gum

5


watered sample from SLO

Gamolepis daisy

>60


watered planter in Atascadero, California

Gazania

>60



Grape, Thompson Seedless

>60

3

hygiene is important

Ivy, Algerian

20



Juniper, Pfitzer

15



Lavender, English

20


dead stuff lights easily

Lavender, Hidcote

20

1

dead stuff lights easily

Lavender, Munstead

>60

1

dead stuff lights easily

Lavender, Spanish

>60

1

live foliage with breeze = >30 dead stuff lights easily

Lemon Verbena

5


some of the tropical stuff ignites readily

Lilac, common

3


plant was very dry, I've seen similar in dry gardens

Myoporum parvifolium

>60


watered sample from SLO

Nandina

10


watered planter in Atascadero, California

Oleander

10



Peach, Elberta

45


regular water

Pear

20


very lush and regularly watered.

Persimmon

>60


looked lush and had regular water

Pittosporum Tobira

7



Plum, Santa Rosa

15


looked lush and had regular water

Quince, Pineapple

30


looked lush and had regular water

Raphiolepis sp.

12


watered planter in Atascadero, California - popped and snapped

Thyme (Thymus sp.)

<60




Mulch

time to ignite for sustained 5 seconds

dry Chipped Cedar leaves

1 sec. -flame height six inches

dry Redwood shavings

1 sec. -flame height one inch

dry Oak and Pine chips

10 secs.- flame height one inch pieces too large and random to lay flat

dry Shredded redwood bark

loosely laid single grind = 15 secs.- flame height 3 inches properly laid single grind = 20-30 secs.- flame height one inch (the sticks ignite) loosely laid double grind = 15 secs.- flame height 2 inches properly laid double grind = 60 secs.- flame height one inch mulch needs to lay flat and compact with no twigs or debris (a heavy watering at application will help accomplish this)



Materials. Don't forget the fence, deck and siding.

Material

time to ignite for sustained 5 seconds

1X cedar board

35 seconds

daily newspaper laid flat

5 seconds

cardboard

1 second

stained 1X pine

5 seconds

1X redwood

50-60 seconds

1X linseed treated (cured) redwood

10 seconds

9/16 plywood

30 seconds

1X4 and 2X4 doug fir

30 seconds



Back in the 1980's during the Chispa fire we (volunteer and paid firefighters) were back-firing into the main fire to stop it. We could not light the brush; the torch made a fire ball in the bush, and it would go out and not stay lit. After about thirty minutes of this frustration (hey, we were exhausted and a little slow) we figured out that if we looked for weeds (mostly annual grasses), we could light them and they would light the brush. That worked!