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When to Plant Hyssop in Windham County, CT

Hyssop is a semi-evergreen perennial herb with intense blue flower spikes that attract bees and butterflies. It has a minty, slightly bitter flavor used in liqueurs and teas.

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 Hyssop 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 (31 days to spare)
Transplant: Apr 29 🍅 Harvest: Jul 8 – Sep 9
Recommended (50%) ✓ Fits season (30 days to spare)
Transplant: May 6 🍅 Harvest: Jul 15 – Sep 16
Safe Start (90%) ✓ Fits season (30 days to spare)
Transplant: May 22 🍅 Harvest: Jul 31 – Oct 2

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
0.5″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Hyssop needs ~1,100 GDD — county provides 2,337 GDD Excellent fit

Hyssop Planting Timeline โ€” Windham County, CT

Hyssop Planting Calendar

Activity When Date Range
Transplant Outdoors May 6 May 6 โ€“ May 20
Harvest July 15 Jul 15 โ€“ Sep 16

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

70โ€“90 days

Soil pH

6 โ€“ 8

USDA Zone

Zone 6a

Growing Season

170 days

Growing Tips for Windham County

Start seeds indoors or direct sow in spring. Prune back in early spring to encourage bushy growth. Hyssop is drought-tolerant once established and thrives in poor soil.

Companion Planting

Good Companions

Avoid Planting Near

  • Radish

Level Up Your Garden

Frequently Asked Questions

When should I plant Hyssop in Windham County, CT?

Windham County is in Zone 6a with an average last frost of April 29. Plan your Hyssop 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.

๐ŸŒฑ

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.