When to Plant Lemongrass in San Mateo County, CA
May in the garden — San Mateo County, California
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.
-
Collect lemongrass at their peak
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
To set up a strong June, finish these tasks
- 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.
San Mateo County, 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 Lemongrass to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Lemongrass successfully. Mulch heavily to conserve soil moisture.
San Mateo County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.2
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 San Mateo County
How your county's soil matches Lemongrass's growing requirements.
Soil pH
Your soil pH (6.8–7.2) is within Lemongrass's preferred range (5.5–7.5).
Soil Texture
The loam soil in San Mateo County is excellent for Lemongrass — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Lemongrass is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.
Organic Matter
Organic matter is moderate (2.6%). Annual compost additions will help Lemongrass.
How to Plant Lemongrass
Succession Planting Lemongrass
Sow every 8.6 weeks. Last sowing by Aug 14 to harvest before frost.
Plant Water Budget
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 | 6.5" | 3.9" | 2.6" | 💧 Light watering |
| Feb | 6.5" | 3.4" | 3.1" | 💧 Light watering |
| Mar | 6.5" | 2.7" | 3.8" | 🚿 Regular watering |
| Apr | 6.5" | 1.2" | 5.3" | 🚿 Regular watering |
| May | 6.5" | 0.4" | 6.1" | 🚿 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" | 0.2" | 6.3" | 🚿 Regular watering |
| Oct | 6.5" | 0.7" | 5.8" | 🚿 Regular watering |
| Nov | 6.5" | 1.4" | 5.1" | 🚿 Regular watering |
| Dec | 6.5" | 2.9" | 3.6" | 🚿 Regular watering |
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.
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 — San Mateo County, CA
Lemongrass Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 7 | Dec 7 – Dec 21 |
| Transplant Outdoors | January 25 | Jan 25 – Feb 8 |
| Direct Sow | January 25 | Jan 25 – Feb 15 |
| Harvest | April 12 | Apr 12 – Jul 12 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors Direct Sow |
| February | Transplant Outdoors Direct Sow |
| March | — |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | — |
| September | — |
| October | — |
| November | — |
| December | Start Indoors |
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 10a
📆 Growing Season
328 days in San Mateo County
Growing Tips for Lemongrass in San Mateo County
Direct sow Lemongrass outdoors after January 18 in San Mateo County when soil has warmed and frost danger has passed.
Common pests for Lemongrass in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.
San Mateo County receives only 17" of rain annually. Lemongrass needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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 San Mateo County, CA?
San Mateo County is in Zone 10a with an average last frost of January 18. Plan your Lemongrass planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Mateo County, CA?
San Mateo County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 18 and first fall frost is December 12.
Your San Mateo County Garden Planner — Free
A 24-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.