When to Plant Shiso in Washington County, OR
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.
Washington County, Oregon is in USDA Zone 8b. The average last spring frost is April 15 and the first fall frost is October 27, giving you a growing season of approximately 195 days.
At an elevation of 352 feet, Washington County receives approximately 47.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Shiso during the growing season.
Washington County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-6.4
Drainage
Well Drained
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 | — | 7.4" | 0" | ❄️ Dormant |
| Feb | — | 5.7" | 0" | ❄️ Dormant |
| Mar | — | 4.2" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3" | 1.3" | 💧 Light watering |
| May | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Jun | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Jul | 4.3" | 0.6" | 3.7" | 🚿 Regular watering |
| Aug | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Sep | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Oct | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| Nov | — | 7.3" | 0" | ❄️ Dormant |
| Dec | — | 8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Washington County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Shiso Planting Timeline — Washington County, OR
Shiso Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 25 | Feb 25 – Mar 11 |
| Transplant Outdoors | April 29 | Apr 29 – May 13 |
| Direct Sow | April 22 | Apr 22 – May 13 |
| Harvest | June 24 | Jun 24 – Aug 19 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
50–70 days
🧪 Soil pH
Needs 5.5–7 · Your soil: N/A
🗺️ USDA Zone
Zone 8b
📆 Growing Season
195 days in Washington County
Growing Tips for Washington County
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 Washington County, OR?
Washington County is in Zone 8b with an average last frost of April 15. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.
What planting zone is Washington County, OR?
Washington County, Oregon is in USDA Hardiness Zone 8b. The average last spring frost is April 15 and first fall frost is October 27.
Your Washington County Garden Planner — Free
A 22-page printable planner built for Washington County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.