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When to Plant Lemongrass in Humboldt County, CA

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.

Humboldt County, California is in USDA Zone 9a. The average last spring frost is February 27 and the first fall frost is November 28, giving you a growing season of approximately 274 days.

At an elevation of 148 feet, Humboldt County receives approximately 22.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87ยฐF, providing good warmth for Lemongrass during the growing season. Sandy soil warms quickly in spring โ€” great for early planting โ€” but Lemongrass will need more frequent watering and organic matter to retain nutrients.

Humboldt County, CA (Zone 9a) Year-round
274 days
Last Spring Frost February 27
274 growing days
First Fall Frost November 28

Humboldt County Soil Profile

Soil Type

Sandy Loam

Soil pH

6.2-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (108 days to spare)
Start indoors: Jan 2 Transplant: Feb 20 🍅 Harvest: May 8 – Aug 7
Recommended (50%) ✓ Fits season (99 days to spare)
Start indoors: Jan 16 Transplant: Mar 6 🍅 Harvest: May 22 – Aug 21
Safe Start (90%) ✓ Fits season (85 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.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.3″/week
You supply
1.2″/week
Watering frequency 2-3 times/week
Season total 2,845 gal / 100 sq ft
Lemongrass needs ~1,487 GDD — county provides 4,193 GDD Excellent fit

Lemongrass Planting Timeline โ€” Humboldt County, CA

Lemongrass Planting Calendar

Activity When Date Range
Start Indoors January 16 Jan 16 โ€“ Jan 30
Transplant Outdoors March 6 Mar 6 โ€“ Mar 20
Direct Sow March 6 Mar 6 โ€“ Mar 27
Harvest May 22 May 22 โ€“ Aug 21

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

75โ€“120 days

Soil pH

5.5 โ€“ 7.5

USDA Zone

Zone 9a

Growing Season

274 days

Growing Tips for Humboldt County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Lemongrass in Humboldt County, CA?

Humboldt County is in Zone 9a with an average last frost of February 27. Plan your Lemongrass planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Humboldt County, CA?

Humboldt County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 27 and first fall frost is November 28.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Humboldt County gardeners in Zone 9a organize planting dates, track what's growing, and never miss a planting window.

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Free download. Plan your entire garden season in minutes.

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