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When to Plant Lemon Verbena in San Diego County, CA

San Diego County, California Zone 10b May

May in San Diego County, California — your action list

We've pulled the most time-sensitive tasks for San Diego County, California this May and put them front and centre. Tackle them in order.

Avg. last frost April 16
Avg. first frost November 1
Soil temp (4") 74°F
Watering Critical
Pest pressure High
Daylight 13.7 hrs
  1. Start lemon verbena indoors

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

Before June arrives, get these ready
  • First harvests: lemon verbena

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Lemon verbena is a deciduous shrub with intensely lemon-scented leaves that retain their aroma when dried. It makes an exceptional tea and adds citrus flavor to dishes.

San Diego County, California is in USDA Zone 10b. The average last spring frost is April 16 and the first fall frost is November 1, giving you a growing season of approximately 199 days.

At an elevation of 2,613 feet, San Diego County receives approximately 18.2 inches of rainfall annually with predominantly loam soil. Summer highs average 92°F, providing good warmth for Lemon Verbena during the growing season. With low rainfall, drip irrigation is essential for growing Lemon Verbena successfully. Mulch heavily to conserve soil moisture.

San Diego County, CA (Zone 10b) Moderate season
199 days
Last Spring Frost April 16
199 growing days
First Fall Frost November 1

San Diego County Soil Profile

Soil Type

Loam

Soil pH

5.7-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (54 days to spare)
Start indoors: Feb 26 Transplant: Apr 16 🍅 Harvest: Jun 18 – Aug 27
Recommended (50%) ✓ Fits season (59 days to spare)
Start indoors: Mar 5 Transplant: Apr 23 🍅 Harvest: Jun 25 – Sep 3
Safe Start (90%) ✓ Fits season (55 days to spare)
Start indoors: Apr 9 Transplant: May 28 🍅 Harvest: Jul 30 – Oct 8

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 Diego County

How your county's soil matches Lemon Verbena's growing requirements.

Soil pH

Your soil pH (5.7–7.5) overlaps with Lemon Verbena's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Lemon Verbena.

How to Plant Lemon Verbena

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

Succession Planting Lemon Verbena

3
successive plantings in your 199-day season

Sow every 6.9 weeks. Last sowing by Aug 03 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.4″/week
You supply
0.7″/week
Watering frequency 2-3 times/week
Season total 1,309 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Lemon Verbena

Lemon Verbena needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Lemon Verbena Needs Rainfall You Supplement Action
Jan 3" 0" ❄️ Dormant
Feb 3.9" 0" ❄️ Dormant
Mar 3.1" 0" ❄️ Dormant
Apr 4.3" 1.4" 2.9" 🚿 Regular watering
May 4.3" 0.5" 3.8" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 0.8" 3.5" 🚿 Regular watering
Nov 4.3" 1.8" 2.5" 🚿 Regular watering
Dec 3.3" 0" ❄️ Dormant

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

Lemon Verbena 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.

Lemon Verbena needs ~1,425 GDD — county provides 3,781 GDD Excellent fit

Lemon Verbena Planting Timeline — San Diego County, CA

Lemon Verbena Planting Calendar

Activity When Date Range
Start Indoors March 5 Mar 5 – Mar 19
Transplant Outdoors April 23 Apr 23 – May 7
Direct Sow April 23 Apr 23 – May 14
Harvest June 25 Jun 25 – Sep 3

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 10b

📆 Growing Season

199 days in San Diego County

Growing Tips for Lemon Verbena in San Diego County

Direct sow Lemon Verbena outdoors after April 16 in San Diego County when soil has warmed and frost danger has passed.

San Diego County receives only 18" of rain annually. Lemon Verbena needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Grow in a container in cold climates and bring indoors for winter. Prune back hard in spring. Harvest leaves anytime but flavor peaks just before flowering. Dries well for tea.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemon Verbena in San Diego County, CA?

San Diego County is in Zone 10b with an average last frost of April 16. Plan your Lemon Verbena planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Diego County, CA?

San Diego County, California is in USDA Hardiness Zone 10b. The average last spring frost is April 16 and first fall frost is November 1.

🌱

Your San Diego County Garden Planner — Free

A 24-page printable planner built for San Diego County (Zone 10b). 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 Diego 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.