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When to Plant Sage in San Mateo County, CA

San Mateo County, California Zone 10a May

This month in San Mateo County, California

A quick May briefing for San Mateo County, California gardeners — what's urgent, what's next, and what can wait.

Avg. last frost January 18
Avg. first frost December 12
Soil temp (4") 78°F
Watering Critical
Pest pressure High
Daylight 14 hrs
  1. Bring in the sage

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

June will be here before you know it — start on
  • First harvests: sage

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Sage is a woody perennial herb with velvety gray-green leaves and a warm, peppery flavor. It is a traditional seasoning for poultry, stuffing, and sausage.

San Mateo County, California 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 328 days.

At an elevation of 277 feet, San Mateo County receives approximately 16.9 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Sage to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Sage successfully. Mulch heavily to conserve soil moisture.

San Mateo County, CA (Zone 10a) Year-round
328 days
Last Spring Frost January 18
328 growing days
First Fall Frost December 12

San Mateo County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (185 days to spare)
Transplant: Jan 21 🍅 Harvest: Apr 8 – Jun 3
Recommended (50%) ✓ Fits season (188 days to spare)
Transplant: Jan 25 🍅 Harvest: Apr 12 – Jun 7
Safe Start (90%) ✓ Fits season (135 days to spare)
Transplant: Mar 31 🍅 Harvest: Jun 16 – Aug 11

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in San Mateo County

How your county's soil matches Sage's growing requirements.

Soil pH

Your soil pH (6.8–7.2) overlaps with Sage's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in San Mateo County is excellent for Sage — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Sage.

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Sage.

How to Plant Sage

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Sage

5
successive plantings in your 328-day season

Sow every 8.6 weeks. Last sowing by Sep 13 to harvest before frost.

Plant Water Budget

Plant needs
0.3″/week
Rainfall provides
0.2″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 612 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Sage

Sage needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.

Month Sage Needs Rainfall You Supplement Action
Jan 1.3" 3.9" 0" ✅ Rainfall sufficient
Feb 1.3" 3.4" 0" ✅ Rainfall sufficient
Mar 1.3" 2.7" 0" ✅ Rainfall sufficient
Apr 1.3" 1.2" 0.1" 💧 Light watering
May 1.3" 0.4" 0.9" 🚿 Regular watering
Jun 1.3" 0.1" 1.2" 🚿 Regular watering
Jul 1.3" 0" 1.3" 🚿 Regular watering
Aug 1.3" 0" 1.3" 🚿 Regular watering
Sep 1.3" 0.2" 1.1" 🚿 Regular watering
Oct 1.3" 0.7" 0.6" 💧 Light watering
Nov 1.3" 1.4" 0" ✅ Rainfall sufficient
Dec 1.3" 2.9" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Jan–Dec in San Mateo County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Sage Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Sage needs ~887 GDD — county provides 3,536 GDD Excellent fit

Sage Planting Timeline — San Mateo County, CA

Sage Planting Calendar

Activity When Date Range
Transplant Outdoors January 25 Jan 25 – Feb 8
Harvest April 12 Apr 12 – Jun 7

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January Transplant Outdoors
February Transplant Outdoors
March
April Harvest
May Harvest
June Harvest
July
August
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Only during dry spells

📅 Days to Maturity

75–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

328 days in San Mateo County

Growing Tips for Sage in San Mateo County

Direct sow Sage outdoors after January 18 in San Mateo County when soil has warmed and frost danger has passed.

General growing tips

Start from seed or cuttings. Prune after flowering to maintain shape. Replace plants every 4-5 years when they become woody and less productive. Excellent drainage is essential.

Companion Planting

Good Companions

Avoid Planting Near

  • Cucumber
  • Rue

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sage in San Mateo County, CA?

San Mateo County is in Zone 10a with an average last frost of January 18. Plan your Sage planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Mateo County, CA?

San Mateo County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 18 and first fall frost is December 12.

🌱

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.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for San Mateo County, CA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.