When to Plant Shiso in Orange County, CA
Shiso (perilla) is a fragrant Japanese herb with large, ruffled leaves in green or purple varieties. It has a unique flavor combining mint, basil, and anise.
Orange County, California is in USDA Zone 10a. The average last spring frost is February 13 and the first fall frost is December 11, giving you a growing season of approximately 301 days.
At an elevation of 405 feet, Orange County receives approximately 13.8 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Shiso during the growing season. With low rainfall, drip irrigation is essential for growing Shiso successfully. Mulch heavily to conserve soil moisture.
Orange County Soil Profile
Soil Type
Loam
Soil pH
5.7-7.6
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 Orange County
How your county's soil matches Shiso's growing requirements.
Soil pH
Your soil pH (5.7–7.6) overlaps with Shiso's range (5.5–7.0), though not a perfect match.
Soil Texture
The loam soil in Orange County is excellent for Shiso — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.1%). Annual compost additions will help Shiso.
How to Plant Shiso
Succession Planting Shiso
Sow every 5.7 weeks. Last sowing by Oct 02 to harvest before frost.
Plant Water Budget
Water stress score is 10/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Shiso
Shiso needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Shiso Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.4" | 0" | ❄️ Dormant |
| Feb | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Mar | 4.3" | 2.2" | 2.1" | 💧 Light watering |
| Apr | 4.3" | 1.1" | 3.2" | 🚿 Regular watering |
| May | 4.3" | 0.4" | 3.9" | 🚿 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" | 0.7" | 3.6" | 🚿 Regular watering |
| Nov | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Dec | 4.3" | 2.7" | 1.6" | 💧 Light watering |
Water needs are for active growing months only (Feb–Dec in Orange County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Shiso 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.
Shiso Planting Timeline — Orange County, CA
Shiso Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 2 | Jan 2 – Jan 16 |
| Transplant Outdoors | February 20 | Feb 20 – Mar 6 |
| Direct Sow | February 20 | Feb 20 – Mar 13 |
| Harvest | April 17 | Apr 17 – Jun 12 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Transplant Outdoors Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · 2-3 times/week
📅 Days to Maturity
50–70 days
🧪 Soil pH
Needs 5.5–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 10a
📆 Growing Season
301 days in Orange County
Growing Tips for Shiso in Orange County
Direct sow Shiso outdoors after February 13 in Orange County when soil has warmed and frost danger has passed.
Orange County receives only 14" of rain annually. Shiso needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow after last frost or start indoors. Both green and red varieties are available. Pinch tips to encourage bushiness. Self-sows prolifically; deadhead to control.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Shiso in Other Locations
Frequently Asked Questions
When should I plant Shiso in Orange County, CA?
Orange County is in Zone 10a with an average last frost of February 13. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.
What planting zone is Orange County, CA?
Orange County, California is in USDA Hardiness Zone 10a. The average last spring frost is February 13 and first fall frost is December 11.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Orange County gardeners in Zone 10a organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.