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When to Plant Valerian in Johnson County, IL

Valerian is a tall perennial herb with fragrant white or pink flower clusters, valued for its root which is used as a natural sleep aid. It attracts pollinators and earthworms.

Johnson County, Illinois is in USDA Zone 6b. The average last spring frost is April 7 and the first fall frost is October 21, giving you a growing season of approximately 197 days.

At an elevation of 1,006 feet, Johnson County receives approximately 39.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90ยฐF, providing good warmth for Valerian during the growing season.

Johnson County, IL (Zone 6b) Moderate season
197 days
Last Spring Frost April 7
197 growing days
First Fall Frost October 21

Johnson County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Apr 10 🍅 Harvest: Aug 14 – Oct 23
Recommended (50%) ✗ May not fit
Transplant: Apr 14 🍅 Harvest: Aug 18 – Oct 27
Safe Start (90%) ✗ May not fit
Transplant: Apr 28 🍅 Harvest: Sep 1 – Nov 10

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
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 323 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Valerian needs ~2,625 GDD — county provides 3,447 GDD Excellent fit

Valerian Planting Timeline โ€” Johnson County, IL

Valerian Planting Calendar

Activity When Date Range
Transplant Outdoors April 14 Apr 14 โ€“ Apr 28
Harvest August 18 Aug 18 โ€“ Oct 27

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

120โ€“180 days

Soil pH

5.5 โ€“ 7

USDA Zone

Zone 6b

Growing Season

197 days

Growing Tips for Johnson County

Start seeds indoors and transplant after last frost. Harvest roots in fall of the second year. Deadhead flowers unless you want self-seeding. Cats are attracted to valerian root.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Valerian in Johnson County, IL?

Johnson County is in Zone 6b with an average last frost of April 7. Plan your Valerian planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Johnson County, IL?

Johnson County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 7 and first fall frost is October 21.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Johnson County gardeners in Zone 6b 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 Johnson County, IL. Local conditions may vary. Last updated: April 2026.