When to plant Onion in Edgar County, IL
In Edgar County, plant Onion in spring between April 4 and April 25, once soil temps hold above 50°F. Edgar County's last frost averages April 18, so time plantings around the expected last-frost window for best survival. For a fall crop, sow between August 8 and August 22 — roughly 90–120 days before the first frost on October 17.
When to Plant Onion in Edgar County, IL
Edgar County, Illinois gardeners: here's your July plan
Your garden in Edgar County, Illinois is working on a schedule, even when you're not. Here's where you should be this July.
-
Pick onion
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
Coming up in August — start thinking about
- First harvests: onion
- Fall sowing: onion
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
Edgar County, Illinois is in USDA Zone 6a. The average last spring frost is April 18 and the first fall frost is October 17, giving you a growing season of approximately 182 days.
At an elevation of 1,272 feet, Edgar County receives approximately 41.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Onion to ensure they mature before fall.
Edgar County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-6.8
Drainage
Well Drained
Onion 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 Edgar County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (5.9–6.8) overlaps with Onion's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Edgar County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.3%) — Onion will thrive.
How to Plant Onion
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Onion Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Onion
Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Onion Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.8" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| May | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 5.5" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.9" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Sep | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Oct | 4.3" | 3.3" | 1" | 💧 Light watering |
| Nov | — | 2.9" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Edgar County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion 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.
Onion Planting Timeline — Edgar County, IL
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 14 | Mar 14 – Mar 28 |
| Transplant Outdoors | April 18 | Apr 18 – May 2 |
| Direct Sow | April 4 | Apr 4 – Apr 25 |
| Harvest | July 18 | Jul 18 – Sep 5 |
| Fall Sowing | August 8 | Aug 8 – Aug 22 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 6a
📆 Growing Season
182 days in Edgar County
Growing Tips for Onion in Edgar County
Direct sow Onion outdoors after April 18 in Edgar County when soil has warmed and frost danger has passed.
Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Edgar County, IL?
Edgar County is in Zone 6a with an average last frost of April 18. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Edgar County, IL?
Edgar County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 18 and first fall frost is October 17.
When should I plant Onion in Edgar County, IL?
In Edgar County, IL, plant Onion after the last frost (around April 18) and before the first frost (around October 17). Best results when soil holds above 50°F.
What growing zone is Edgar County, IL for Onion?
Edgar County sits in USDA Zone 6a. Onion grows reliably in zones 3a through 10b, so it's a good fit here.
Can Onion grow in Edgar County's climate?
Yes — Onion grows well in Edgar County's temperate climate. Edgar County averages a 182-day frost-free season, with last frost around April 18 and first frost around October 17.
Your Edgar County Garden Planner — Free
A 22-page printable planner built for Edgar 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.