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When to Plant Shiso in Windham County, CT

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.

Windham County, Connecticut is in USDA Zone 6a. The average last spring frost is April 29 and the first fall frost is October 16, giving you a growing season of approximately 170 days.

At an elevation of 110 feet, Windham County receives approximately 41.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Shiso during the growing season.

Windham County, CT (Zone 6a) Moderate season
170 days
Last Spring Frost April 29
170 growing days
First Fall Frost October 16

Windham County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (45 days to spare)
Start indoors: Mar 4 Transplant: May 6 🍅 Harvest: Jul 1 – Aug 26
Recommended (50%) ✓ Fits season (44 days to spare)
Start indoors: Mar 11 Transplant: May 13 🍅 Harvest: Jul 8 – Sep 2
Safe Start (90%) ✓ Fits season (44 days to spare)
Start indoors: Mar 27 Transplant: May 29 🍅 Harvest: Jul 24 – Sep 18

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
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Shiso needs ~825 GDD — county provides 2,337 GDD Excellent fit

Shiso Planting Timeline โ€” Windham County, CT

Shiso Planting Calendar

Activity When Date Range
Start Indoors March 11 Mar 11 โ€“ Mar 25
Transplant Outdoors May 13 May 13 โ€“ May 27
Direct Sow May 6 May 6 โ€“ May 27
Harvest July 8 Jul 8 โ€“ Sep 2

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

Month-by-Month Timeline

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

170 days

Growing Tips for Windham 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 Windham County, CT?

Windham County is in Zone 6a with an average last frost of April 29. Plan your Shiso planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Windham County, CT?

Windham County, Connecticut is in USDA Hardiness Zone 6a. The average last spring frost is April 29 and first fall frost is October 16.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Windham 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 Windham County, CT. Local conditions may vary. Last updated: April 2026.