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When to Plant Lemongrass in Marin County, CA

Marin County, California Zone 9b May

May in Marin County, California — your action list

May is a pivotal month for Marin County, California gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost February 26
Avg. first frost November 26
Soil temp (4") 79°F
Watering Critical
Pest pressure High
Daylight 14.1 hrs
  1. Bring in the lemongrass

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

June prep starts now
  • First harvests: lemongrass

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Lemongrass is a tropical grass with a strong citrus aroma used extensively in Southeast Asian cuisine. The swollen stem bases are the most flavorful part.

Marin County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 26, giving you a growing season of approximately 273 days.

At an elevation of 302 feet, Marin County receives approximately 36 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 81°F, so choose short-season varieties of Lemongrass to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Lemongrass will need more frequent watering and organic matter to retain nutrients.

Marin County, CA (Zone 9b) Year-round
273 days
Last Spring Frost February 26
273 growing days
First Fall Frost November 26
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Marin County Soil Profile

Soil Type

Sandy Loam

Soil pH

6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (110 days to spare)
Start indoors: Dec 30 Transplant: Feb 17 🍅 Harvest: May 5 – Aug 4
Recommended (50%) ✓ Fits season (98 days to spare)
Start indoors: Jan 15 Transplant: Mar 5 🍅 Harvest: May 21 – Aug 20
Safe Start (90%) ✓ Fits season (84 days to spare)
Start indoors: Feb 19 Transplant: Apr 9 🍅 Harvest: Jun 25 – Sep 24

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 Marin County

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

Soil pH

Your soil pH (6.0–6.9) is within Lemongrass's preferred range (5.5–7.5).

Soil Texture

Sandy soil in Marin County warms quickly in spring but drains fast. Lemongrass will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Lemongrass.

How to Plant Lemongrass

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

Succession Planting Lemongrass

4
successive plantings in your 273-day season

Sow every 8.6 weeks. Last sowing by Jul 29 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.6″/week
You supply
1.1″/week
Watering frequency 2-3 times/week
Season total 2,775 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Lemongrass

Lemongrass needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Lemongrass Needs Rainfall You Supplement Action
Jan 7.2" 0" ❄️ Dormant
Feb 6.5" 6.5" 0" ✅ Rainfall sufficient
Mar 6.5" 6.2" 0.3" 💧 Light watering
Apr 6.5" 2.7" 3.8" 🚿 Regular watering
May 6.5" 1" 5.5" 🚿 Regular watering
Jun 6.5" 0.2" 6.3" 🚿 Regular watering
Jul 6.5" 0" 6.5" 🚿 Regular watering
Aug 6.5" 0" 6.5" 🚿 Regular watering
Sep 6.5" 0.4" 6.1" 🚿 Regular watering
Oct 6.5" 1.4" 5.1" 🚿 Regular watering
Nov 6.5" 3.5" 3" 💧 Light watering
Dec 6.9" 0" ❄️ Dormant

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

Lemongrass 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.

Lemongrass needs ~1,048 GDD — county provides 2,945 GDD Excellent fit

Lemongrass Planting Timeline — Marin County, CA

Lemongrass Planting Calendar

Activity When Date Range
Start Indoors January 15 Jan 15 – Jan 29
Transplant Outdoors March 5 Mar 5 – Mar 19
Direct Sow March 5 Mar 5 – Mar 26
Harvest May 21 May 21 – Aug 20

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

75–120 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 9b

📆 Growing Season

273 days in Marin County

Growing Tips for Lemongrass in Marin County

Direct sow Lemongrass outdoors after February 26 in Marin County when soil has warmed and frost danger has passed.

Sandy soil in Marin County dries quickly — mulch Lemongrass with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Common pests for Lemongrass in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.

General growing tips

Start from divisions or store-bought stalks rooted in water. Grow in rich, moist soil with full sun. In cold climates, grow in containers and overwinter indoors.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemongrass in Marin County, CA?

Marin County is in Zone 9b with an average last frost of February 26. Plan your Lemongrass planting based on this frost date — see the calendar above for exact timing.

What planting zone is Marin County, CA?

Marin County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 26.

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Your Marin County Garden Planner — Free

A 24-page printable planner built for Marin County (Zone 9b). 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 Marin 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.