When to plant Asparagus in Downs, IL
Downs's short 183-day growing season means one Asparagus planting between May 2 and May 16. No fall crop in Zone 6a.
When to Plant Asparagus in Downs, IL
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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.
Downs, Illinois is in USDA Zone 6a. The average last spring frost is April 18 and the first fall frost is October 18, giving you a growing season of approximately 183 days.
At an elevation of 1,024 feet, McLean County receives approximately 31.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Asparagus during the growing season.
Downs Soil Profile
Soil Type
Silt Loam
Soil pH
6-7
Drainage
Well Drained
Asparagus Planting Risk Windows
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.
Soil Compatibility in Downs
How your county's soil matches Asparagus's growing requirements.
Soil pH
Your soil pH (6.0–7.0) overlaps with Asparagus's range (6.5–7.5), though not a perfect match.
Soil Texture
The silt loam soil in McLean County is excellent for Asparagus — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.1%) — Asparagus will thrive.
How to Plant Asparagus
Asparagus Water Budget
Monthly Watering Guide for Asparagus
Asparagus needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.
| Month | Asparagus Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 3.5" | 2.9" | 0.6" | 💧 Light watering |
| May | 3.5" | 4" | 0" | ✅ Rainfall sufficient |
| Jun | 3.5" | 3.8" | 0" | ✅ Rainfall sufficient |
| Jul | 3.5" | 3.5" | 0" | ✅ Rainfall sufficient |
| Aug | 3.5" | 3.2" | 0.3" | 💧 Light watering |
| Sep | 3.5" | 2.7" | 0.8" | 💧 Light watering |
| Oct | 3.5" | 2.8" | 0.7" | 💧 Light watering |
| Nov | — | 2" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in McLean County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Asparagus Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Asparagus Planting Timeline — Downs, IL
Asparagus Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 2 | May 2 – May 16 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.8"/week · Only during dry spells
📅 Days to Maturity
730–1095 days
🧪 Soil pH
Needs 6.5–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 6a
📆 Growing Season
183 days in McLean County
Growing Tips for Asparagus in Downs
Direct sow Asparagus outdoors after April 18 in McLean County when soil has warmed and frost danger has passed.
Your 183.0-day growing season in McLean County is tight for Asparagus (730.0-1095.0 days to maturity). Start indoors and choose early-maturing varieties.
General growing tips
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
Check more plant combinations with our Companion Planting Checker →
Asparagus in Other Locations
When should I plant Asparagus in Downs, IL?
In Downs, IL, plant Asparagus after the last frost (around April 18) and before the first frost (around October 18). Best results when soil holds above 50°F.
What growing zone is Downs, IL for Asparagus?
Downs sits in USDA Zone 6a. Asparagus grows reliably in zones 3a through 10b, so it's a good fit here.
Can Asparagus grow in Downs's climate?
Yes — Asparagus grows well in Downs's temperate climate. Downs averages a 183-day frost-free season, with last frost around April 18 and first frost around October 18.
Your McLean County Garden Planner — Free
A 22-page printable planner built for McLean County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.