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When to Plant Shiso in Sherman 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.

Sherman County, Oregon is in USDA Zone 6a. The average last spring frost is April 14 and the first fall frost is October 17, giving you a growing season of approximately 186 days.

At an elevation of 862 feet, Sherman County receives approximately 15 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89ยฐF, 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.

Sherman County, OR (Zone 6a) Moderate season
186 days
Last Spring Frost April 14
186 growing days
First Fall Frost October 17

Sherman County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (61 days to spare)
Start indoors: Feb 17 Transplant: Apr 21 🍅 Harvest: Jun 16 – Aug 11
Recommended (50%) ✓ Fits season (60 days to spare)
Start indoors: Feb 24 Transplant: Apr 28 🍅 Harvest: Jun 23 – Aug 18
Safe Start (90%) ✓ Fits season (58 days to spare)
Start indoors: Mar 14 Transplant: May 16 🍅 Harvest: Jul 11 – Sep 5

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
1.0″/week
Rainfall provides
0.3″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 1,095 gal / 100 sq ft
Shiso needs ~1,005 GDD — county provides 3,115 GDD Excellent fit

Shiso Planting Timeline โ€” Sherman County, OR

Shiso Planting Calendar

Activity When Date Range
Start Indoors February 24 Feb 24 โ€“ Mar 10
Transplant Outdoors April 28 Apr 28 โ€“ May 12
Direct Sow April 21 Apr 21 โ€“ May 12
Harvest June 23 Jun 23 โ€“ Aug 18

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

50โ€“70 days

Soil pH

5.5 โ€“ 7

USDA Zone

Zone 6a

Growing Season

186 days

Growing Tips for Sherman 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

Level Up Your Garden

Frequently Asked Questions

When should I plant Shiso in Sherman County, OR?

Sherman County is in Zone 6a with an average last frost of April 14. Plan your Shiso planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Sherman County, OR?

Sherman County, Oregon is in USDA Hardiness Zone 6a. The average last spring frost is April 14 and first fall frost is October 17.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Sherman County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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