San Mateo County, CA — Planting Guide
Top priorities for San Mateo County, California gardeners in May
May is a pivotal month for San Mateo County, California gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Collect basil, cucumber, and green beans at their peak
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
Looking ahead to June
- First harvests: peppers, tomatoes, and alpine strawberries
San Mateo County is in USDA Zone 10a. The average last spring frost is January 18 and the first fall frost is December 12, giving you a growing season of approximately 329 days.
At an elevation of 277 ft, San Mateo County receives approximately 16.9 in of rainfall annually. Summer highs average 81°F with winter lows around 65°F. The predominant soil type is Loam.
Based on 13 years of NOAA climate station data, the last frost date here varies by 79 days year to year — ranging from January 5 in warm years to March 24 in cold years. The growing season is trending longer by about 25.71 days per decade. San Mateo County scores 44/100 (Moderate) on the Microclimate Index.
🌡️ Zone
10a (°F to °F min)
❄️ Last Frost
January 18
🍂 First Frost
December 12
📅 Growing Season
329 days
⛰️ Elevation
277 ft
🌧️ Annual Rainfall
16.9 in
Monthly Watering Calendar
When you'll need to water your garden — based on average monthly rainfall vs. the ~1 inch/week most gardens need.
View detailed monthly data
| Month | Avg Rainfall | Rainy Days | Extra Water Needed | Watering Effort |
|---|---|---|---|---|
| Jan | 3.9 in | 8 days | 0.4 in | Low |
| Feb | 3.4 in | 9 days | 0.9 in | Moderate |
| Mar | 2.7 in | 8 days | 1.6 in | High |
| Apr | 1.2 in | 5 days | 3.1 in | Critical |
| May | 0.4 in | 1 days | 3.9 in | Critical |
| Jun | 0.1 in | 1 days | 4.2 in | Critical |
| Jul | 0 in | 0 days | 4.3 in | Critical |
| Aug | 0 in | 0 days | 4.3 in | Critical |
| Sep | 0.2 in | 1 days | 4.1 in | Critical |
| Oct | 0.7 in | 3 days | 3.6 in | Critical |
| Nov | 1.4 in | 6 days | 2.9 in | High |
| Dec | 2.9 in | 9 days | 1.4 in | Moderate |
Annual total: 16.9 in. Water needs vary by crop — tomatoes need ~1.2"/week while herbs like rosemary need only 0.3"/week. Check individual plant pages for crop-specific water budgets that factor in your county's rainfall and soil drainage.
San Mateo County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.2
Drainage
Well Drained
Frost Risk Probability
Based on 13 years of NOAA weather station data from 3 stations
Beginners: Plant frost-sensitive crops (tomatoes, peppers, squash) after the "Safe" date on the left. Harvest or cover them before the "Protect by" date on the right. Hardy crops (lettuce, peas, kale) can go in the yellow transition zones.
How to read this table: "Conservative" means you're safe from frost 9 out of 10 years — best for beginners and frost-sensitive crops. "Average year" is the typical date. "Aggressive" means only 1 in 10 years is that warm — experienced gardeners with frost protection can try these dates.
| Planting Strategy | Last Spring Frost | First Fall Frost | Frost-Free Days |
|---|---|---|---|
| Conservative (safest) | Mar 24 | Dec 24 | 275 days |
| Cautious | Feb 17 | Dec 19 | 305 days |
| Average year | Jan 18 | Dec 12 | 328 days |
| Optimistic | Jan 14 | Dec 5 | 325 days |
| Aggressive (risky) | Jan 5 | Nov 22 | 321 days |
Not very — frost dates can vary by ±79 days year-to-year. Use the "Conservative" row in the table below, and keep row covers handy for surprise late frosts.
Yes — growing seasons are getting longer here (about 25.7 days per decade). Spring is arriving earlier than it used to. Good news for gardeners.
Gardening Difficulty Score
San Mateo County presents some gardening challenges. Choose adapted varieties and plan around frost dates.
Local Gardening Help in San Mateo County
Free expert help is closer than you think. Your county's cooperative extension office connects you with trained gardeners, soil testing labs, and local programs — all specific to San Mateo County's climate and soil.
County Extension Office
San Mateo County University of California Cooperative Extension Extension Office
Phone: 530-750-1200
Visit Extension Office Website →
Extension offices are run by land-grant universities and funded by the USDA. Their advice is free, research-based, and tailored to your county's specific conditions.
Master Gardener Program
Free gardening help from trained volunteers
Master Gardeners are community volunteers who complete 40–60 hours of university horticultural training. They answer gardening questions, diagnose plant problems, and offer workshops — all free.
Many extension offices run a Master Gardener hotline where you can call or email with photos of plant problems for free diagnosis.
Soil Testing
Available through your extension office
Before amending your soil, get it tested. Your extension office offers soil testing (typically $10–$25) that tells you exact pH, nutrient levels, and amendment recommendations specific to what you want to grow.
Services Available in San Mateo County
Finding local nurseries & garden centers in San Mateo County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to San Mateo County's soil and climate that big-box stores can't. Plants from local growers are typically hardier because they're already acclimated to your zone.
How to Find Them
Search for "nurseries near San Mateo County CA" or "garden center San Mateo County" on Google Maps. Also check with your extension office — they often maintain lists of reputable local nurseries and plant sales.
Community gardens & gardening groups
Community gardens are a great way to learn from experienced gardeners in your area, especially if you're limited on space. Search "community garden San Mateo County CA" or check your extension office and local parks department. Facebook groups like "San Mateo County Gardeners" or "California Gardening" are also excellent for local advice and plant swaps.
What to Plant After Your Harvest
After your first crops finish, use the remaining frost-free days to grow a second round.
Show 6 more succession options
Sunlight & Day Length
Monthly daylight hours and peak sun — critical for onion varieties, photoperiod-sensitive plants, and solar garden planning.
Longest Day
14.6 hours
Summer solstice daylight
Shortest Day
9.4 hours
Winter solstice daylight
Peak Sun Hours
12.9 hr/day peak (summer)
Peak sun hours (green dashed line below) account for cloud cover — this is the usable direct sunlight your garden actually receives. Most vegetables need 6+ peak sun hours.
Onion tip: Your long summer days (14+ hours) support long-day onion varieties like Walla Walla, Sweet Spanish, and Ailsa Craig.
View detailed monthly data
| Month | Daylight Hours | Peak Sun Hours | Day Length |
|---|---|---|---|
| January | 9.7 hr | 5.9 hr | Short day |
| February | 10.6 hr | 6.1 hr | Short day |
| March | 11.7 hr | 7.5 hr | Short day |
| April | 13 hr | 9.1 hr | Neutral |
| May | 14 hr | 11.3 hr | Long day |
| June | 14.6 hr | 12.9 hr | Long day |
| July | 14.3 hr | 12.6 hr | Long day |
| August | 13.4 hr | 12.5 hr | Neutral |
| September | 12.2 hr | 10.2 hr | Neutral |
| October | 11 hr | 8.2 hr | Short day |
| November | 9.9 hr | 5.8 hr | Short day |
| December | 9.4 hr | 5.4 hr | Short day |
Peak sun hours factor in typical cloud cover — use these for solar panel and shade-planning calculations.
Soil Temperature & Composting Calendar
Monthly soil temps tell you when to plant warm-season crops, and when your compost pile is actively working.
Plant Warm Crops When
Soil reaches 60°F+
Soil warm enough from Mar through Dec.
Best Month to Compost
Apr
Microbial activity peaks when soil is warm.
Active Composting
12 months
Nearly year-round composting.
View detailed monthly data
| Month | Soil 4" Deep | Soil 8" Deep | Compost Activity | Time to Finish |
|---|---|---|---|---|
| Jan | 59°F | 62°F | ♻️ Active | ~14 weeks |
| Feb | 58°F | 62°F | ♻️ Active | ~14 weeks |
| Mar | 64°F | 66°F | ♻️ Active | ~14 weeks |
| Apr | 69°F | 72°F | 🔥 Peak | ~8 weeks |
| May | 78°F | 77°F | 🔥 Peak | ~8 weeks |
| Jun | 85°F | 85°F | 🔥 Peak | ~8 weeks |
| Jul | 92°F | 87°F | 🔥 Peak | ~8 weeks |
| Aug | 95°F | 90°F | 🔥 Peak | ~8 weeks |
| Sep | 91°F | 90°F | 🔥 Peak | ~8 weeks |
| Oct | 82°F | 84°F | 🔥 Peak | ~8 weeks |
| Nov | 69°F | 77°F | 🔥 Peak | ~8 weeks |
| Dec | 61°F | 68°F | ♻️ Active | ~14 weeks |
Highlighted rows = soil 60°F+ (safe for warm-season transplants). Compost finishes fastest during peak activity months.
Pest & Disease Pressure in San Mateo County
Computed from local climate patterns — warmer, humid conditions increase pest generations and fungal disease risk.
Insect Pest Pressure
High — expect multiple pest generations. Preventative measures essential.
Disease Risk
Low disease risk — dry conditions reduce fungal problems.
Seasonal Risk
View 6 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | High | Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec |
| Whiteflies | High | Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec |
| Spider mites | High | Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov |
| Thrips | High | Mar, Apr, May, Jun, Jul, Aug, Sep |
| Scale insects | Moderate | Apr, May, Jun, Jul, Aug, Sep, Oct |
| Nematodes | Moderate | May, Jun, Jul, Aug, Sep |
Organic pest management tips
- Use row covers on susceptible crops during peak pest months
- Apply neem oil preventatively every 7-14 days during active pest season
- Interplant with strong-scented herbs (basil, marigold) to confuse pests
- Hand-pick larger pests (beetles, caterpillars) in early morning when they're sluggish
- Practice crop rotation — never plant the same family in the same spot within 3 years
Cover Crops for San Mateo County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Spring Cover Crops (4 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Jan 23 | Oct 3 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Cowpeas (southern peas) | Jan 24 | Oct 17 | ✓ Yes | Excellent nitrogen fixer for warm climates, edible |
| Sorghum-sudan grass | Jan 29 | Oct 10 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Dec 22 | Oct 17 | ✓ Yes | Living mulch, fixes nitrogen, permanent ground cover |
Summer Cover Crops (1 options) — Fill gaps and suppress weeds between plantings
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Sunflowers | Feb 10 | Nov 28 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Fall Cover Crops (1 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Crimson clover | Oct 16 | Dec 28 | ✓ Yes | Fixes nitrogen, attracts pollinators in spring |
Wind & Microclimate
Wind dries soil, stresses plants, and affects frost patterns. Understanding your exposure helps with garden placement.
Seasonal Wind Speed
Spring: 13 mph Summer: 10 mph
Fall: 7 mph Winter: 9 mph
Prevailing wind: W. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
5.1/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Moderate
Some terrain variation (642 ft range). Garden on slopes or higher ground if possible to avoid late-season frost pockets.
Rainwater Harvesting Potential
How much water you can collect, when to collect it, and what size system you need for your garden.
Annual Collection
8,422 gal
Per 1,000 sq ft of roof area (at 80% collection efficiency)
Recommended Setup
8 rain barrels (55 gal each)
For a typical 500 sq ft garden. Serious collectors: consider a 2,500 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
Jan, Feb, Mar, Dec
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
May, Jun, Jul, Aug, Sep, Oct
Dry months when you'll rely on stored water — size your storage for this gap.
Rainwater collection tips for your area
- Your county receives approximately 16.9 inches of rain per year
- A 1,000 sq ft roof can collect roughly 8,422 gallons annually
- Rainwater harvesting is fully legal in your state
- In your dry climate, every drop counts — consider a larger cistern system
- Position collection tanks in shade to reduce evaporation and algae growth
Soil & Growing Conditions in San Mateo County
Soil Type
Loam
Soil pH 6.8–7.2 · Excessively Drained drainage
Native soil is well-suited to most vegetables and herbs with regular compost additions.
Watering Needs
Drought stress: 7.5/10
High drought stress. Consistent irrigation is essential — consider drip systems, heavy mulch, and drought-tolerant varieties.
Season Tips
329-day frost-free season
Your long season supports multiple successions and heat-demanding crops like melons, sweet potatoes, and peppers. Plant warm-season crops as soon as soil warms.
Your Free Printable Garden Planner
Plan every bed, every planting, every harvest — in one place. This 24-page printable includes your zone's planting calendar, a month-by-month task list, a seed inventory tracker, a harvest log, and succession-planting charts. Built to print, write in, and actually use all season.
Recommended for Your Garden
Reduce heat stress and sun scorch in hot climates with UV-stabilized shade cloth.
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Get instant, accurate soil pH readings to fine-tune your amendments.
🥬 Vegetables to Grow in San Mateo County
106 vegetables that grow well in Zone 10a with planting dates for San Mateo County.
Show all 106 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Dec 21 | Jan 18 | Jan 25 | Apr 19 – May 24 | 80–100 |
| Amaranth | Dec 7 | Jan 18 | Jan 25 | Apr 26 – Jun 14 | 90–120 |
| Artichoke | — | — | Feb 1 | Jun 7 – Aug 16 | 120–180 |
| Arugula | Dec 21 | Dec 28 | Jan 18 | Feb 22 – Apr 26 | 30–50 |
| Asparagus | — | — | Feb 1 | — | 730–1095 |
| Beets | — | Dec 28 | — | Feb 22 – Mar 22 | 50–70 |
| Belgian Endive | Dec 21 | Dec 28 | Jan 18 | May 10 – Jul 5 | 110–150 |
| Bitter Melon | Dec 7 | Jan 18 | Jan 25 | Mar 29 – May 10 | 60–90 |
| Black Beans | — | Jan 25 | — | Apr 26 – Jun 14 | 90–120 |
| Bok Choy | Dec 21 | Dec 28 | Jan 18 | Mar 1 – Apr 5 | 40–60 |
| Broccoli | Dec 21 | Dec 28 | Jan 18 | Mar 22 – May 3 | 60–90 |
| Broccoli Rabe | Dec 21 | Dec 28 | Jan 18 | Mar 1 – Apr 5 | 40–60 |
| Brussels Sprouts | Dec 21 | Dec 28 | Jan 18 | Apr 19 – Jun 14 | 90–130 |
| Butternut Squash | Dec 21 | Jan 18 | Jan 25 | Apr 26 – May 31 | 85–110 |
| Cabbage | Dec 21 | Dec 28 | Jan 18 | Mar 22 – May 17 | 60–100 |
| Calabash | Dec 7 | Jan 18 | Jan 25 | Apr 19 – Jun 14 | 80–120 |
| Cardoon | — | — | Feb 1 | Jun 7 – Jul 19 | 120–150 |
| Carrots | — | Dec 28 | — | Mar 1 – Apr 5 | 60–80 |
| Cauliflower | Dec 21 | Dec 28 | Jan 18 | Mar 15 – May 17 | 55–100 |
| Celery | Dec 21 | Dec 28 | Jan 18 | Apr 12 – Jun 7 | 80–120 |
| Celtuce | Dec 21 | Dec 28 | Jan 18 | Mar 22 – May 3 | 60–90 |
| Chard | Dec 21 | Dec 28 | Jan 18 | Mar 15 – May 3 | 50–60 |
| Chayote | Dec 7 | Jan 18 | Jan 25 | May 31 – Aug 9 | 120–180 |
| Chickpeas | Dec 21 | Dec 28 | Jan 18 | Apr 12 – May 24 | 80–110 |
| Chicory | Dec 21 | Dec 28 | Jan 18 | Mar 22 – May 3 | 60–85 |
| Chinese Cabbage | Dec 21 | Dec 28 | Jan 18 | Mar 15 – Apr 12 | 50–70 |
| Christmas Lima Beans | Dec 7 | Jan 18 | Jan 25 | Apr 19 – May 24 | 80–100 |
| Collard Greens | Dec 21 | Dec 28 | Jan 18 | Mar 15 – May 17 | 55–75 |
| Corn | — | Jan 25 | — | Mar 29 – May 24 | 60–100 |
| Cowpeas | — | Jan 25 | — | Mar 29 – May 10 | 60–90 |
| Cress | Dec 21 | Dec 28 | Jan 18 | Feb 1 – Feb 22 | 14–21 |
| Crookneck Squash | Dec 21 | Jan 18 | Jan 25 | Mar 15 – Apr 12 | 45–60 |
| Cucumber | Dec 21 | Jan 18 | Jan 25 | Mar 22 – May 17 | 50–70 |
| Daikon | — | Dec 28 | — | Feb 22 – Mar 22 | 50–70 |
| Delicata Squash | Dec 21 | Jan 18 | Jan 25 | Apr 19 – May 24 | 80–100 |
| Edamame | — | Jan 25 | — | Apr 12 – May 24 | 75–100 |
| Eggplant | Dec 7 | Jan 18 | Jan 25 | Apr 5 – Jun 7 | 65–85 |
| Endive | Dec 21 | Dec 28 | Jan 18 | Mar 8 – Apr 12 | 45–65 |
| Escarole | Dec 21 | Dec 28 | Jan 18 | Mar 15 – Apr 12 | 50–70 |
| Fava Beans | Dec 21 | Dec 28 | Jan 18 | Apr 5 – May 17 | 75–100 |
| Fennel | Dec 7 | Jan 18 | Jan 25 | Mar 29 – May 10 | 60–90 |
| Ginger | Dec 7 | Jan 18 | Jan 25 | Sep 27 – Dec 6 | 240–300 |
| Green Beans | — | Jan 25 | — | Mar 22 – May 17 | 50–65 |
| Hot Peppers | Dec 7 | Jan 18 | Jan 25 | Apr 5 – Jul 12 | 70–120 |
| Hubbard Squash | Dec 21 | Jan 18 | Jan 25 | May 10 – Jun 14 | 100–120 |
| Jicama | Dec 7 | Jan 18 | Jan 25 | May 31 – Aug 9 | 120–180 |
| Kabocha | Dec 21 | Jan 18 | Jan 25 | Apr 26 – May 24 | 85–100 |
| Kai Lan | Dec 21 | Dec 28 | Jan 18 | Mar 8 – Apr 5 | 45–60 |
| Kale | Dec 21 | Dec 28 | Jan 18 | Mar 15 – May 10 | 50–70 |
| Kidney Beans | — | Jan 25 | — | Apr 26 – May 31 | 85–110 |
| Kohlrabi | Dec 21 | Dec 28 | Jan 18 | Mar 8 – Apr 12 | 45–65 |
| Komatsuna | Dec 21 | Dec 28 | Jan 18 | Feb 22 – Mar 29 | 35–50 |
| Leeks | Dec 21 | Dec 28 | Jan 18 | Apr 19 – Jul 5 | 90–150 |
| Lentils | Dec 21 | Dec 28 | Jan 18 | Apr 12 – May 24 | 80–110 |
| Lettuce | Dec 21 | Dec 28 | Jan 18 | Feb 22 – May 3 | 30–60 |
| Lima Beans | — | Jan 25 | — | Mar 29 – May 10 | 60–90 |
| Loofah | Dec 7 | Jan 18 | Jan 25 | May 10 – Jul 12 | 100–150 |
| Luffa | Dec 7 | Jan 18 | Jan 25 | Apr 26 – Jul 12 | 90–150 |
| Mache | Dec 21 | Dec 28 | Jan 18 | Mar 1 – Apr 5 | 40–60 |
| Malabar Spinach | Dec 7 | Jan 18 | Jan 25 | Mar 22 – Apr 19 | 55–70 |
| Melon | Dec 21 | Jan 18 | Jan 25 | Apr 5 – May 24 | 70–100 |
| Microgreens | Dec 21 | Dec 28 | Jan 18 | Jan 25 – Feb 22 | 7–21 |
| Mizuna | Dec 21 | Dec 28 | Jan 18 | Feb 22 – Mar 22 | 30–45 |
| Mustard Greens | Dec 21 | Dec 28 | Jan 18 | Feb 22 – Apr 26 | 30–50 |
| Napa Cabbage | Dec 21 | Dec 28 | Jan 18 | Mar 15 – Apr 19 | 55–75 |
| New Zealand Spinach | Dec 7 | Jan 18 | Jan 25 | Mar 22 – Apr 19 | 55–70 |
| Okra | Dec 7 | Jan 18 | Jan 25 | Mar 22 – May 17 | 50–65 |
| Onion | Dec 21 | Dec 28 | Jan 18 | Apr 19 – Jun 7 | 90–120 |
| Pac Choi | Dec 21 | Dec 28 | Jan 18 | Mar 1 – Mar 29 | 40–55 |
| Patty Pan Squash | Dec 21 | Jan 18 | Jan 25 | Mar 15 – Apr 12 | 45–60 |
| Peas | Dec 21 | Dec 28 | Jan 18 | Mar 15 – May 10 | 55–70 |
| Peppers | Dec 7 | Jan 18 | Jan 25 | Mar 29 – Jun 7 | 60–90 |
| Pole Beans | Dec 7 | Jan 18 | Jan 25 | Mar 22 – May 17 | 55–70 |
| Potatoes | Dec 7 | Jan 18 | Jan 25 | Apr 5 – Jun 14 | 70–120 |
| Pumpkin | Dec 21 | Jan 18 | Jan 25 | Apr 26 – Jun 14 | 85–120 |
| Purslane | Dec 21 | Dec 28 | Jan 18 | Mar 1 – Apr 5 | 40–60 |
| Radicchio | Dec 21 | Dec 28 | Jan 18 | Mar 22 – Apr 26 | 60–80 |
| Radish | — | Dec 28 | — | Jan 25 – Feb 15 | 22–35 |
| Romanesco | Dec 21 | Dec 28 | Jan 18 | Apr 5 – May 17 | 75–100 |
| Savoy Cabbage | Dec 21 | Dec 28 | Jan 18 | Mar 29 – May 24 | 70–110 |
| Scallions | Dec 21 | Dec 28 | Jan 18 | Mar 15 – Apr 12 | 50–70 |
| Scarlet Runner Beans | Dec 7 | Jan 18 | Jan 25 | Mar 29 – May 3 | 60–80 |
| Shallot | Dec 21 | Dec 28 | Jan 18 | Apr 19 – Jun 7 | 90–120 |
| Shiso | Dec 7 | Jan 25 | Jan 25 | Mar 22 – May 17 | 50–70 |
| Snap Peas | Dec 7 | Jan 18 | Jan 25 | Mar 22 – May 17 | 55–70 |
| Snow Peas | Dec 21 | Dec 28 | Jan 18 | Mar 15 – May 10 | 50–65 |
| Soybeans | — | Jan 25 | — | Apr 19 – Jun 14 | 80–120 |
| Spaghetti Squash | Dec 21 | Jan 18 | Jan 25 | Apr 26 – May 24 | 85–100 |
| Spinach | Dec 21 | Dec 28 | Jan 18 | Feb 22 – Apr 26 | 35–50 |
| Squash (Summer) | Dec 21 | Jan 18 | Jan 25 | Mar 15 – May 17 | 45–65 |
| Squash (Winter) | Dec 21 | Jan 18 | Jan 25 | Apr 19 – Jun 14 | 80–120 |
| Sunflower | Dec 7 | Jan 18 | Jan 25 | Apr 5 – May 24 | 70–100 |
| Sweet Corn | — | Jan 25 | — | Mar 29 – May 10 | 60–90 |
| Sweet Potatoes | Dec 7 | Jan 18 | Jan 25 | Apr 26 – Jun 14 | 90–120 |
| Tatsoi | Dec 21 | Dec 28 | Jan 18 | Feb 22 – Mar 29 | 35–50 |
| Tomatillo | Dec 7 | Jan 18 | Jan 25 | Mar 29 – Jun 7 | 60–85 |
| Tomatoes | Dec 7 | Jan 18 | Jan 25 | Mar 29 – Jun 7 | 60–85 |
| Turmeric | Dec 7 | Jan 18 | Jan 25 | Sep 27 – Dec 6 | 240–300 |
| Turnip | — | Dec 28 | — | Feb 8 – Mar 15 | 40–60 |
| Watercress | Dec 21 | Dec 28 | Jan 18 | Mar 1 – Apr 5 | 40–60 |
| Watermelon | Dec 21 | Jan 18 | Jan 25 | Apr 5 – May 24 | 70–100 |
| Wax Beans | — | Jan 25 | — | Mar 22 – May 17 | 50–65 |
| Winter Melon | Dec 7 | Jan 18 | Jan 25 | Apr 26 – Jun 14 | 90–120 |
| Yam | Dec 7 | Jan 18 | Jan 25 | Jul 26 – Jan 10 | 180–330 |
| Yard Long Beans | Dec 7 | Jan 18 | Jan 25 | Mar 22 – May 3 | 55–80 |
| Zucchini | Dec 21 | Jan 18 | Jan 25 | Mar 15 – May 10 | 45–60 |
🍓 Fruits to Grow in San Mateo County
16 fruits that grow well in Zone 10a with planting dates for San Mateo County.
Show all 16 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Feb 1 | May 3 – Aug 16 | 90–180 |
| Blackberries | — | — | Feb 1 | — | 365–730 |
| Boysenberries | — | — | Feb 1 | — | 365–730 |
| Cantaloupe | — | — | Feb 1 | Apr 12 – May 17 | 70–90 |
| Che Fruit | — | — | Feb 1 | — | 1095–1825 |
| Dragon Fruit | — | — | Feb 1 | — | 365–730 |
| Figs | — | — | Feb 1 | — | 730–1825 |
| Goji Berries | — | — | Feb 1 | — | 730–1095 |
| Grapes | — | — | Feb 1 | — | 730–1095 |
| Ground Cherry | — | — | Feb 1 | Apr 12 – Jun 7 | 65–80 |
| Guava | — | — | Feb 1 | — | 365–730 |
| Honeydew | — | — | Feb 1 | Apr 26 – Jun 7 | 80–110 |
| Loquat | — | — | Feb 1 | — | 730–1825 |
| Passion Fruit | — | — | Feb 1 | — | 365–545 |
| Pomegranate | — | — | Feb 1 | — | 730–1095 |
| Strawberries | — | — | Feb 1 | May 3 – Jan 31 | 90–365 |
🌿 Herbs to Grow in San Mateo County
23 herbs that grow well in Zone 10a with planting dates for San Mateo County.
Show all 23 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Anise | Dec 21 | Dec 28 | Jan 11 | Apr 12 – Jun 28 | 90–120 |
| Basil | Dec 7 | Jan 25 | Jan 25 | Mar 22 – May 24 | 50–75 |
| Borage | Dec 21 | Dec 28 | Jan 11 | Mar 8 – Apr 26 | 50–60 |
| Chervil | Dec 21 | Dec 28 | Jan 11 | Feb 22 – Apr 26 | 40–60 |
| Chives | — | — | Jan 25 | Mar 29 – Jun 7 | 60–90 |
| Cilantro | Dec 21 | Dec 28 | Jan 11 | Feb 22 – Apr 26 | 40–60 |
| Cumin | Dec 21 | Dec 28 | Jan 11 | Apr 26 – Jun 28 | 100–120 |
| Dill | Dec 21 | Dec 28 | Jan 11 | Feb 22 – Apr 26 | 40–60 |
| Epazote | Dec 7 | Jan 25 | Jan 25 | Mar 15 – May 10 | 45–60 |
| Fennel (herb) | Dec 21 | Dec 28 | Jan 11 | Mar 15 – May 24 | 60–90 |
| Garlic Chives | — | — | Jan 25 | Mar 29 – Jun 7 | 60–90 |
| Horehound | — | — | Jan 25 | Apr 12 – Jun 7 | 75–90 |
| Lemon Verbena | Dec 7 | Jan 25 | Jan 25 | Mar 29 – Jun 7 | 60–90 |
| Lemongrass | Dec 7 | Jan 25 | Jan 25 | Apr 12 – Jul 12 | 75–120 |
| Marjoram | — | — | Jan 25 | Mar 29 – Jun 7 | 60–90 |
| Mint | — | — | Jan 25 | Mar 29 – Jun 7 | 60–90 |
| Oregano | — | — | Jan 25 | Mar 29 – Jun 7 | 60–90 |
| Parsley | Dec 21 | Dec 28 | Jan 11 | Mar 15 – May 17 | 60–80 |
| Rosemary | — | — | Jan 25 | Apr 19 – Sep 6 | 80–180 |
| Sage | — | — | Jan 25 | Apr 12 – Jun 7 | 75–90 |
| Savory | — | — | Jan 25 | Mar 22 – May 17 | 50–70 |
| Stevia | Dec 7 | Jan 25 | Jan 25 | Mar 29 – Jun 7 | 60–90 |
| Thai Basil | Dec 7 | Jan 25 | Jan 25 | Mar 22 – May 24 | 50–75 |
Monthly Planting Guide for San Mateo County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in San Mateo County.
Frequently Asked Questions
What planting zone is San Mateo County, CA?
San Mateo County is in USDA Hardiness Zone 10a. This zone classification determines which perennial plants survive winter and sets the baseline for frost timing across the county.
When is the last frost in San Mateo County, CA?
Based on 13 years of NOAA weather station data, the median last spring frost in San Mateo County falls around January 18. In 8 out of 10 years, last frost lands between January 5 and March 24 — a 79-day window of variability. Use March 24 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in San Mateo County, CA?
The median first fall frost in San Mateo County arrives around December 12. In cold years it can arrive as early as November 22; in mild years as late as December 24. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in San Mateo County?
San Mateo County has a frost-free growing season of approximately 329 days. This long season supports multiple succession plantings and warm-season crops that need extended heat, like sweet potatoes and melons. Climate records show the growing season is trending longer by about 25.71 days per decade.
What is the soil like in San Mateo County for gardening?
San Mateo County has predominantly Loam soil with a pH range of 6.8–7.2 and Excessively Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in San Mateo County?
San Mateo County has commercial agriculture that includes Almonds, Dairy, Grapes, Lettuce, Walnuts. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is San Mateo County a good location for home gardening?
San Mateo County scores 44/100 (Moderate) on our Microclimate Index, which combines frost reliability, drought pressure, soil challenge, elevation risk, and long-term climate trend. Gardening here benefits from close attention to frost timing and season extension due to the challenging microclimate factors.
Your San Mateo County Garden Planner — Free
A 24-page printable planner built for San Mateo County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.
The Gardener's Encyclopedia to Companion Planting
The pairings that make vegetables, herbs, and flowers grow better — and the ones that quietly wreck a bed.
- Proven pairings for 200+ vegetables, herbs, flowers, and fruits
- Full seed-starting + planting schedule with timing and spacing
- Bonus: square-foot gardening guide + printable seasonal planners
Seed Saving & Storage Guide
Most saved seeds go bad before next season. This shows exactly when to pick, how to dry, and where to store seeds from 200 plants so yours don't.
- 200 plants, step-by-step: life cycle, pollination type, isolation
- Exact temperature + humidity ranges that keep seeds viable
- Bonus: searchable Google Sheets tracker + custom GPT assistant
Composting Guide for Homesteaders
Turn kitchen scraps and yard waste into compost that actually feeds the garden — instead of a pile that smells, attracts pests, and never breaks down.
- 14 sections on composting methods, soil science, and troubleshooting
- The 7-step hot-compost system from start to finish
- Bonus tools: troubleshooting chart, safety guide, monitoring log