San Francisco Native Plants Rescue

Key Takeaways

San Francisco native plant rescue requires matching species to microclimate zones — upper slopes need supplemental drip irrigation, while lower slopes can thrive on winter rainfall alone once established.

Priority rescue species include Ceanothus ‘Dark Star’, flannel bush (Fremontodendron californicum), California fuchsia (Epilobium canum), Pacific Coast iris, and purple needle grass (Stipa pulchra) — all adapted to SF’s shallow, fast-draining soils and summer fog.
Core tools needed: drip irrigation emitters (0.5–1 GPH), a soil pH meter (target 6.0–7.0), native-compatible mycorrhizal inoculant, and bypass pruners for winter cutback maintenance.

The single biggest failure point is overwatering established natives in summer — most SF natives evolved for complete summer drought and will root-rot if treated like conventional landscape plants.

Rescuing a neglected piece of public or private land in San Francisco using native plants is one of the most ecologically rewarding — and technically demanding — projects a gardener or landscape professional can undertake. The city’s unique topography creates a patchwork of coastal scrub, northern coastal scrub, and mixed evergreen forest microclimates, often compressed into a single city block. A south-facing slope on Corona Heights behaves nothing like the foggy, wind-battered western edge of McLaren Park. Getting this right demands site-specific plant selection, a clear understanding of SF’s soil geology, and a seasonal maintenance calendar tuned to the Mediterranean rhythm of wet winters and bone-dry summers.

This guide draws on the ecology of SF’s native plant communities, hands-on restoration horticulture, and real-world data to give you everything you need — from initial site assessment through long-term community stewardship.

Understanding San Francisco’s Unique Horticultural Context

San Francisco is not simply “California.” It is a peninsula of extreme microclimates compressed into 49 square miles. The city sits at the interface of the Pacific Ocean, San Francisco Bay, and the Coast Ranges, producing conditions that have no equivalent elsewhere in the state.

Key abiotic factors shaping native plant selection:

Summer fog: Advection fog from the Pacific delivers measurable foliar moisture in July and August, creating an effective “phantom rainfall” of 0.5–1.5 inches monthly in western neighborhoods. This is why Ceanothus and flannel bush — which would die from summer water on the Peninsula — can sometimes tolerate slightly more moisture on SF’s west side.
Soils: Most of SF sits on franciscan chert, serpentinite, or graywacke sandstone. These parent materials produce shallow, low-nutrient, often alkaline-to-slightly-acidic soils that are exactly what native plants need — and exactly what most imported landscape plants cannot tolerate without amendment.

Wind exposure: The Sunset and Richmond districts average sustained winds of 15–25 mph on summer afternoons. This dramatically increases evapotranspiration on exposed plants and favors low-growing, flexible-stemmed species over tall, rigid exotics.
Hardiness: USDA Zone 10a–10b throughout most of the city means frost is rarely the limiting factor. The real stress is summer drought combined with wind desiccation.

Understanding these parameters means your plant palette is not determined by a catalog — it is determined by reading the land.

Phase 1 — Site Assessment Before You Plant a Single Seedling

Skipping thorough site assessment is the reason most SF native plant rescues fail within three years. Here is a systematic protocol:

Soil Analysis

Collect soil samples from at least three points across your site at 4-inch and 10-inch depths. Test for:

pH (target 6.0–7.0 for most SF natives; serpentine-derived soils may push 7.5–8.0)

Organic matter percentage (SF urban soils often sit below 1% OM — do not add compost unless below 0.5%, and even then, use no more than 10% by volume in the planting hole)
Drainage rate (dig a 12-inch hole, fill with water, let drain, refill — measure how many inches drain per hour; natives need ≥1 inch/hour)
Compaction (penetrometer reading >300 psi indicates a problem; use broadfork or hand-rip before planting)

Slope and Aspect Mapping

Mark north-facing and south-facing zones separately on a site sketch. North-facing slopes retain moisture longer and support shade-tolerant species like tufted hair grass (Deschampsia cespitosa) and sword fern (Polystichum munitum). South-facing slopes dry out aggressively and favor drought-hardened species like Arctostaphylos cultivars and Cleveland sage (Salvia clevelandii).

Weed Inventory

Before removing anything, identify every weed species present. This matters because removal strategy differs:

Cape ivy (Delairea odorata): Requires repeated cutting plus root removal; do not compost.

Himalayan blackberry (Rubus armeniacus): Cut at soil level, return in 3 weeks, cut again — requires 2–3 seasons of follow-up.
French broom (Genista monspessulana): Pull when soil is wet; seed bank persists 10+ years, requiring vigilance.
Kikuyu grass (Cenchrus clandestinus): One of the most problematic in SF — requires solarization or repeated smothering with cardboard/woodchip mulch; herbicide-free removal is labor-intensive but essential in ecologically sensitive zones.

Phase 2 — The Plant Palette: Species-by-Species Technical Breakdown

Not all “California natives” are San Francisco natives. Many species sold at Bay Area nurseries originate from Southern California, the Central Valley, or the Sierra Nevada and perform poorly in SF’s summer fog-and-cool-temperatures regime. The following species are specifically vetted for SF conditions.

Upper Slope Species (Requires Supplemental Irrigation in Years 1–2)

Coast Live Oak (Quercus agrifolia)
The structural anchor of any SF native planting on upper slopes. Grows 20–70 feet depending on exposure. Plant from a 1-gallon container — avoid 5-gallon trees, which are often pot-bound and develop circling roots that girdle the trunk within a decade. Mulch 3–4 inches deep in a 3-foot radius, keeping mulch away from the root crown. Water deeply (slow trickle for 2–3 hours) every 3–4 weeks in summer during the first two years, then cease all supplemental summer water.

Catalina Ironwood (Lyonothamnus floribundus ssp. asplenifolius)
Despite the name, this is an outstanding performer in SF and other coastal California urban environments. Its ferny leaves and peeling reddish bark provide multi-season interest. It is moderately fast-growing (1–2 feet per year) and once established tolerates both drought and occasional summer fog moisture. Excellent as a windbreak species on upper slopes.

California Fescue (Festuca californica)
The premier ornamental bunchgrass for SF’s shadier upper slopes. Unlike blue fescue (F. glauca), which originates in Europe and struggles in SF’s fog, F. californica evolved in exactly these coastal conditions. Clumps reach 2–3 feet with arching blue-green blades. Divide every 4–5 years when center of clump dies back. Do not cut back hard — unlike grasses from summer-rain climates, it does not respond well to severe cutting.

Blue-Eyed Grass (Sisyrinchium bellum)
Actually a member of the iris family, not a true grass. Forms tight 6–12-inch clumps with violet-blue spring flowers. Self-seeds readily, which is desirable — it fills in gaps between larger plants. Tolerates both sun and partial shade, making it uniquely versatile on transitional slope positions.

Pacific Coast Iris (PCH hybrids and Iris douglasiana)
Among the most garden-worthy of all SF natives. The naturally occurring Iris douglasiana is found in SF’s own coastal scrub remnants. PCH hybrid selections offer expanded color range while retaining coastal adaptability. Plant in well-drained soil; rhizomes must never sit in standing water. Divide every 3–4 years after bloom — in SF, this means mid-June.

Purple Needle Grass (Nassella pulchra, formerly Stipa pulchra)
California’s state grass and the dominant bunchgrass of the pre-settlement Bay Area grasslands. Plant density: 18–24 inches on center for a meadow-style effect. Its seed heads turn golden-bronze in summer, providing visual interest precisely when most other plants look dormant. Critically important for ground-nesting native bee habitat.

Checkerbloom (Sidalcea malviflora)
Produces rose-pink flowers on 18–24-inch stems from April through July. Often underused in SF native plant rescues — it is extremely effective at suppressing weeds through dense basal rosette coverage. Cut flower stalks after bloom to encourage reblooming; divide clumps every 3 years.

Tufted Hair Grass (Deschampsia cespitosa)
The go-to grass for SF’s shadiest, moister spots — north-facing slopes, areas under oak canopy, or zones near downspouts. Produces airy, shimmering seed heads that catch low fog-light beautifully. Unlike many grasses, it tolerates both summer moisture and some drought once its root system is established at depth.

Bush Anemone (Carpenteria californica)
Technically a Central Valley foothills native, but performs exceptionally well in SF’s cooler, foggy conditions. Produces large white flowers in May–June. Prune lightly after bloom — remove dead wood and crossing branches. Avoid hard rejuvenation cuts, which can cause dieback in coastal conditions.

Lower Slope Species (Winter Rainfall Only After Establishment)

Manzanita (Arctostaphylos spp.)
The genus Arctostaphylos contains over 60 California species, with the City of San Francisco being home to two rare endemic species: A. franciscana (Franciscan manzanita, critically endangered) and A. imbricata (Rincon Hill manzanita, presumed extinct in the wild). For restoration work, use only verified local-ecotype plants from reputable native nurseries like Yerba Buena Nursery or East Bay Nursery. For ornamental lower-slope planting, compact cultivars like A. ‘Howard McMinn’ or A. uva-ursi ‘Point Reyes’ are appropriate. Critical rule: never water in summer after establishment, even during a heat wave. Summer water on Arctostaphylos causes phytophthora root rot within weeks.

Ceanothus ‘Dark Star’
This cultivar is a hybrid of C. impressus × C. papillosus that has proven itself across decades of SF use. It produces dense, cobalt-blue flower clusters in March–April, growing 5–6 feet tall and wide. Plant it where it will never need to be cut back — Ceanothus does not regenerate from old wood. Position it at least 4 feet from paths and 6 feet from structures. Established plants are strictly no-summer-water.

Flannel Bush (Fremontodendron californicum)
Spectacular — golden-yellow 2-inch flowers cover the plant from April through June. It requires perfect drainage and zero summer water. Even accidental irrigation from a nearby sprinkler head will kill it. Plant on berms or raised mounds if your site has any drainage uncertainty. Leaves and stems have fine hairs that cause skin and eye irritation — wear gloves and eye protection when handling.

Cleveland Sage (Salvia clevelandii)
Native to Southern California’s coastal chaparral, S. clevelandii has naturalized exceptionally well in SF’s fog belt. Its intensely fragrant foliage is highly deer-resistant. Grows 3–5 feet tall; prune by one-third in late fall after seeds have dispersed (leaving seed heads through September benefits goldfinches and white-crowned sparrows). Do not shear flat — always cut back to a lateral branch junction.

California Fuchsia (Epilobium canum, formerly Zauschneria californica)
Blooms brilliant orange-red from August through October — exactly when most other SF natives look tired. This makes it strategically critical for late-season pollinator support, particularly for the Allen’s hummingbird. Spreads by underground rhizomes; contain it with a root barrier if space is limited. Cut to within 4 inches of the ground in February before new growth begins.

California Poppy (Eschscholzia californica)
The state flower is technically an annual-perennial depending on conditions. In SF’s mild climate, it behaves as a short-lived perennial, self-seeding prolifically. Scatter seed directly on bare soil in October–November; do not transplant. It resents root disturbance and will fail if started in pots and transplanted. Allow seed heads to shatter naturally — deadheading prevents naturalization.

Phase 3 — Irrigation Design for Two-Zone Native Plantings

The most critical technical decision in an SF native plant rescue is the irrigation split between the upper establishment zone and the lower no-summer-water zone. Getting this wrong kills plants on both sides of the line.

Upper Slope Drip System Design

Use pressure-compensating emitters at 0.5 GPH (gallons per hour) — never use 1 GPH emitters on SF’s shallow soils, as water penetrates too fast and creates a wet surface zone rather than deep root penetration.

Target irrigation depth: 18–24 inches
Method to check: After irrigating, insert a soil probe or rebar — it should slide easily to 18 inches through wet soil. If it stops at 6 inches, you are underwatering even if the surface looks wet.

Establishment irrigation schedule (Years 1–2):

Month	Frequency	Duration per session	Notes
Nov–Mar	0 (rely on rain)	—	Suspend system if >0.5″ rain/week
April	Every 14 days	45 min	Monitor soil moisture with probe
May	Every 10 days	45 min	Increase if winds are strong
June	Every 7 days	60 min	Critical establishment period
July	Every 7 days	60 min	Highest stress period
August	Every 10 days	60 min	Fog events may allow reduction
September	Every 14 days	45 min	Begin tapering
October	Every 21 days	30 min	Pre-rain season wind-down

Post-establishment (Year 3+): Reduce to every 21–28 days in June–September, or eliminate entirely for the most drought-tolerant species (Arctostaphylos, Ceanothus, flannel bush).

Lower Slope: No Irrigation After Year 1

For the lower slope, irrigation during establishment (first winter and spring) is critical, then must be stopped. Use temporary drip on a separate valve — clearly labeled — so it can be turned off permanently in the second summer. Leaving summer water running on Ceanothus or flannel bush because “they looked stressed” is the single most common cause of plant death in SF native restorations.

The SF Native Plant Rescue Troubleshooting Matrix

This is the data resource that most generic guides omit entirely. Use this table to diagnose problems in the field.