At a glance
- Region ID: NORCAL-COAST
- Anchor cities: San Francisco, Santa Rosa
- USDA Hardiness Zones: 9b–10a
- Climate: Mediterranean coastal — cool foggy summers, mild wet winters, minimal frost, persistent marine influence, excellent conditions for Mediterranean and temperate-climate plants
- Catalog size: 83 plants
- Climate factors: Fire risk in WUI areas, year-round growing season, summer fog on the coast, Diablo wind events in fall
Pruning & maintenance calendar
January – February
Major structural pruning window. Rose pruning. Wet season — work between rain events. Best time for major cuts on most deciduous species before bud break.
March – April
California lilac and manzanita bloom. Post-bloom pruning only — never prune before or during bloom. Wildflower season on coastal hillsides.
May – June
Transition to dry season. Fog belt areas remain cool; inland valleys warm rapidly. Fire clearance prep in WUI zones — defensible space brush clearing. Last chance to shape rosemary before summer.
July – September
Dry season. Fog keeps coast cool. NO irrigation on native plantings — California lilac and manzanita die from Phytophthora if summer-watered. Lily of the Nile bloom season. Deadhead spent agapanthus stalks.
October – November
Fire risk peak — Diablo winds bring hot dry offshore air. First rains arrive. Fall planting window opens — the best planting season for natives. Transplanting and new installations timed to first consistent rain.
December
Wet season. Minimal activity. Storm damage assessment. Winter pruning begins on deciduous species late in the month.
Regional pest & pathogen pressure
- Phytophthora root rot — kills summer-irrigated native plants. Tell: sudden wilting and branch dieback on California lilac and manzanita that have been receiving summer water. Prevention is cultural: no summer irrigation on native plantings.
- Sudden oak death (Phytophthora ramorum) — devastating to tan oak and coast live oak in coastal forests. Quarantine areas exist in multiple counties. Tell: bleeding cankers on trunk, rapid crown dieback. Report suspected cases to your county agricultural commissioner.
- Shot hole borer — increasing pressure. Invasive ambrosia beetle boring into a wide range of landscape trees. Tell: small entry holes with staining or sugar exudate on bark.
- Olive knot on olive trees — bacterial gall (Pseudomonas savastanoi) spread on pruning tools. Tell: rough woody galls at nodes and wounds on olive branches. Sterilize pruning tools between cuts.
- Snails and slugs — year-round pressure in foggy coastal conditions. Heavy on tender perennials and groundcovers.
- Eucalyptus tortoise beetle — on eucalyptus plantings. Skeletonizes leaves. Cosmetic primarily but heavy infestations reduce vigor.
- Fire risk in WUI interface areas — not a pest, but the dominant management consideration in many Northern California coastal landscapes. Defensible space requirements dictate plant selection and maintenance schedules.
- Phormium yellow leaf virus — on New Zealand flax. Tell: yellow streaking and mottling on leaves. No cure; remove infected plants to prevent spread.
Core staples (commonness 1)
Currently: 6 of 83 plants profiled. Remaining plants tracked in the catalog data.
California Lilac
Core staple · NativePruning — immediately after spring bloom
Spectacular blue spring bloom across dozens of species and cultivars. NO summer irrigation — Phytophthora root rot kills summer-watered plants reliably. Nitrogen-fixing (enriches soil without fertilizer). Relatively short-lived (10–15 years), but fast-growing and self-seeding in favorable sites. Prune only after bloom; never cut into old wood. Many species available from prostrate groundcovers to large shrubs.
Common pathogens
Disease Phytophthora root rot
The defining killer of California lilac in cultivation. Caused by summer irrigation. Plants wilt suddenly and die. Prevention is entirely cultural: do not irrigate after establishment.
Manzanita
Core staple · NativePruning — light shaping after bloom; structural pruning in winter
Sculptural red-brown exfoliating bark is the signature ornamental feature. NO summer irrigation — same Phytophthora vulnerability as California lilac. Dr. Hurd cultivar trains as a stunning small multi-trunk tree (to 15 ft). Prostrate species (A. uva-ursi, 'Emerald Carpet') work as groundcover. Urn-shaped white-pink flowers in winter/early spring attract native pollinators.
Common pathogens
Disease Phytophthora root rot
Same mechanism as California lilac — summer irrigation is fatal. Established plants in native soil need zero supplemental water.
Rosemary
Core staplePruning — spring through early summer; light shaping only
Northern California's Mediterranean climate is ideal for rosemary — it thrives with minimal care. Never cut into old bare wood — rosemary does not regenerate from leafless stems. Prune only into green growth. Prostrate forms ('Huntington Carpet', 'Irene') excellent for groundcover and erosion control on slopes. Upright forms ('Tuscan Blue', 'Arp') for hedging and screening.
New Zealand Flax
Core staplePruning — remove dead or damaged leaves at base year-round
Dramatic architectural sword-like leaves — the signature accent plant in Northern California coastal landscapes. Bronze, red, and variegated cultivars widely available. Salt-tolerant and wind-tolerant — performs well in exposed coastal sites. Mass plantings create bold structural statements. Remove spent flower stalks after bloom.
Common pathogens
Disease Phormium yellow leaf virus
Yellow streaking and mottling on leaves. No cure. Remove and destroy infected plants to prevent spread to adjacent specimens.
Lily of the Nile
Core staplePruning — deadhead spent flower stalks; remove tattered foliage in late winter
Blue globe flowers on tall stalks July through September — mass plantings are a California signature. Drought-tolerant once established. Evergreen in the coastal zone; may go semi-dormant inland. Divide congested clumps every 4–5 years to maintain bloom vigor. 'Storm Cloud' (deep blue) and 'Peter Pan' (dwarf) are the most-specified cultivars in the region.
Fruitless Olive
Core staplePruning — late winter to early spring; thin interior for air circulation
Mediterranean texture and silver-green foliage — iconic in Northern California landscapes. Swan Hill and Wilsonii are the fruitless cultivars specified to avoid the mess of fruiting olives. Some municipalities restrict olive planting (pollen/fruit ordinances) — check local codes before specifying. Extremely drought-tolerant and long-lived once established.
Common pathogens
Disease Olive knot
Bacterial gall (Pseudomonas savastanoi) forming rough woody galls at nodes and pruning wounds. Spread on contaminated pruning tools — sterilize between cuts. Prune in dry weather only.
Inside the app
Skip the spreadsheet. Verdant Meridian seeds your library with the regional palette on day one.
Pick your region at onboarding — the app loads commonness-1 and commonness-2 plants into your element library.
Try Free — 30 DaysHow this list was built
Compiled from regional wholesale grower availability lists — not retail garden references. No chemical, fungicide, or product recommendations appear anywhere in this database. Diagnostic and cultural information only.
FAQ
What hardiness zone is San Francisco?
San Francisco is USDA Zone 10a–10b coastal. Santa Rosa is 9b. Fog moderation keeps temperatures mild year-round — frost is rare on the immediate coast, and summer highs are kept in check by persistent marine influence.
Can I water California lilac in summer?
No. Summer irrigation kills California lilac (Ceanothus) via Phytophthora root rot. California natives are adapted to summer-dry conditions — the Mediterranean climate means dry summers and wet winters.
What native plants work in San Francisco?
California lilac (Ceanothus), manzanita (Arctostaphylos), coast live oak, California fuchsia, and buckwheat. All are summer-dry adapted and thrive without supplemental irrigation once established.
What is sudden oak death?
Caused by Phytophthora ramorum — devastating to tan oak and coast live oak in coastal forests. Quarantine areas exist in multiple Northern California counties. Report suspected cases to your county agricultural commissioner.
When is the best time to plant in Northern California?
Fall — October through November — after the first rains. Roots establish through the wet winter months, and plants are ready for summer drought by spring. This is especially critical for native plantings that will not receive summer irrigation.
Cite this page
Verdant Meridian, “Northern California Coastal Plant Palette,”
verdantmeridian.app/regions/norcal-coast, updated May 2026. CC-BY-4.0. Raw data: /data/plants.json.Published under CC-BY-4.0. Free to use, redistribute, build on — attribution required.
