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Acacia
Acacias were planted extensively across the Bay Area in the early 1900s for erosion control, windbreaks, and ornamental value, but many species have proven aggressively invasive and present serious fire risks. Blackwood acacia, Bailey acacia, and golden wattle are the most common problem species. Most Bay Area cities now discourage new acacia plantings, and many property owners face difficult decisions about managing existing mature stands.
How to Identify Acacia
- Blackwood acacia (A. melanoxylon): dark furrowed bark, lance-shaped phyllodes (flattened leaf stalks), 30 to 60 ft tall, most common problem species
- Bailey acacia (A. baileyana): fine blue-gray bipinnate foliage, bright yellow puffball flowers in winter, 20 to 30 ft, highly invasive seeder
- Golden wattle (A. longifolia): long narrow phyllodes, bright yellow rod-shaped flowers, 15 to 25 ft, aggressive coastal colonizer
- Green wattle (A. decurrens): fine bipinnate leaves, winged stems, yellow flowers, 30 to 50 ft, common in East Bay hills
- Most species produce masses of yellow flowers in late winter to early spring, often the first clue to their presence
- All species produce hard-coated seeds that persist in soil for decades, making eradication extremely difficult
Where It Grows in the Bay Area
Found throughout the Bay Area, particularly in disturbed areas, hillsides, and older neighborhoods. Blackwood acacia dominates in Oakland and Berkeley hills. Bailey acacia is widespread on the Peninsula. Golden wattle colonizes coastal areas in San Francisco and Mill Valley. Green wattle forms dense stands in East Bay open spaces near Piedmont and in Contra Costa hills.
Common Issues & Diseases
Acacias are among the highest fire-risk trees in the Bay Area. Volatile oils in foliage, retained dead branches, heavy leaf litter, and fast growth create extreme fire fuel loads. Acacia stands in the Oakland-Berkeley hills are a primary fire concern for both EBMUD and local fire departments.
Most Bay Area acacia species are listed as invasive by Cal-IPC. They outcompete native plants, form monocultures on hillsides, and produce seeds that remain viable in soil for 50+ years. Root sprouting after cutting makes removal difficult without follow-up treatment.
Acacias are short-lived and fast-growing, a dangerous combination. Wood is brittle, and large limbs regularly fail without warning, especially in wind. Root systems are shallow, and blowdowns during storms are common. Most species decline noticeably after 30 to 40 years.
Acacia pollen is a significant allergen for many Bay Area residents. The heavy winter-spring bloom period coincides with existing allergy season and can trigger severe reactions. The pollen travels on wind and affects residents well beyond the immediate property.
Bay Area Care Calendar
Season-by-season care guidance for acacia in the San Francisco Bay Area:
Peak flowering for most species, yellow puffball blooms make identification easy. Good time to assess which trees to keep versus remove before spring growth flush. Schedule removal work before nesting bird season.
Seed pods developing. Nesting bird season limits removal options March through August in many jurisdictions. If managing rather than removing, prune deadwood and thin canopy to reduce fire fuel load.
Fire season, ensure defensible space clearance. Remove all dead branches and excessive leaf litter beneath acacias. Thin canopy if in fire zone. Continue monitoring for root sprouts from previous removals.
Seeds dispersing. Pull seedlings before they establish deep roots. Post-fire season assessment, plan winter removal work. Cut stump treatments for removed trees should be inspected for regrowth.
Detailed Notes
Fire Risk Specifics
Acacias burn fast and hot due to volatile oils in the foliage and bark. In the 1991 Oakland-Berkeley Hills fire, acacia and eucalyptus stands contributed significantly to fire spread. If you live in a wildland-urban interface area with acacia on your property, fire departments strongly recommend removal or at minimum aggressive fuel reduction through pruning, litter removal, and understory clearing.
Removal Challenges
Acacia removal requires planning. Most species resprout vigorously from stumps and roots unless properly treated. Cut stump herbicide application immediately after felling (within 5 minutes) is the standard approach. The soil seed bank persists for decades, so follow-up seedling removal is needed for 5 to 10 years after initial clearing.
City Ordinance Treatment
Acacia treatment varies by city. Atherton exempts Bailey, green wattle and black acacia at any size (Ord. 679), and San Carlos excludes the same species. Belmont still requires a permit for acacias but issues it automatically. Woodside requires a Tree Destruction Permit but charges no fee for acacia removal. Oakland protects acacia at 9" DBH like any non-exempt species; Berkeley regulates only coast live oak on private land. San Rafael's fire code requires removal of acacia within 5 to 30 feet of structures. Most other cities apply their general size threshold. Check the city page before removing.
Arborist Pro Tips
Frequently Asked Questions
Is acacia invasive in the Bay Area?
Yes. Multiple acacia species are listed as invasive by the California Invasive Plant Council (Cal-IPC). Blackwood acacia, Bailey acacia, golden wattle, and green wattle all spread aggressively in Bay Area ecosystems, outcompeting native plants and forming dense monocultures on disturbed hillsides.
Do I need a permit to remove an acacia tree?
It depends on the city. Atherton and San Carlos exempt Bailey, green wattle and black acacia at any size. Belmont and Woodside still require a permit; Belmont issues it automatically and Woodside charges no fee. Oakland protects acacia at 9 inches DBH like any non-exempt species, and Berkeley regulates only coast live oak on private land. Most other cities apply their general size threshold. Check your city page before removing.
Are acacia trees a fire hazard?
Yes, acacias are among the highest fire-risk trees in the Bay Area. Volatile oils in foliage, retained dead branches, heavy litter accumulation, and dense growth patterns create extreme fuel loads. Fire departments in hillside areas strongly recommend removal of acacia within defensible space zones.
How do I prevent acacia from regrowing after removal?
Apply an appropriate herbicide to the fresh cut stump within 5 minutes of felling, this is the most critical step. Without stump treatment, most acacia species resprout vigorously from roots and stumps. Follow up by pulling seedlings from the soil seed bank for 5 to 10 years after removal.
What should I plant to replace acacia trees?
Native alternatives include coast live oak, toyon, California buckeye, and ceanothus for hillside sites. For faster results, consider native bunch grasses with scattered native shrubs. These provide erosion control and wildlife habitat with far less fire risk than the acacia they replace.
How long do acacia trees live?
Most Bay Area acacia species are short-lived, typically 20 to 50 years. Blackwood acacia may reach 50 years; Bailey acacia often declines after 20 to 30 years. The combination of fast growth and short lifespan means they become structurally hazardous relatively quickly.
Can acacia wood be used for anything?
Blackwood acacia produces attractive dark hardwood valued for furniture and turning. If you are removing a large blackwood, a local woodworker or sawyer may be willing to mill the trunk. Other acacia species have less valuable wood but can be chipped for mulch, use caution as chips may sprout.
Why do my neighbors' acacia seedlings keep appearing in my yard?
Acacia seeds are dispersed by birds, wind, and water, and can travel hundreds of feet from the parent tree. Seeds remain viable in soil for decades. The only long-term solution is removing the seed source, the parent tree. In the meantime, pull seedlings before they establish tap roots, ideally in their first year.
Where to Find Acacia in the Bay Area
City permit guides for areas where acacia is common:
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Written by Michael Schuck, ISA Certified Arborist WE-15750A · Updated May 2026
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Where acacia is protected: 56 Bay Area cities
32 of 56 jurisdictions regulate acacia on private property, each at its own size. The size is measured the way the city's code says (DBH or circumference, at the height shown). Rows come from the same rules the permit checker applies; the city page has the code section and the fee.
| City | Acacia | Rule it falls under |
|---|---|---|
| Atherton | Exempt | Eucalyptus, acacia (Bailey, green wattle, black), tree of heaven, mimosa, Monterey pine |
| Belmont | Protected at 14″ DBH at 54″ | as "Any other species (large diameter tree)" |
| Belvedere | Exempt | Undesirable species (blue gum eucalyptus, Monterey pine, Monterey cypress, poplar, green wattle and blackwood acacia; coast redwood is listed too but the City gives redwoods special consideration) |
| Berkeley | Not a listed species | Only the listed species are regulated on private property |
| Burlingame | Protected at 44″ circumference at 54″ | as "Any species" |
| Campbell | Not a listed species | Only the listed species are regulated on private property |
| Contra Costa County (unincorporated) | Not a listed species | Only the listed species are regulated on private property |
| Corte Madera | Exempt | Blue gum, sugar gum and manna gum eucalyptus, black acacia, green wattle acacia, Monterey pine, all junipers, Lombardy poplar |
| Cupertino | Not a listed species | Only the listed species are regulated on private property |
| Danville | Protected at 36″ DBH at 54″ | as "Any single-trunk tree 36" diameter or more (heritage)" |
| Dublin | Not a listed species | Only the listed species are regulated on private property |
| East Palo Alto | Protected at 8″ DBH at 54″ | as "Any species" |
| Fairfax | Protected at 12″ circumference at 54″ | as "Any species (every tree 12" circumference / 4" diameter)" |
| Foster City | No private-tree permit | Street and park trees only |
| Fremont | Protected at 18″ DBH at 54″ | as "Any species" |
| Hayward | Not a listed species | Only the listed species are regulated on private property |
| Hillsborough | Protected at 18″ DBH at 54″ | as "Any species" |
| Lafayette | Not a listed species | Only the listed species are regulated on private property |
| Larkspur | Protected at 50″ circumference at 24″ | as "Any species (heritage tree)" |
| Los Altos | Protected at 12″ DBH at 48″ | as "Any species" |
| Los Altos Hills | Not a listed species | Only the listed species are regulated on private property |
| Los Gatos | Protected at 12″ DBH at 54″ | as "Any species, developed residential lot"; developed residential |
| Marin County (unincorporated) | Not a listed species | Only the listed species are regulated on private property |
| Menlo Park | Protected at 47.1″ circumference at 54″ | as "Any other species" |
| Mill Valley | Not a listed species | Only the listed species are regulated on private property |
| Milpitas | Protected at 56″ circumference at 54″ | as "Any species, developed residential lot"; developed residential |
| Monte Sereno | Protected at 25″ circumference at 48″ | as "Any other species" |
| Moraga | Not a listed species | Only the listed species are regulated on private property |
| Mountain View | Protected at 48″ circumference at 54″ | as "Any other species" |
| Novato | Protected at 24″ DBH at 24″ | as "Any species, native or non-native (heritage tree)" |
| Oakland | Protected at 9″ DBH at 54″ | as "Any other species" |
| Orinda | Not a listed species | Only the listed species are regulated on private property |
| Pacifica | Exempt | Eucalyptus and Cal-IPC invasive species |
| Palo Alto | Protected at 15″ DBH at 54″ | as "Any other non-invasive, non-high-water-use species" |
| Piedmont | No private-tree permit | Street and park trees only |
| Pleasant Hill | Protected at 18″ DBH at 54″ | as "Non-native tree (except eucalyptus and palms)" |
| Pleasanton | Protected at 55″ circumference at 54″ | as "Any other species" |
| Portola Valley | Exempt | Any species not on the native significant-tree list |
| Redwood City | Protected at 38″ circumference | as "Any species" |
| Ross | Protected at 12.01″ DBH at 54″ | as "Any species, single trunk over 12" DBH (improved parcel)" |
| San Anselmo | Exempt | Acacia, eucalyptus, plum, privet, Monterey pine, liquidambar (nuisance trees) |
| San Bruno | Protected at 10″ DBH at 54″ | as "Any other species" |
| San Carlos | Exempt | Eucalyptus, Bailey/green/black acacia, tree of heaven, fruit trees, Monterey pine, palms |
| San Francisco | Protected at 12″ DBH at 54″ | as "Any species" |
| San Jose | Protected at 38″ circumference at 54″ | as "Any species" |
| San Mateo | Protected at 15″ DBH at 54″ | as "Any other species" |
| San Mateo County (unincorporated) | Exempt | Eucalyptus, pines, acacia, tanoak and bay laurel within 100 ft of a habitable structure or 30 ft of an evacuation road |
| San Rafael | No private-tree permit | Street and park trees only |
| Santa Clara | Protected at 38″ DBH at 54″ | as "Any other private tree" |
| Saratoga | Protected at 10″ DBH at 54″ | as "Any other species" |
| Sausalito | Exempt | Blue gum eucalyptus, Monterey pine, Monterey cypress, coast redwood, blackwood acacia, Bailey acacia, green wattle |
| South San Francisco | Protected at 75″ circumference at 54″ | as "Blue gum eucalyptus, black acacia, myoporum, sweetgum, glossy privet, Lombardy poplar" |
| Sunnyvale | Protected at 38″ circumference at 54″ | as "Any species" |
| Tiburon | Protected at 60″ circumference at 24″ | as "Any species (heritage size)" |
| Walnut Creek | Protected at 28″ circumference at 54″ | as "Any species" |
| Woodside | Protected at 36″ circumference at 48″ | as "Any other species" |
Street trees, city-designated heritage trees and trees required by a development approval are protected at any size in every city. Dead or hazardous trees still need the permit unless the city page says otherwise.