Local planting guide · California
zip 94401
San Mateo is in USDA hardiness zone 10a, with average winter lows of 30°F to 35°F. The local growing season runs roughly 12/29 through 12/26 (~365 days). This zip falls within the California growing region.
- USDA zone
- 10a 30°F to 35°F
- Last spring frost
- 12/29
- First fall frost
- 12/26
- Growing season
- 365 days
- Compatible crops
- 28
- Growing region
- California
Right now in San Mateo
Week 18 priorities
On the docket: transplant out after last frost · direct sow after last frost. See the full calendar →
Gardening in San Mateo
San Mateo's maritime climate creates one of the most unusual growing zones in California. Zone 10a temperatures bottom out around 30-35°F, but the timing of frost is what sets this area apart: a brief cold snap occurs around late December (frost risk through 12/26 to 12/29), while the rest of the year remains frost-free. This effectively eliminates the traditional "spring" and "fall" frost boundaries, yielding a 365-day growing season.
The coastal influence that brings reliable fog also keeps summers far cooler than inland zone 10a regions. This is both advantage and challenge. Heat-loving crops like fig, Asian persimmon, pomegranate, and goji berry thrive in the mild, extended season. Tomatoes and peppers also grow exceptionally well, provided varieties are chosen for the cooler coastal summers rather than extreme heat. The fog moderates temperature swings, reducing sunburn risk on tender crops and eliminating the blistering heat that compromises fruit set in inland California.
Regional context · California
What the California brings to San Mateo
From cool foggy coast to hot Central Valley to mountain to desert. Mediterranean climate dominates: wet winters, dry summers. The most productive agricultural state in the country, with reach into citrus and olives that exceed the rest of the country.
Common challenges
Issues that most often defeat home gardeners in zone 10a, drawn from the broader USDA zone profile.
- ▸ No chilling for traditional temperate fruit
- ▸ Hurricane exposure
- ▸ Heat-tolerant cultivars only
What defeats new gardeners in San Mateo
Coastal fog brings fungal disease pressure that inland zone 10a gardeners rarely face. Powdery mildew and leaf spot diseases escalate in summer when morning fog combines with cool nights. Tomatoes and peppers are most vulnerable; poorly-spaced plants or overhead watering exacerbate the problem.
The December frost window, while brief, catches many gardeners off-guard. A light freeze around 12/26 to 12/29 can kill back tender evergreen perennials and new growth on figs and citrus. The other challenge specific to San Mateo is the cool summer itself: crops demanding consistent heat and long daylight (some Southern varieties of sweet pepper, melon, okra) may underperform or set fruit late despite the year-round growing window.
Crops that grow in San Mateo
28 crops from our catalog match zone 10a, grouped by type.
Tree fruit
12 crops
zone 10a Fig
Ficus carica
zones 7a–10b
zone 10a Asian Persimmon
Diospyros kaki
zones 7a–10a
zone 10a Pomegranate
Punica granatum
zones 7b–10a
zone 10a Lemon
Citrus limon
zones 9a–11b
zone 10a Orange
Citrus sinensis
zones 9a–11b
zone 10a Lime
Citrus aurantiifolia
zones 9b–11b
zone 10a Grapefruit
Citrus paradisi
zones 9a–11b
zone 10a Avocado
Persea americana
zones 9b–11b
Berries
3 crops
Nuts
1 crop
Vegetables
10 crops
zone 10a Tomato
Solanum lycopersicum
zones 3a–10b
zone 10a Sweet Pepper
Capsicum annuum
zones 4a–10b
zone 10a Hot Pepper
Capsicum species
zones 4a–10b
zone 10a Eggplant
Solanum melongena
zones 5a–10b
zone 10a Cucumber
Cucumis sativus
zones 3b–10a
zone 10a Summer Squash
Cucurbita pepo
zones 3b–10a
zone 10a Melon
Cucumis melo
zones 5a–10a
zone 10a Watermelon
Citrullus lanatus
zones 5b–10a
Herbs
2 crops
Plan the year
Planting calendar for San Mateo
Year-view of seed starting, transplanting, planting, pruning, fertilizing, harvest, and pest-watch windows tuned to San Mateo's local frost dates.
Week ? · loading
This week in San Mateo, CA (zone 10a)
Quiet week in San Mateo, CA (zone 10a). this week is a good time to step back and plan ahead.
Nothing critical on the calendar this week.
147 bars · 28 crops
Calendar logic combines NOAA frost normals with crop-specific timing data. Local microclimate and weather always overrules the calendar; use this as a starting point.
Top pests for zone 10a
Ranked by how many crops in your zone they affect. Click through for IPM controls and signs to watch for.
Pseudococcidae spp.
Soft white waxy insects that cluster at leaf joints, fruit stems, and root crowns. Honeydew secretion supports sooty mold; root mealybugs cause decline that mimics drought.
Meloidogyne species
Microscopic soil-dwelling worm that forms galls on roots, reducing vigor and yield.
Multiple species (Aphididae)
Small soft-bodied sap-sucking insects that reproduce explosively in spring. Excrete honeydew that supports sooty mold and attracts ants. Transmit viral diseases.
Multiple species (Aleyrodidae)
Tiny white moth-like flying insects that feed on plant sap and excrete honeydew. Transmit numerous viral diseases including tomato yellow leaf curl virus.
Coccoidea spp.
Sap-sucking insects that attach to bark, leaves, and fruit, secreting honeydew that fuels sooty mold. Heavy infestations weaken trees and cause leaf yellowing.
Tetranychus urticae
Tiny mite that feeds on leaf undersides, causing stippling and webbing during hot dry weather.
Ceratitis capitata
Quarantine pest in many regions. Adult females puncture ripening fruit to lay eggs; larvae tunnel through the flesh, causing premature drop and rot.
Multiple species (Chrysomelidae)
Tiny black or bronze jumping beetles that put hundreds of small holes in seedling leaves. Most damaging on direct-seeded brassicas and young eggplant.
Top diseases for zone 10a
Ranked by how many crops in your zone they affect. Click through for symptoms, controls, and resistant varieties.
Capnodium spp.
Black fungal coating that grows on honeydew secreted by aphids, scale, mealybugs, and whiteflies. Doesn't infect plant tissue directly but blocks photosynthesis and disfigures fruit.
Cucumber mosaic virus, Tobacco mosaic virus, and others
Family of plant viruses producing mottled yellow-and-green leaf patterns. Vectored primarily by aphids; some are seed-transmitted or spread by handling tools and tobacco products.
Calcium deficiency physiological disorder
Not a true disease but a calcium-uptake disorder caused by inconsistent soil moisture during fruit development. The dominant cause of damaged first-fruit on home tomato plantings.
Sclerotium rolfsii
Soil-borne fungal disease most damaging in warm humid Southern conditions. White mycelial fans and small mustard-seed-sized sclerotia at the soil line are diagnostic.
Pythium and Rhizoctonia species
Soil-borne complex of water molds and fungi that kill seedlings before or shortly after emergence. The single most common cause of seed-starting failures.
Fusarium oxysporum
Soil-borne fungal disease that plugs vascular tissue and kills affected plants. Persists in soil for many years; impossible to eliminate once established.
Colletotrichum gloeosporioides
Most damaging mango disease worldwide. Fungal spores infect blossoms and developing fruit during humid weather, producing black sunken lesions that expand on ripening fruit.
Multiple species (Erysiphales)
Surface-feeding fungal disease producing white powdery growth on leaves and stems. Reduces yield by stealing photosynthate and accelerating senescence.
Companion planting suggestions
Beneficial pairings drawn from companion data, filtered to crops that grow in zone 10a.
- Fig + Rosemary
Rosemary tolerates the dry sites figs prefer and provides aromatic pest deterrence.
- Tomato + Basil
The classic Italian pairing. Basil's volatile oils are reported to repel hornworms and whiteflies, and the two crops share the same warm-season schedule and water needs. Plant basil between tomato cages.
- Sweet Pepper + Basil
Same warm-season culture, same watering schedule. Basil reportedly improves pepper flavor and repels aphids and thrips that are pepper's primary pests.
- Hot Pepper + Basil
Compatible heat-loving culture, similar water needs. Basil interplanted between hot pepper plants supports beneficial insects and reduces aphid pressure.
- Okra + Hot Pepper
Both heat-loving warm-season crops with similar water and fertility needs. Hot pepper at okra's base benefits from the slight afternoon shade in extreme summer heat.
Soil types reference
Soil texture and pH decide what grows easily on your specific lot. Find the closest match below for crop recommendations and amendment guidance.
Practical tips for San Mateo
Plant tomatoes in two windows to sidestep both fog-disease pressure and frost risk: early spring (February-March) for a May-June harvest before fog intensifies, and midsummer (July-August) for a fall harvest as humidity drops. Fog-tolerant varieties like Brandywine or Early Girl outperform humidity-sensitive types.
Apply light frost cloth or mulch protection to tender evergreen crops in late December when the brief cold snap nears. A simple frost cover, pulled at dawn, saves figs, persimmons, and citrus from die-back without requiring a greenhouse.
Leverage the year-round season for succession planting. Plant cool-season crops (brassicas, lettuce, root crops) in fall through early spring, then swap to warm-season crops for summer. The 365-day window means two or even three plantings of faster-maturing crops per calendar year.
Frequently asked questions
- What can I reliably grow year-round in San Mateo?
Figs, Asian persimmons, pomegranates, and citrus are the most reliable warm-season perennials. Cool-season crops like lettuce, kale, broccoli, and root vegetables thrive fall through spring. Tomatoes and peppers also work well in both spring and fall plantings; summer fog limits their window. The only significant frost risk (12/26-12/29) briefly threatens tender new growth, so plan plantings to avoid coinciding with this window.
- When should I plant tomatoes to avoid frost and disease?
Plant tomatoes in early spring (February-March) or midsummer (July-August). Spring plantings yield fruit before fog intensifies in June. Midsummer plantings mature in fall as humidity drops and fog retreats. Avoid late spring and early summer sowings, which clash with the season's highest fog and disease pressure. Choose fog-tolerant varieties like Brandywine, Early Girl, or Stupice for coastal conditions.
- Do I need frost protection in San Mateo?
Brief frost protection is needed only around late December (12/26-12/29), when a light freeze poses mild risk to tender perennials and new growth on evergreens. A simple frost cloth applied overnight, then removed at dawn, suffices for figs, citrus, persimmons, and new plantings. Most of the year requires no frost concern; the growing season is effectively 365 days.
- Why do Asian persimmons thrive in San Mateo?
Asian persimmons ripen fully in San Mateo's long frost-free season and cool summers. They prefer the extended autumn to accumulate sugars before the brief December frost, and the marine climate reduces pest pressure (especially spider mites that plague inland varieties). The moderate heat sidesteps the sunburn and quality loss that occurs in hotter inland zones.
- Can I grow pomegranate in San Mateo?
Yes. Pomegranate grows reliably here with the long season, though fruit colors may be less vivid than in hotter inland zones due to cooler summers. Grenadine or Mollar varieties are better choices than heat-demanding types. Fruit matures by fall before the brief December frost, and the plant's cold-hardiness to 10-15°F ensures survival even during the cold snap.
- What's the biggest weather risk for gardeners in San Mateo?
Summer fog brings fungal disease pressure more severe than most other zone 10a regions. Powdery mildew, leaf spot, and damping-off diseases escalate when cool mornings and high humidity persist. The secondary risk is underestimating the late December frost (12/26-12/29), which can kill back unprotected tender growth despite the overall mild climate.
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Frost data: NOAA Climate Normals 1991-2020, station USW00023234. Local microclimates can shift these dates by a week or more.
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