When to plant Garlic in Stephenson County, IL
Plant Garlic in Stephenson County, when soil hits 50°F — usually mid-spring. Continue planting through late spring for the spring crop. A second sowing from September 1 to September 15 extends the harvest into fall.
When to Plant Garlic in Stephenson County, IL
June to-do list for Stephenson County, Illinois
Your garden in Stephenson County, Illinois is working on a schedule, even when you're not. Here's where you should be this June.
Garlic is a pungent allium planted in fall and harvested the following summer. Hardneck varieties produce edible flower stalks (scapes) and are more cold-hardy.
Stephenson County, Illinois is in USDA Zone 5a. The average last spring frost is April 23 and the first fall frost is October 13, giving you a growing season of approximately 173 days.
At an elevation of 1,345 feet, Stephenson County receives approximately 36.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Garlic during the growing season.
Stephenson County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.1
Drainage
Well Drained
Garlic 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 Stephenson County
How your county's soil matches Garlic's growing requirements.
Soil pH
Your soil pH (6.2–7.1) is within Garlic's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Stephenson County is excellent for Garlic — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.5%) — Garlic will thrive.
How to Plant Garlic
Fall planting: Sow 6 weeks before your first frost date for a fall harvest.
Garlic Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Garlic
Garlic needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Garlic Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Stephenson County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Garlic 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.
Garlic Planting Timeline — Stephenson County, IL
Garlic Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Harvest | December 1 | Dec 1 – Feb 16 |
| Fall Sowing | September 1 | Sep 1 – Sep 15 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Harvest |
| February | Harvest |
| March | — |
| April | — |
| May | — |
| June | — |
| July | — |
| August | — |
| September | Fall Sowing |
| October | — |
| November | — |
| December | Harvest |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
90–240 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5a
📆 Growing Season
173 days in Stephenson County
Growing Tips for Garlic in Stephenson County
Direct sow Garlic outdoors after April 23 in Stephenson County when soil has warmed and frost danger has passed.
Your 173.0-day growing season in Stephenson County is tight for Garlic (90.0-240.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Garlic in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
Plant individual cloves pointed end up in fall, 6 weeks before ground freezes. Mulch heavily with straw. Harvest when lower leaves begin to brown but 5-6 green leaves remain.
Companion Planting
Good Companions
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Garlic in Other Locations
Frequently Asked Questions
When should I plant Garlic in Stephenson County, IL?
Stephenson County is in Zone 5a with an average last frost of April 23. Plan your Garlic planting based on this frost date — see the calendar above for exact timing.
What planting zone is Stephenson County, IL?
Stephenson County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 23 and first fall frost is October 13.
When should I plant Garlic in Stephenson County, IL?
In Stephenson County, IL, plant Garlic after the last frost (around April 23) and before the first frost (around October 13). Best results when soil holds above 50°F.
What growing zone is Stephenson County, IL for Garlic?
Stephenson County sits in USDA Zone 5a. Garlic grows reliably in zones 3a through 9b, so it's a good fit here.
Can Garlic grow in Stephenson County's climate?
Yes — Garlic grows well in Stephenson County's temperate climate. Stephenson County averages a 173-day frost-free season, with last frost around April 23 and first frost around October 13.
Your Stephenson County Garden Planner — Free
A 22-page printable planner built for Stephenson County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.