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When to plant Borage in Pacifica, CA

Borage planted in Pacifica between December 28 and January 18 matures in 50–60 days — well before the December 12 first frost. A second sowing from October 17 to October 31 extends the harvest into fall.

When to Plant Borage in Pacifica, CA

San Mateo County, California Zone 10a June

Your June gardening checklist

Here's what deserves your attention in San Mateo County, California this month. Everything below is tailored to Zone 10a and timed around your local frost dates.

Avg. last frost January 18
Avg. first frost December 12
Soil temp (4") 85°F
Watering Critical
Pest pressure High
Daylight 14.6 hrs
  1. Survive, don't thrive

    June-August is endurance gardening. Keep okra, peppers, sweet potatoes, and southern peas alive. Harvest everything daily before the heat damages produce on the vine.

  2. Start fall tomato seeds indoors

    Yes, indoors — under lights or in AC. They'll be ready to transplant in August when temperatures briefly moderate.

  3. Add compost to empty beds

    Empty beds get a thick layer of compost + mulch to suppress weeds and feed the soil for fall planting.

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Borage is a self-seeding annual herb with star-shaped blue flowers that attract pollinators. Its leaves have a cucumber-like flavor and the flowers are edible.

Pacifica, 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 Borage to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Borage successfully. Mulch heavily to conserve soil moisture.

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

Pacifica Soil Profile

Soil Type

Loam

Soil pH

6.8-7.2

Drainage

Well Drained

Borage Planting Risk Windows

Early Start (70% safe) ✓ Fits season (227 days to spare)
Start indoors: Dec 17 Transplant: Jan 7 🍅 Harvest: Mar 4 – Apr 22
Recommended (50%) ✓ Fits season (230 days to spare)
Start indoors: Dec 21 Transplant: Jan 11 🍅 Harvest: Mar 8 – Apr 26
Safe Start (90%) ✓ Fits season (177 days to spare)
Start indoors: Feb 24 Transplant: Mar 17 🍅 Harvest: May 12 – Jun 30

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 Pacifica

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

Soil pH

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

Soil Texture

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

Drainage

Drainage is adequate for Borage.

Organic Matter

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

How to Plant Borage

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

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Borage

7
successive plantings in your 328-day season

Sow every 5.7 weeks. Last sowing by Oct 13 to harvest before frost.

For a dedicated fall crop, sow by Oct 17.

Borage Water Budget

Plant needs
0.5″/week
Rainfall provides
0.2″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 1,526 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Borage

Borage needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Borage Needs Rainfall You Supplement Action
Jan 2.2" 3.9" 0" ✅ Rainfall sufficient
Feb 2.2" 3.4" 0" ✅ Rainfall sufficient
Mar 2.2" 2.7" 0" ✅ Rainfall sufficient
Apr 2.2" 1.2" 1" 💧 Light watering
May 2.2" 0.4" 1.8" 🚿 Regular watering
Jun 2.2" 0.1" 2.1" 🚿 Regular watering
Jul 2.2" 0" 2.2" 🚿 Regular watering
Aug 2.2" 0" 2.2" 🚿 Regular watering
Sep 2.2" 0.2" 2" 🚿 Regular watering
Oct 2.2" 0.7" 1.5" 🚿 Regular watering
Nov 2.2" 1.4" 0.8" 💧 Light watering
Dec 2.2" 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.

Borage 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.

Borage needs ~591 GDD — county provides 3,536 GDD Excellent fit

Borage Planting Timeline — Pacifica, CA

Borage Planting Calendar

Activity When Date Range
Start Indoors December 21 Dec 21 – Jan 4
Transplant Outdoors January 11 Jan 11 – Jan 25
Direct Sow December 28 Dec 28 – Jan 18
Harvest March 8 Mar 8 – Apr 26
Fall Sowing October 17 Oct 17 – Oct 31

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

Month-by-Month Timeline

MonthActivities
January Start Indoors Transplant Outdoors Direct Sow
February
March Harvest
April Harvest
May
June
July
August
September
October Fall Sowing
November
December Start Indoors Direct Sow

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · 1-2 times/week

📅 Days to Maturity

50–60 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

328 days in San Mateo County

Growing Tips for Borage in Pacifica

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

General growing tips

Direct sow in spring as borage does not transplant well. Allow some plants to go to seed for next year. Young leaves are best; older leaves become bristly.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

When should I plant Borage in Pacifica, CA?

In Pacifica, CA, plant Borage after the last frost (around January 18) and before the first frost (around December 12). Best results when soil holds above 50°F.

What growing zone is Pacifica, CA for Borage?

Pacifica sits in USDA Zone 10a. Borage grows reliably in zones 3a through 11b, so it's a good fit here.

Can Borage grow in Pacifica's climate?

Yes — Borage grows well in Pacifica's temperate climate. Pacifica averages a 329-day frost-free season, with last frost around January 18 and first frost around December 12.

🌱

Your San Mateo County Garden Planner — Free

A 22-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: June 2026.