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When to Plant Asparagus in DeKalb County, IL

Asparagus is a long-lived perennial vegetable that produces tender spears each spring for 15-20 years once established. It requires patience but rewards with reliable harvests.

DeKalb County, Illinois is in USDA Zone 5a. The average last spring frost is April 22 and the first fall frost is October 16, giving you a growing season of approximately 177 days.

At an elevation of 1,332 feet, DeKalb County receives approximately 34.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Asparagus during the growing season.

DeKalb County, IL (Zone 5a) Moderate season
177 days
Last Spring Frost April 22
177 growing days
First Fall Frost October 16

DeKalb County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: Apr 30
Recommended (50%) ✓ Fits season
Transplant: May 6
Safe Start (90%) ✓ Fits season
Transplant: May 23

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
0.8″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 919 gal / 100 sq ft
Drought risk

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

Asparagus needs ~13,916 GDD — county provides 2,699 GDD May not mature

Asparagus Planting Timeline โ€” DeKalb County, IL

Asparagus Planting Calendar

Activity When Date Range
Transplant Outdoors May 6 May 6 โ€“ May 20

Plant 1" deep ยท 30" apart ยท Rows 42" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

730โ€“1095 days

Soil pH

6.5 โ€“ 7.5

USDA Zone

Zone 5a

Growing Season

177 days

Growing Tips for DeKalb County

Plant crowns in deep trenches with compost. Do not harvest spears for the first two years to allow root establishment. Mulch heavily to suppress weeds and retain moisture.

Companion Planting

Good Companions

Avoid Planting Near

  • Garlic
  • Onion

Level Up Your Garden

Frequently Asked Questions

When should I plant Asparagus in DeKalb County, IL?

DeKalb County is in Zone 5a with an average last frost of April 22. Plan your Asparagus planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is DeKalb County, IL?

DeKalb County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 22 and first fall frost is October 16.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help DeKalb County gardeners in Zone 5a 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 DeKalb County, IL. Local conditions may vary. Last updated: April 2026.