When to Plant Lemongrass in Sonoma County, CA
May in the garden — Sonoma County, California
A quick May briefing for Sonoma County, California gardeners — what's urgent, what's next, and what can wait.
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Bring in the lemongrass
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
June prep starts now
- First harvests: lemongrass
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.
Sonoma 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 91 feet, Sonoma County receives approximately 31.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 90°F, providing good warmth for Lemongrass during the growing season. Sandy soil warms quickly in spring — great for early planting — but Lemongrass will need more frequent watering and organic matter to retain nutrients.
Sonoma County Soil Profile
Soil Type
Sandy Loam
Soil pH
5.9-7
Drainage
Well Drained
Plant Planting Risk Windows
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 Sonoma County
How your county's soil matches Lemongrass's growing requirements.
Soil pH
Your soil pH (5.9–7.0) is within Lemongrass's preferred range (5.5–7.5).
Soil Texture
Sandy soil in Sonoma County warms quickly in spring but drains fast. Lemongrass will need more frequent watering and regular compost additions to retain nutrients.
Drainage
Lemongrass is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Lemongrass.
How to Plant Lemongrass
Succession Planting Lemongrass
Sow every 8.6 weeks. Last sowing by Jul 29 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — 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 | — | 6.2" | 0" | ❄️ Dormant |
| Feb | 6.5" | 6.8" | 0" | ✅ Rainfall sufficient |
| Mar | 6.5" | 5.2" | 1.3" | 💧 Light watering |
| Apr | 6.5" | 2.3" | 4.2" | 🚿 Regular watering |
| May | 6.5" | 0.8" | 5.7" | 🚿 Regular watering |
| Jun | 6.5" | 0.1" | 6.4" | 🚿 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" | 1.3" | 5.2" | 🚿 Regular watering |
| Nov | 6.5" | 2.7" | 3.8" | 🚿 Regular watering |
| Dec | — | 5.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Sonoma 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 Planting Timeline — Sonoma 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
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | — |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
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 Sonoma County
Growing Tips for Lemongrass in Sonoma County
Direct sow Lemongrass outdoors after February 26 in Sonoma County when soil has warmed and frost danger has passed.
Sandy soil in Sonoma 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 →
Lemongrass in Other Locations
Frequently Asked Questions
When should I plant Lemongrass in Sonoma County, CA?
Sonoma 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 Sonoma County, CA?
Sonoma County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 26.
Your Sonoma County Garden Planner — Free
A 24-page printable planner built for Sonoma 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.